HomeMy WebLinkAbout2024 General Sewer PlanAGENCY DRAFT: FEBRUARY 2024
City of Port Townsend
GENERAL SEWER PLAN
PREPARED BY RH2 ENGINEERING
Dan Mahlum, PE, Project Manager
AGENCY REVIEW DRAFT MAY 2024MAY 2024
FINAL JULY 2024
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City of Port Townsend
General Sewer Plan
MAY 2024
FINAL JULY 2024
Mayor
David Faber
Deputy Mayor
Amy Howard
City Council
Aislinn Palmer
Ben Thomas
Libby Urner Wennstrom
Monica MickHager
Owen Rowe
Public Works Director
Steve King, PE
Wastewater Operations Manager
Bliss Morris
Streets and Collections Manager
Brian Reid
City of Port Townsend
250 Madison Street
Port Townsend, WA 98368
Prepared By
RH2 Engineering, Inc.
22722 29th Drive SE, Suite 210
Bothell, WA 98021
Contact: Dan Mahlum, PE
(425) 951-5340
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CERTIFICATION
This General Sewer Plan for the City of Port Townsend was prepared under the direction
of the following registered professional engineers.
_____________________________________
Eric Smith, PE
Chapter 8
_____________________________________
John Hendron, PE
Collections System
_____________________________________
Dan Mahlum, PE
Principal
05/07/2024
05/07/2024
05/07/2024
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City of Port Townsend General Sewer Plan
Table of Contents
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E | Executive Summary ....................................................................................................... E-1
PURPOSE OF THE PLAN .......................................................................................................................... E-1
SUMMARY OF KEY ELEMENTS ............................................................................................................... E-1
Sewer Service Area, Land Use, and Population ................................................................................. E-1
Existing Facilities and Discharge Regulations .................................................................................... E-2
Existing Wastewater Flow and Loading ............................................................................................. E-6
Inflow and Infiltration........................................................................................................................ E-8
Peaking Factors ................................................................................................................................. E-8
Projected Wastewater Flow .............................................................................................................. E-9
Projected Wastewater Quality ........................................................................................................ E-10
Policies and Design Criteria ............................................................................................................. E-12
Operation and Maintenance ........................................................................................................... E-13
Summary of Improvements ............................................................................................................. E-13
1 | Introduction .................................................................................................................. 1-1
SEWER SYSTEM OWNERSHIP AND MANAGEMENT ............................................................................... 1-1
OVERVIEW OF EXISTING SYSTEM .......................................................................................................... 1-1
AUTHORIZATION AND PURPOSE ........................................................................................................... 1-2
PREVIOUS PLANNING EFFORTS ............................................................................................................. 1-3
SUMMARY OF PLAN CONTENTS ............................................................................................................ 1-3
LIST OF ABBREVIATIONS ........................................................................................................................ 1-3
2 | Sewer System Description and Discharge Regulations ................................................... 2-1
INTRODUCTION ..................................................................................................................................... 2-1
SEWER SERVICE AREA ............................................................................................................................ 2-1
History ............................................................................................................................................... 2-1
Geology.............................................................................................................................................. 2-2
Topography ....................................................................................................................................... 2-2
Climate .............................................................................................................................................. 2-3
Water Bodies and Floodplains........................................................................................................... 2-3
City Limits, Urban Growth Area, and Sewer Service Area Boundary ................................................ 2-4
EXISTING SEWER FACILITIES .................................................................................................................. 2-5
Sewer Drainage Basins ...................................................................................................................... 2-5
Gravity Sewer Collection Piping ........................................................................................................ 2-6
Force Mains ....................................................................................................................................... 2-8
Lift Stations ........................................................................................................................................ 2-9
Low Pressure Sewer Systems .......................................................................................................... 2-12
Wastewater Treatment and Disposal Facilities ............................................................................... 2-14
DISCHARGE AND DISPOSAL REGULATIONS AND PERMITS .................................................................. 2-15
WWTF NPDES Permit and Regulations ............................................................................................ 2-15
Future City NPDES Permit Effluent Limits (Outfall No. 001) Changes ............................................. 2-16
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Other Regulations and Required Permits ........................................................................................ 2-17
ADJACENT SEWER SYSTEMS ................................................................................................................ 2-23
CITY OF PORT TOWNSEND AND ADJACENT WATER SYSTEMS ............................................................ 2-23
City of Port Townsend ..................................................................................................................... 2-23
Adjacent Water Systems ................................................................................................................. 2-26
3 | Land Use and Population ............................................................................................... 3-1
INTRODUCTION ..................................................................................................................................... 3-1
COMPATIBILITY WITH OTHER PLANS AND POLICIES ............................................................................. 3-1
Growth Management Act .................................................................................................................. 3-1
Port Townsend Comprehensive Plan ................................................................................................ 3-2
Jefferson County County-wide Planning Policies .............................................................................. 3-2
Jefferson County Comprehensive Plan ............................................................................................. 3-3
LAND USE ............................................................................................................................................... 3-3
POPULATION .......................................................................................................................................... 3-5
Household Trends ............................................................................................................................. 3-5
Historical and Future City Population ............................................................................................... 3-5
Sewer System Population .................................................................................................................. 3-7
Distribution of Population Assumptions ........................................................................................... 3-8
4 | Flow and Loading Analyses ............................................................................................ 4-1
INTRODUCTION ..................................................................................................................................... 4-1
SEWER SERVICE CONNECTIONS AND RESIDENTIAL POPULATION ........................................................ 4-1
Sewer Service Connections ............................................................................................................... 4-1
Sewer Service Population .................................................................................................................. 4-2
EXISTING WASTEWATER FLOW AND LOADING ..................................................................................... 4-3
Wastewater Flow .............................................................................................................................. 4-3
Wastewater Loading ......................................................................................................................... 4-4
INFLOW AND INFILTRATION .................................................................................................................. 4-6
Inflow ................................................................................................................................................. 4-6
Infiltration .......................................................................................................................................... 4-7
PROJECTED WASTEWATER FLOW AND LOADING ................................................................................. 4-7
Peaking Factors ................................................................................................................................. 4-8
Projected Wastewater Flow Rates .................................................................................................... 4-9
Historical Wastewater Flow by Basin .............................................................................................. 4-12
Projected Wastewater Flow by Basin .............................................................................................. 4-13
Lift Station Hydraulic Capacity Analyses ......................................................................................... 4-14
Projected Wastewater Loading Capacity ........................................................................................ 4-15
SUMMARY ........................................................................................................................................... 4-22
5 | Policies and Collection System Design Criteria ............................................................... 5-1
INTRODUCTION ..................................................................................................................................... 5-1
City of Port Townsend General Sewer Plan
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REGULATIONS ........................................................................................................................................ 5-2
National Pollutant Discharge Elimination System Permit ................................................................. 5-2
Other Regulations and Required Permits .......................................................................................... 5-2
CUSTOMER SERVICE POLICIES ............................................................................................................... 5-2
Existing Sewer Service and Connection ............................................................................................. 5-2
Proposed Sewer Service and Connection Policies ............................................................................. 5-3
Septic System Policies ....................................................................................................................... 5-4
COLLECTION SYSTEM POLICIES AND DESIGN CRITERIA ......................................................................... 5-5
Sanitary Sewer Design Criteria .......................................................................................................... 5-5
Gravity Sewer Design Criteria ............................................................................................................ 5-5
Design Flow Rates ............................................................................................................................. 5-6
Separation Between Sanitary Sewer and Other Utilities .................................................................. 5-6
Design Period..................................................................................................................................... 5-6
Force Main Design Criteria ................................................................................................................ 5-7
Low Pressure Sewer Design Criteria .................................................................................................. 5-7
Side Sewer Design Criteria ................................................................................................................ 5-7
LIFT STATION POLICIES AND DESIGN CRITERIA ..................................................................................... 5-7
OPERATIONAL POLICIES ......................................................................................................................... 5-8
Facilities Maintenance ....................................................................................................................... 5-8
Collection System Maintenance ........................................................................................................ 5-8
Temporary and Emergency Services ................................................................................................. 5-9
Reliabilities ........................................................................................................................................ 5-9
ORGANIZATIONAL POLICIES .................................................................................................................. 5-9
Staffing .............................................................................................................................................. 5-9
FINANCIAL POLICIES............................................................................................................................. 5-10
General ............................................................................................................................................ 5-10
Connection Charges ........................................................................................................................ 5-12
6 | Sewer Collection System Evaluation .............................................................................. 6-1
INTRODUCTION ..................................................................................................................................... 6-1
COLLECTION SYSTEM ANALYSIS ............................................................................................................. 6-1
Hydraulic Model ................................................................................................................................ 6-1
Hydraulic Analyses Results ................................................................................................................ 6-2
Other Existing Gravity Collection System Deficiencies ...................................................................... 6-8
LIFT STATION ANALYSIS ....................................................................................................................... 6-10
Lift Station Capacity ......................................................................................................................... 6-10
7 | Existing Treatment Facilities Assessment ....................................................................... 7-1
BACKGROUND........................................................................................................................................ 7-1
History and Introduction ................................................................................................................... 7-1
System Overview ............................................................................................................................... 7-1
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Historical WWTF Performance .......................................................................................................... 7-2
WWTF EXISTING PROCESS UNITS EVALUATION .................................................................................... 7-4
Introduction ....................................................................................................................................... 7-4
Influent Pump Station ....................................................................................................................... 7-4
Headworks ......................................................................................................................................... 7-5
Activated Sludge System ................................................................................................................... 7-7
Sludge Holding, Dewatering, and Disposal ...................................................................................... 7-10
Odor Control System ....................................................................................................................... 7-11
Electrical and SCADA Existing Systems Evaluation .......................................................................... 7-12
COMPOST FACILITY EXISTING SYSTEMS EVALUATION ........................................................................ 7-15
Overview ......................................................................................................................................... 7-15
Condition Assessment ..................................................................................................................... 7-17
Summary of Major Findings ............................................................................................................ 7-18
TREATMENT FACILITIES ASSESSMENT CONCLUSION .......................................................................... 7-18
8 | Treatment Facilities Analysis ......................................................................................... 8-1
INTRODUCTION ..................................................................................................................................... 8-1
MAJOR CONSIDERATIONS FOR WWTF IMPROVEMENTS ...................................................................... 8-1
Growth in Flow and Loading ............................................................................................................. 8-1
Regulatory Changes – Nitrogen Reduction ....................................................................................... 8-2
WWTF Site Footprint ......................................................................................................................... 8-3
Age and Condition ............................................................................................................................. 8-5
APPROACH TO WWTF ANALYSES .......................................................................................................... 8-5
ACTIVATED SLUDGE SYSTEM ................................................................................................................. 8-6
Existing Activated Sludge System ...................................................................................................... 8-6
Screening of Nitrogen Treatment Options ...................................................................................... 8-10
Improvements to the Existing Oxidation Ditch System ................................................................... 8-14
Replacement of the Existing Oxidation Ditch System ..................................................................... 8-17
Activated Sludge System Recommendations .................................................................................. 8-20
PRELIMINARY TREATMENT .................................................................................................................. 8-22
Summary of Analysis ....................................................................................................................... 8-22
Recommendations .......................................................................................................................... 8-23
EFFLUENT DISINFECTION ..................................................................................................................... 8-24
Summary of Analysis ....................................................................................................................... 8-24
Recommendations .......................................................................................................................... 8-25
OUTFALL .............................................................................................................................................. 8-25
TERTIARY TREATMENT – WATER REUSE/RECLAMATION .................................................................... 8-26
SOLIDS HANDLING ............................................................................................................................... 8-28
On-Site WWTF Solids Handling System ........................................................................................... 8-28
Off-Site Compost Facility ................................................................................................................. 8-30
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ELECTRICAL AND CONTROLS ............................................................................................................... 8-31
REFERENCES ......................................................................................................................................... 8-33
9 | Operations and Maintenance ........................................................................................ 9-1
INTRODUCTION ..................................................................................................................................... 9-1
NORMAL OPERATIONS .......................................................................................................................... 9-1
City Personnel .................................................................................................................................... 9-1
Personnel Responsibilities ................................................................................................................. 9-2
Certification of Personnel .................................................................................................................. 9-3
Available Equipment ......................................................................................................................... 9-4
Routine Operations ........................................................................................................................... 9-4
Continuity of Service ......................................................................................................................... 9-5
Routine Wastewater Quality Sampling ............................................................................................. 9-5
EMERGENCY OPERATIONS..................................................................................................................... 9-5
Capabilities ........................................................................................................................................ 9-5
PREVENTIVE MAINTENANCE ................................................................................................................. 9-7
Wastewater Division ......................................................................................................................... 9-7
STAFFING ............................................................................................................................................... 9-9
Current Staff ...................................................................................................................................... 9-9
Proposed Staffing .............................................................................................................................. 9-9
10 | Capital Improvement Plan ........................................................................................... 10-1
INTRODUCTION ................................................................................................................................... 10-1
DESCRIPTION OF IMPROVEMENTS ...................................................................................................... 10-2
5-Year System Improvements ......................................................................................................... 10-2
6- to 10-Year System Improvements .............................................................................................. 10-9
11- to 20-Year System Improvements (Long-Term Planning Capital Improvements) .................. 10-10
Planning Improvements ................................................................................................................ 10-13
ESTIMATING COSTS OF IMPROVEMENTS .......................................................................................... 10-13
PRIORITIZING IMPROVEMENTS ......................................................................................................... 10-15
SCHEDULE OF IMPROVEMENTS ......................................................................................................... 10-15
Future Project Cost Adjustments .................................................................................................. 10-15
11 | Financial Analysis ........................................................................................................ 11-1
INTRODUCTION ................................................................................................................................... 11-1
FINANCIAL HISTORY ............................................................................................................................. 11-1
CAPITAL FUNDING RESOURCES ........................................................................................................... 11-3
Grant and Low-Cost Loan Programs ................................................................................................ 11-3
System Development Charges (SDCs) ............................................................................................. 11-3
Bonds ............................................................................................................................................... 11-5
CURRENT REVENUE ............................................................................................................................. 11-5
Financial Policies.............................................................................................................................. 11-6
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Revenue Requirement ................................................................................................................... 11-12
CURRENT AND PROJECTED SEWER RATES......................................................................................... 11-13
Utility Rate Affordability Analysis .................................................................................................. 11-14
CONCLUSION ..................................................................................................................................... 11-20
TABLES
Table ES-1 Land Use Inside Future Wastewater Service Area .................................................................. E-2
Table ES-2 2021 City Sewer System Data .................................................................................................. E-3
Table ES-3 Gravity Sewer Collection Piping Inventory – Diameter ........................................................... E-3
Table ES-4 Force Main Inventory – Diameter ........................................................................................... E-4
Table ES-5 Lift Station Characteristics ....................................................................................................... E-4
Table ES-6 WWTF Permitted Flow and Loading Design Criteria ............................................................... E-5
Table ES-7 SWDP SBR Effluent Limits ........................................................................................................ E-6
Table ES-8 SWDP Wetland Effluent Limits ................................................................................................ E-6
Table ES-9 Historical WWTF Influent Flow Summary ............................................................................... E-7
Table ES-10 Historical WWTF Influent BOD5 Loading Summary ............................................................... E-7
Table ES-11 Historical WWTF Influent TSS Loading Summary .................................................................. E-7
Table ES-12 WWTF Peaking Factor Summary for Flows ........................................................................... E-9
Table ES-13 WWTF Peaking Factor Summary for Loadings ...................................................................... E-9
Table ES-14 Total Projected WWTF Flow including Special Study Area Expansion ................................ E-10
Table ES-15 Total Projected WWTF BOD5 Loading including Special Study Area Expansion .................. E-11
Table ES-16 Total Projected WWTF Influent TSS Loading including Special Study Area Expansion ....... E-12
Table ES-17 Proposed CIP Implementation Schedule ............................................................................. E-15
Table 1-1 2021 City Sewer System Data ................................................................................................... 1-2
Table 1-2 Abbreviations ............................................................................................................................ 1-4
Table 2-1 Gravity Sewer Collection Piping Inventory – Diameter ............................................................. 2-7
Table 2-2 Gravity Sewer Collection Piping Inventory – Material .............................................................. 2-7
Table 2-3 Gravity Sewer Collection Piping Inventory – Installation Year .................................................. 2-8
Table 2-4 Force Main Inventory – Diameter ............................................................................................. 2-8
Table 2-5 Force Main Inventory – Material .............................................................................................. 2-9
Table 2-6 Force Main Inventory – Installation Year .................................................................................. 2-9
Table 2-7 Lift Station Characteristics ...................................................................................................... 2-10
Table 2-8 WWTF Permitted Flow and Loading Design Criteria ............................................................... 2-16
Table 2-9 NPDES Permit Effluent Limits .................................................................................................. 2-16
Table 2-10 Comparison of City NPDES Permit and PSNGP Monitoring Requirements for WWTF
Influent ................................................................................................................................. 2-20
Table 2-11 Comparison of City NPDES Permit and PSNGP Monitoring Requirements for WWTF
Effluent ................................................................................................................................. 2-20
Table 2-12 Compost Facility Flow and Loading Design Criteria .............................................................. 2-22
Table 2-13 State Waste Discharge Permit SBR Effluent Limits ............................................................... 2-22
Table 2-14 State Waste Discharge Permit Wetland Effluent Limits ....................................................... 2-22
Table 2-15 Booster Pump Station Facilities Summary ............................................................................ 2-25
Table 2-16 Storage Facilities Summary ................................................................................................... 2-25
Table 3-1 Land Use Inside Future Wastewater Service Area .................................................................... 3-4
Table 3-2 Population Trends within the City Limits .................................................................................. 3-5
Table 3-3 Population Projections .............................................................................................................. 3-6
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Table 4-1 Historical Sewer Connections Summary ................................................................................... 4-2
Table 4-2 Historical Sewer Service Population ......................................................................................... 4-3
Table 4-3 Historical WWTF Influent Flow Summary ................................................................................. 4-4
Table 4-4 Historical WWTF Influent BOD5 Loading Summary ................................................................... 4-5
Table 4-5 Historical WWTF Influent TSS Loading Summary ...................................................................... 4-5
Table 4-6 Peaking Factor Summary for Flows ........................................................................................... 4-8
Table 4-7 Peaking Factor Summary for Loadings ...................................................................................... 4-9
Table 4-8 Projected WWTF Influent Flow for Sewer System Population Within City Limits .................. 4-10
Table 4-9 Projected WWTF Influent Flow for Sewer System Special Study Area Expansion .................. 4-11
Table 4-10 Total Projected WWTF Flow including Special Study Area Expansion .................................. 4-12
Table 4-11 Historical AAF and PHF Rates by Lift Station ......................................................................... 4-13
Table 4-12 Existing and Projected AAF and PHF Rates by Basin ............................................................. 4-14
Table 4-13 Current AAF and PHF Rates and Remaining Capacity by Lift Station .................................... 4-14
Table 4-14 Projected WWTF Influent BOD5 Loading for Sewer System Population Within City Limits .. 4-16
Table 4-15 Projected WWTF Influent BOD5 Loading for Sewer System Special Study Area Expansion . 4-17
Table 4-16 Total Projected WWTF BOD5 Loading including Special Study Area Expansion ................... 4-18
Table 4-17 Projected WWTF Influent TSS Loading for Sewer System Population Within City Limits..... 4-19
Table 4-18 Projected WWTF Influent TSS Loading for Sewer System Special Study Area Expansion .... 4-20
Table 4-19 Total Projected WWTF TSS Loading including Special Study Area Expansion ...................... 4-21
Table 4-20 Summary of Existing and Projected Flow and Loading at the WWTF ................................... 4-22
Table 7-1 WWTF Performance Based on NPDES Permit Effluent Limits (2019-2022) .............................. 7-3
Table 7-2 Monthly Nitrogen Sampling Results ......................................................................................... 7-3
Table 8-1 Projected Influent Flow and Loading ........................................................................................ 8-2
Table 8-2 Original Oxidation Ditch Design Criteria ................................................................................... 8-6
Table 8-3 Original Facility Design Flow and Load ...................................................................................... 8-7
Table 8-4 Predicted Clarifier SLR for Existing Activated Sludge System at MLSS 2,800 mg/L .................. 8-8
Table 8-5 Preliminary Treatment Design Criteria from 1990 Project ..................................................... 8-23
Table 8-6 Disinfection System Design Criteria from 1990 Project .......................................................... 8-24
Table 8-7 Aerobic Holding Tank Design Criteria from 1990 Project ....................................................... 8-29
Table 8-8 Dewatering System Design Criteria from 1990 Project .......................................................... 8-29
Table 9-1 Personnel Certification .............................................................................................................. 9-3
Table 9-2 Wastewater Division Equipment List ........................................................................................ 9-4
Table 9-3 Utility and Agency Contacts ...................................................................................................... 9-6
Table 10-1 Gravity Sewer Pipe Unit Costs for Open-Cut Construction ................................................. 10-14
Table 10-2 Gravity Sewer Pipe Unit Costs for Cured-in-Place Pipe....................................................... 10-14
Table 10-3 Proposed CIP Implentation Schedule .................................................................................. 10-17
Table 11-1 Summary of Historical Financial Performance ($000s) ......................................................... 11-2
Table 11-2 Sewer SDC Calculation .......................................................................................................... 11-4
Table 11-3 Capital Cost Forecast ............................................................................................................. 11-9
Table 11-4 Capital Funding Strategy ..................................................................................................... 11-11
Table 11-5 Projected Financial Performance and Revenue Requirements ($000s) ............................. 11-13
Table 11-6 Sewer Rate Forecast ............................................................................................................ 11-14
Table 11-7 Combined Utility Bill Forecast ............................................................................................. 11-15
Table 11-8 Monthly Utility Bill as a Percentage of Median Household Income ................................... 11-16
Table 11-9 Rate Affordability Assessment Based on HM and AR20 ....................................................... 11-18
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Table 11-10 Summary of Rate Burden Evaluation Based on EPA Methodology .................................. 11-19
Table 11-11 Rate Burden Assessment Based on EPA Methodology ..................................................... 11-20
CHARTS
Chart 3-1 Population Projections .............................................................................................................. 3-7
Chart 4-1 2021 Sewer Service Connections by Customer Class ................................................................ 4-2
FIGURES
Figure 2-1 Existing Sewer System
Figure 2-2 Sewer Drainage Basins
Figure 2-3 Sewer Drainage Basins Schematic
Figure 2-4 Pipe Material
Figure 2-5A Known Pipe Age
Figure 2-5B Assumed Pipe Age
Figure 2-6 Wastewater Treatment Facilities in Vicinity
Figure 2-7 Existing Sewer and Water System
Figure 2-8 Topography Map
Figure 3-1 Existing Land Use Map
Figure 3-2 Possible Service Area Expansion
Figure 3-3 Allocation of Future Population by Planning Area
Figure 6-1 CIP SM1
Figure 6-2 CIP SM2
Figure 6-3 CIPs SM3 and SM4
Figure 6-4 CIP SM5
Figure 6-5 CIP SM6
Figure 6-6 CIP SM7
Figure 6-7 CIP SM10
Figure 6-8 Washington Sewer Street with Cracks
Figure 6-9 CIP SM9
Figure 7-1 Existing WWTF Overall Site Plan
Figure 7-2 Existing WWTF Process Schematic
Figure 7-3 Existing Compost Facility Overall Site Plan
Figure 7-4 Existing Compost Facility Process Schematic
Figure 8-1 WWTF and Surrounding Parcels
Figure 8-2 WWTF Site Aerial
Figure 8-3 Existing Oxidation Ditch Configuration
Figure 8-4 Current Operation of Existing Oxidation Ditch with Aerator at Low Speed
Figure 8-5 Conceptual Conversion of Existing Oxidation Ditches to MLE Configuration
Figure 8-6 Conceptual Conversion of Existing Oxidation Ditches to Cyclic Operation
Figure 8-7 Sea Level Rise Projects for 17% Probability of Exceedance including Storm Surge
Figure 8-8 WWTF and Surrounding Parcels
Figure 8-9 Adjacent Parcel Acquisition Considerations
Figure 8-10 Basic Configuration of Expanded WWTF
Figure 8-11 Approximate Outfall Configuration
Figure 9-1 Wastewater Division Organization Chart
Figure 10-1 Capital Improvement Plan Map Collection System
City of Port Townsend General Sewer Plan
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APPENDICES
Appendix A – 2019 Stormwater Management Plan
Appendix B – 2012 Mill Road Pump Station and Force Main Predesign Report by CH2M HILL
Appendix C – NPDES Permit
Appendix D – PSNGP
Appendix E – State Waste Discharge Permit
Appendix F – SEPA Checklist/DNS and SERP/Affirmed Determination
Appendix G – City Wastewater Engineering Standards
Appendix H – 2016 to 2021 WWTF Influent Flow and Loading Summaries
Appendix I – Hydraulic Model Data
Appendix J – Mill Site Lift Station Sizing Analysis
Appendix K – 2022 City of Port Townsend Sea Level Rise and Coastal Flooding Risk Assessment
Appendix L – 2019 Port Townsend Condition Assessment Summary Report by Jacobs
Appendix M – City Resolutions and Ordinances
Appendix N – Funding Program Summary
Appendix O – Port Townsend Sewer Rate Model
Appendix P – Agency Review Correspondence
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E | EXECUTIVE SUMMARY
PURPOSE OF THE PLAN
The City of Port Townsend’s (City) sewer system is a major infrastructure, most of which is
invisible to the customers it serves. The sewer system requires qualified staff to operate and
maintain an ongoing capital improvement plan to replace old components to meet the
requirements mandated by federal and state laws. The primary purpose of the City’s General
Sewer Plan (GSP) is to identify and schedule sewer system improvements that correct existing
deficiencies and ensure a safe and reliable sewer system for current and future customers. This
GSP has been prepared in accordance with Washington Administrative Code (WAC)
173-240-050.
SUMMARY OF KEY ELEMENTS
Sewer Service Area, Land Use, and Population
The City limits coincide with the Urban Growth Area (UGA) boundary, and encompass an area
of approximately 7.4 square miles. Approximately 50 percent of the land within the City’s
future wastewater service area is designated for residential use, while the remaining land is
designated for other uses such as open space/parks, commercial use, public/infrastructure use,
and other land uses. Table ES-1 presents the land uses within the future wastewater service
area. Chapter 3 provides more information regarding the population projections and
designated land use within the City’s planning area.
The City’s 2021 population was 10,220 people, which is expected to grow to 13,300 people by
2043. The City’s residential areas largely are comprised of single-family homes, with
approximately 75 percent of the housing units being single-family residences. The 2021 sewer
service population is estimated at approximately 9,829 people. The City’s sewer system
population is expected to grow to 12,720 people in 2033 and to 15,242 people by 2043. The
residential population estimate is based on an average single-family household size of
1.9 persons per household in the City.
EXECUTIVE SUMMARY CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table ES-1
Land Use Inside Future Wastewater Service Area
Existing Facilities and Discharge Regulations
The City’s sewer system includes a gravity collection and conveyance system, seven wastewater
lift stations, force mains, the wastewater treatment facility (WWTF), a Compost Facility, and an
outfall. A summary of the sewer system characteristics is provided in Table ES-2. Chapter 2
describes the City’s gravity collection and conveyance system, lift station, and general WWTF
characteristics.
Land Use Type Acres % of Total
Commercial 205 4.6%
Mixed Use 101 2.3%
Marine-Related Use 86 1.9%
Public/Infrastructure 150 3.4%
Park/Open Space 588 13.2%
Residential 2,254 50.5%
Undesignated 1,081 24.2%
Total 4,466 100.0%
Commercial
4.6%
Mixed Use
2.3%Marine-Related Use
1.9%
Public/Infrastructure
3.4%
Park/Open Space
13.2%
Residential
50.5%
Undesignated
24.2%
CITY OF PORT TOWNSEND GENERAL SEWER PLAN EXECUTIVE SUMMARY
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Table ES-2
2021 City Sewer System Data
Gravity Sewer Collection Piping
The City’s existing sewer service area is comprised of 14 sewer drainage basins. Approximately
75.2 miles of gravity sewer piping, ranging in size from 6 to 30 inches, serves the City’s sewer
system customers. As shown in Table ES-3, most of the sewer pipe (approximately 60 percent)
within the sewer service area is 8-inch diameter.
Table ES-3
Gravity Sewer Collection Piping Inventory – Diameter
EXECUTIVE SUMMARY CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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The City also has 2.2 miles of force mains. A summary of the force mains by diameter is
provided in Table ES-4.
Table ES-4
Force Main Inventory – Diameter
Lift Stations
The City currently owns, operates, and maintains seven wastewater lift stations. The
characteristics of the lift stations are summarized in Table ES-5.
Table ES-5
Lift Station Characteristics
Wastewater Treatment and Disposal Facilities
The City’s WWTF is located just west of Fort Worden in the North Beach neighborhood. The
WWTF originally was constructed in 1967 and provided primary treatment and disinfection
using chlorine gas. The WWTF was expanded in 1993 to provide secondary treatment.
Raw wastewater enters the WWTF from two gravity sewers, and an inf luent pump station lifts
the wastewater to the headworks. Within the headworks, a bar screen removes rags and
floating debris, and then a grit classifier settles out the sand and heavy materials. The flow rate
of the screened and de-gritted influent is measured in a Parshall flume and the liquid then flows
Diameter
(inches)
Total Length
(feet)
Total Length
(Miles)% of System
Year Constructed
Force Main
Diameter
(inches)
No. of
Pumps Type Manufacturer
Horsepower
(hp)
TDH
(feet)
Design
Capacity
(gpm)
Design
Firm
Capacity
(gpm)
CITY OF PORT TOWNSEND GENERAL SEWER PLAN EXECUTIVE SUMMARY
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to the oxidation ditches. In the oxidation ditches, surface mixers stir air into the liquid,
promoting the growth of microbiological cultures that consume the biochemical oxygen
demand in the mixture and form a solution known as mixed liquor. The mixed liquor flows to
the secondary clarifier, where the biological solids settle out. The clarified effluent flows to the
chlorination basins, where it is chlorinated using liquid sodium hypochlorite. The biologi cal
solids (liquid sludge) produced during secondary clarification are pumped to the small aerobic
digesters for a short stabilization period. The liquid sludge is then pumped to the control
building, where it is blended with polymer and dewatered using a belt filter press.
Descriptions of processes and further details of the WWTF are presented in Chapter 7.
NPDES Regulations and City Permit
The City has a National Pollutant Discharge Elimination System (NPDES) Permit issued by the
Washington State Department of Ecology (Ecology). The permit includes effluent limits for
treated water discharged to the City’s outfall in the Strait of Juan de Fuca in Puget Sound. In
addition, the permit includes facility flow and loading design criteria for the WWTF as shown in
Table ES-6.
Table ES-6
WWTF Permitted Flow and Loading Design Criteria
Compost Facility and Solids Handling
The Compost Facility has been successfully operating since 1993. Dewatered biosolids,
dewatered septage, and ground yard waste are composted to produce a product used for soil
conditioning. The City’s Compost Facility is covered under the general permit to produce Class A
biosolids as defined in the federal 40 CFR 503 regulations and is covered under a State Waste
Discharge Permit (SWDP). The SWDP effluent limits for the sequencing batch reactor (SBR) and
wetlands are shown in Tables ES-7 and ES-8.
Parameter Design Quantity
Maximum Month Design Flow (MMDF)2.05 MGD
Annual Average Flow 1.44 MGD
BOD 5 Influent Loading for Maximum Month 3,754 ppd
TSS Influent Loading for Maximum Month 4,568 ppd
Design Population 12,000
MGD = million gallons per day
ppd = pounds per day
EXECUTIVE SUMMARY CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table ES-7
SWDP SBR Effluent Limits
Table ES-8
SWDP Wetland Effluent Limits
Existing Wastewater Flow and Loading
Flow and load values in a sewer system are used to determine the size of gravity collection
piping, lift station facilities, and force main piping, and the size and type of treatment facilities
needed. This information also is used to develop the sewer service provider’s NPDES Permit,
which is required by Ecology. Chapter 4 presents the historical and projected WWTF flow and
loading rates.
The total influent flow to the WWTF is made up of wastewater flow from primarily residential
customers but also includes flow from a number of commercial, hospitality, and retail
businesses, schools, and the Jefferson Healthcare Medical Center. The historical 2016 through
2021 influent average annual flow (AAF), maximum month average flow (MMF), and maximum
day flow (MDF) (including infiltration and inflow) is summarized in Table ES-9. The 2021 AAF
was 0.84 million gallons per day (MGD).
Parameter Average Monthly Average Weekly
BOD 5
30 mg/L
1 ppd
85% removal of influent BOD 5
45 mg/L
1.5 ppd
TSS
30 mg/L
1 ppd
85% removal of influent TSS
45 mg/L
1.5 ppd
Parameter Minimum Maximum
pH 6.0 standard units 9.0 standard units
Parameter Monthly Geometric Mean 7-Day Geometric
Mean
Fecal Coliform 200 col/100 mL 400 col/10 mL
Parameter Average Monthly Average Weekly
Total Residual Chlorine 0.5 mg/L 0.75 mg/L
Parameter Average Monthly Average Weekly
Nitrate 10 mg/L as N -
Effluent Limits: Wetland Influent
Effluent Limits: Wetland Effluent
CITY OF PORT TOWNSEND GENERAL SEWER PLAN EXECUTIVE SUMMARY
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Table ES-9
Historical WWTF Influent Flow Summary
Table ES-10 summarizes the historical 5-day biochemical oxygen demand (BOD5), and
Table ES-11 summarizes the historical total suspended solids (TSS) loadings for 2016 through
2021 in pounds per day (ppd) and pounds per capita per day (ppcd).
Table ES-10
Historical WWTF Influent BOD5 Loading Summary
Table ES-11
Historical WWTF Influent TSS Loading Summary
MMF/AAF MDF/AAF PHF/AAF
2016 9,414 0.85 91 1.07 1.99 --52%1.26 2.33 --
2017 9,480 0.84 88 0.92 1.39 2.79 45%1.10 1.66 3.33
2018 9,559 0.87 91 1.16 1.82 3.06 57%1.33 2.09 3.52
2019 9,669 0.78 81 0.87 1.12 2.35 43%1.11 1.43 2.99
2020 9,757 0.80 82 1.15 2.37 3.34 56%1.43 2.96 4.17
2021 9,829 0.84 85 1.02 2.18 ---50%1.22 2.60 ---
0.84 88 1.01 1.58 2.74 --1.20 1.88 3.28
0.87 91 1.16 1.99 3.06 --1.33 2.33 3.52
AAF
(MGD)
Sewer System
PopulationYear
Peaking Factors
Percent of NPDES
Permit Max. Month
Limit1
PHF
(MGD)
1 = The City's WWTF is permitted for a maximum month average influent flow of 2.05 MGD.
2 = 2020 and 2021 values are not included in the historical averages and maximums due to the COVID pandemic.
2016 to 2019 Average2
2016 to 2019 Max.2
MDF
(MGD)
MMF
(MGD)
AAF per
Capita
(gpcd)
Year
Sewer System
Population
Average
Annual
BOD5
(mg/L)
Average
Annual
BOD5
(ppd)
Average Annual
BOD5
(ppcd)
Max. Month
BOD5
(mg/L)
Max.
Month
BOD5
(ppd)
Percent of NPDES
Permit Max.
Month Limit1
BOD5 Max. Month
Average/Average
Annual Peaking
Factor
2016 9,414 332 2,242 0.24 405 2,442 65%1.09
2017 9,480 329 2,289 0.24 364 2,538 68%1.11
2018 9,559 363 2,509 0.26 454 2,968 79%1.18
2019 9,669 400 2,591 0.27 437 2,718 72%1.05
2020 9,757 336 2,147 0.22 374 2,422 65%1.13
2021 9,829 334 2,221 0.23 393 2,500 67%1.13
356 2,408 0.25 415 2,667 ---1.11
400 2,591 0.27 454 2,968 ---1.18
2016 to 2019 Average2
2016 to 2019 Max.2
1 = The City's WWTF is permitted for a maximum month BOD5 influent loading of 3,754 ppd.
2 = 2020 and 2021 values are not included in the historical averages and maximums due to the COVID pandemic.
Year
Sewer System
Population
Average
Annual
TSS
(mg/L)
Average
Annual
TSS
(ppd)
Average Annual
TSS
(ppcd)
Max.
Month
TSS
(mg/L)
Max.
Month
TSS
(ppd)
Percent of NPDES
Permit Max. Month
Limit1
TSS Max. Month
Average/Average
Annual Peaking
Factor
2016 9,414 331 2,240 0.24 388 2,458 54%1.10
2017 9,480 329 2,291 0.24 367 2,564 56%1.12
2018 9,559 359 2,493 0.26 431 2,799 61%1.12
2019 9,669 376 2,437 0.25 417 2,686 59%1.10
2020 9,757 341 2,188 0.22 386 2,725 60%1.25
2021 9,829 322 2,146 0.22 390 2,481 54%1.16
349 2,365 0.25 401 2,627 ---1.11
376 2,493 0.26 431 2,799 ---1.12
2016 to 2019 Average2
2016 to 2019 Max.2
1 = The City's WWTF is permitted for a maximum month TSS influent loading of 4,568 ppd.
2 = 2020 and 2021 values are not included in the historical averages and maximums due to the COVID pandemic.
EXECUTIVE SUMMARY CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Inflow and Infiltration
Inflow and infiltration is the combination of groundwater and surface water that enters the
sewer system. The U.S. Environmental Protection Agency (EPA) published a report in May 1985,
Infiltration/Inflow, I/I Analysis and Project Certification, that developed guidelines to help
determine what amount of inflow and infiltration (I/I) is considered to be excessive and what
amount can be cost-effectively removed.
Inflow is considered to be non-excessive if the average daily flow during periods of heavy
rainfall or spring thaw does not exceed 275 gallons per capita per day (gpcd). The peak
recorded flow data in the 6 years of data analyzed for the City was 2.37 MGD. This peak inflow
event equates to 243 gpcd, which is below the EPA’s maximum guideline of 275 gpcd. The City
did not experience any peak inflow events above the EPA’s maximum inflow criterion. The City
should continue to monitor inflow throughout the system, particularly in areas over 50 years
old that previously may have been combined collection systems.
The determination of non-excessive infiltration was based on the national average for dry
weather flow of 120 gpcd. In order for the amount of infiltration to be considered
non-excessive, the average daily flow must be less than 120 gpcd. The peak dry weather flow
period in the last 6 years (2016 through 2021) of record for the City, occurring after a few
consecutive days of rain, was the 5-day period from January 22 through January 26, 2016. This
period also was directly preceded by heavy rains, and yielded an average flow of 1.20 MGD,
equating to 128 gpcd. The second highest peak dry weather flow period occurred in February
2018 and yielded an average flow of 124 gpcd. The third highest peak dry weather flow period
occurred during a 14-day period in February 2020, resulting in an average flow of 121 gpcd. All
three events are slightly above the EPA’s maximum infiltration criterion; therefore, the amount
of infiltration is considered excessive. The City should continue to monitor infiltration
throughout the system.
Peaking Factors
Projected flows are used to analyze how well the existing sewer system will perform in the
future and determine improvements required to maintain or improve system function. Peaking
factors are needed to establish projected flow scenarios f or the sewer system, which are then
applied to future flow rates. Table ES-12 shows a summary of peaking factors for flows at the
City’s WWTF for the 2016 through 2021 period.
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Table ES-12
WWTF Peaking Factor Summary for Flows
Peaking factors also are developed to determine maximum month average BOD5 and TSS
loading projections, as shown in Table ES-13. These loading peaking factors are the average
historic maximum month to average annual loadings from 2016 to 2019. Data obtained during
the COVID pandemic (2020 and 2021) may not represent normal flow and load conditions.
Table ES-13
WWTF Peaking Factor Summary for Loadings
Projected Wastewater Flow
The City’s sewer system is projected to add a total of 5,683 additional persons by 2043 using
2018 as the base year. Table ES-14 provides a summary of the projected flows for the WWTF.
According to these projections, the WWTF will not exceed the NPDES permit maximum month
limit capacity during the 20-year planning period. However, the City should evaluate the WWTF
for upgrades when the average MMF exceeds 85 percent of the NPDES Permit limit. According
to these projections (based on flow), the City should prepare for WWTF upgrades by 2038.
Max. Month Average Flow/Average Annual Flow (MMF/AAF)1.33
Max. Day Flow/Average Annual Flow (MDF/AAF)1 2.83
Peak Hour Flow/Average Annual Flow (PHF/AAF)1 4.00
Max. Month Average/Average Annual Loading 1.18
Max. Month Average/Average Annual Loading 1.12
Flow
BOD5
TSS
1 = The MDF and PHF for 2016 through 2021 both occurred in 2020 during the COVID pandemic. 2020
had a lower than typical AAF, so the PHF/AAF and MDF/AAF peaking factors were estimated with the
PHF and MDF from this year divided by the average AAF for 2016 through 2019.
Year
BOD5 Max. Month
Average/Average
Annual Peaking Factor
TSS Max. Month
Average/Average
Annual Peaking Factor
2016 1.09 1.10
2017 1.11 1.12
2018 1.18 1.12
2019 1.05 1.10
2020 1.13 1.25
2021 1.13 1.16
Average1 1.11 1.11
1 = The peaking factors used for projections are the averages of the peaking
factors from 2016 to 2019. 2020 and 2021 values are not included in these
averages due to the COVID pandemic.
EXECUTIVE SUMMARY CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table ES-14
Total Projected WWTF Flow including Special Study Area Expansion
Projected Wastewater Quality
Projected BOD5 and TSS loadings are presented in Tables ES-15 and ES-16. According to these
projections, the WWTF will exceed the NPDES Permit maximum month limit capacity for BOD5
during the 20-year planning period. However, the City should prepare the WWTF for upgrades
when the maximum month average BOD5 load exceeds 85 percent of the NPDES permit limit.
According to these projections (based on BOD load), the City should begin planning and
preparing for WWTF upgrades by 2027. Near-term upgrades will be completed to enable the
City to reach 100-percent capacity. However, the WWTF will not exceed the NPDES Permit
maximum month limit capacity for TSS during the 20-year planning period. The City should
prepare the WWTF for upgrades when the maximum month average TSS load exceeds
85 percent of the NPDES Permit limit. According to these projections, the City should prepare
for WWTF upgrades for TSS by 2041. Capital improvement plan projects for WWTF upgrades
are included in Chapter 10.
Year
Equivalent Sewer
System
Population
Projected AAF1
(MGD)
Projected MMF2
(MGD)
Percent of NPDES
Permit Max.
Month Limit3
Projected MDF4
(MGD)
Projected PHF5
(MGD)
Projected PHF with
Inflow Reduction6
(MGD)
2018 (Baseline)9,559 0.87 1.16 57%1.82 3.06 --
2019 9,669 0.78 0.87 43%1.12 2.35 --
2020 9,757 0.80 1.15 56%2.37 3.34 --
2021 9,829 0.84 1.02 50%2.18 -----
2022 9,981 0.91 1.21 59%2.57 3.63 --
2023 10,134 0.92 1.23 60%2.61 3.69 --
2024 10,289 0.94 1.25 61%2.65 3.75 --
2025 10,553 0.96 1.29 63%2.73 3.87 --
2026 10,819 0.99 1.32 65%2.81 4.00 --
2027 11,086 1.02 1.36 66%2.89 4.13 --
2028 11,354 1.05 1.40 68%2.97 4.26 --
2029 11,624 1.08 1.44 70%3.05 4.39 --
2030 11,896 1.11 1.47 72%3.13 4.52 --
2031 12,169 1.13 1.51 74%3.21 4.65 --
2032 12,444 1.16 1.55 76%3.29 4.78 --
2033 (+ 10 years)12,720 1.19 1.59 78%3.38 4.91 4.50
2034 12,927 1.21 1.62 79%3.44 5.01 4.59
2035 13,140 1.24 1.65 80%3.50 5.10 4.69
2036 13,361 1.26 1.68 82%3.56 5.20 4.79
2037 13,603 1.28 1.71 83%3.64 5.31 4.90
2038 13,853 1.31 1.75 85%3.71 5.42 5.01
2039 14,111 1.34 1.78 87%3.79 5.54 5.13
2040 14,379 1.36 1.82 89%3.86 5.66 5.25
2041 14,656 1.39 1.86 91%3.95 5.79 5.38
2042 14,944 1.42 1.90 93%4.03 5.92 5.51
2043 (+ 20 years)15,242 1.46 1.94 95%4.12 6.06 5.65
Buildout 25,806 2.39 3.19 156%6.77 9.82 9.40
1 = Total projected AAF was estimated by adding City limit and sewer system expansion flows together.
2 = Total projected MMF was estimated by adding City limit and sewer system expansion flows together.
3 = The City's WWTF is permitted for a maxium month average influent flow of 2.05 MGD.
4 = Total projected MDF was estimated by adding City limit and sewer system expansion flows together.
5 = Total projected PHF was estimated by adding City limit and sewer system expansion flows together.
6 = Projected PHFs with inflow reduction were estimated by reducing projected PHFs after 2032 by 288 (0.41 MGD) to account for the removal of inflow estimated to be contributed by catch basins connected
to the City's sewer system along Lawrence Street.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN EXECUTIVE SUMMARY
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Table ES-15
Total Projected WWTF BOD5 Loading including Special Study Area Expansion
Year
Equivalent Sewer
System
Population
Projected Average
Annual BOD5
(ppd)1
Projected Max.
Month Average
BOD5
(ppd)2
Percent of NPDES
Permit Max.
Month Limit3
2018 9,559 2,509 2,968 79%
2019 (Baseline)9,669 2,591 2,718 72%
2020 9,757 2,147 2,422 65%
2021 9,829 2,221 2,500 67%
2022 9,981 2,654 2,939 78%
2023 10,134 2,684 2,973 79%
2024 10,289 2,715 3,007 80%
2025 10,553 2,768 3,066 82%
2026 10,819 2,821 3,125 83%
2027 11,086 2,875 3,184 85%
2028 11,354 2,928 3,243 86%
2029 11,624 2,982 3,303 88%
2030 11,896 3,037 3,363 90%
2031 12,169 3,091 3,424 91%
2032 12,444 3,146 3,485 93%
2033 (+ 10 years)12,720 3,202 3,546 94%
2034 12,927 3,243 3,592 96%
2035 13,140 3,286 3,639 97%
2036 13,361 3,330 3,688 98%
2037 13,603 3,378 3,741 100%
2038 13,853 3,428 3,797 101%
2039 14,111 3,480 3,854 103%
2040 14,379 3,533 3,913 104%
2041 14,656 3,589 3,975 106%
2042 14,944 3,646 4,039 108%
2043 (+ 20 years)15,242 3,706 4,105 109%
Buildout 25,806 5,819 6,445 172%
1 = Projected average annual BOD 5 loadings were estimated by adding City limit and sewer system expansion loadings together.
2 = Projected maximum month average BOD 5 loadings were estimated by adding City limit and sewer system expansion loadings
together.
3 = The City's WWTF is permitted for a maximum month average influent BOD 5 loading of 3,754 ppd.
EXECUTIVE SUMMARY CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table ES-16
Total Projected WWTF Influent TSS Loading including Special Study Area Expansion
Policies and Design Criteria
The City operates and plans sewer service for the City and associated sewer service area
residents and businesses according to the design criteria, laws, and policies that originate from
the EPA and Ecology.
These laws, design criteria, and policies guide the City’s operation and maintenance of the
sewer system on a daily basis, as well as the City’s plan for growth and improvements. The
overall objective is to ensure that the City provides high quality sewer service at a fair and
Year
Equivalent Sewer
System
Population
Projected Average
Annual TSS
(ppd)1
Projected Max.
Month Average
TSS
(ppd)2
Percent of NPDES
Permit Max.
Month Limit3
2018 (Baseline)9,559 2,493 2,799 61%
2019 9,669 2,437 2,686 59%
2020 9,757 2,188 2,725 60%
2021 9,829 2,146 2,481 54%
2022 9,981 2,577 2,862 63%
2023 10,134 2,608 2,896 63%
2024 10,289 2,639 2,930 64%
2025 10,553 2,692 2,989 65%
2026 10,819 2,745 3,048 67%
2027 11,086 2,798 3,107 68%
2028 11,354 2,852 3,167 69%
2029 11,624 2,906 3,227 71%
2030 11,896 2,960 3,287 72%
2031 12,169 3,015 3,347 73%
2032 12,444 3,070 3,408 75%
2033 (+ 10 years)12,720 3,125 3,470 76%
2034 12,927 3,167 3,516 77%
2035 13,140 3,209 3,563 78%
2036 13,361 3,253 3,612 79%
2037 13,603 3,302 3,666 80%
2038 13,853 3,352 3,721 81%
2039 14,111 3,403 3,779 83%
2040 14,379 3,457 3,838 84%
2041 14,656 3,513 3,900 85%
2042 14,944 3,570 3,964 87%
2043 (+ 20 years)15,242 3,630 4,030 88%
Buildout 25,806 5,742 6,376 140%
1 = Projected average annual TSS loadings were estimated by adding City limit and sewer system expansion loadings together.
2 = Projected maximum month average TSS loadings were estimated by adding City limit and sewer system expansion loadings
together.
3 = The City's WWTF is permitted for a maximum month average influent TSS loading of 4,568 ppd.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN EXECUTIVE SUMMARY
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reasonable cost to its customers. They also set the standards the City must meet to ensure that
the sewer system is adequate to meet existing and future flows. The collection system’s ability
to handle these flows is detailed in Chapter 6, and the recommended improvements are
identified in Chapter 10. The City Council adopts regulations and policies. The City’s policies
cannot be less stringent or in conflict with those established by federal and state governments.
The City’s policies take the form of ordinances, memoranda, and operational procedures, many
of which are summarized in Chapter 5.
The City will maintain an updated GSP that is coordinated with the Land Use Element of the
City’s Comprehensive Plan, so that new development will be located where sufficient sewer
system capacity exists or can be efficiently and logically extended.
Operation and Maintenance
Chapter 9 addresses the operation and maintenance (O&M) staff for the City’s WWTF and
collection system. Currently, there are approximately 8 personnel funded and assigned to the
O&M of the City’s sewer system.
The collection system and WWTF will continue to expand with population growth, and the City
will need additional staff to continue maintaining the gravity sewers, force mains, and lift
stations. For O&M needs, the City recommends a total of 2.6 full-time employees (FTEs) for the
wastewater collections. The City also has requested and is planning to add 1.0 FTE for the
WWTF and Compost Facility. This results in a total of approximately 10 FTEs for the O&M of the
City’s sewer system.
Summary of Improvements
A general description of improvements and an overview of the deficiencies they will resolve are
presented in Chapter 10. Some of the improvements are necessary to resolve existing system
deficiencies. The sewer system improvements were identified from the results of the collection
system evaluation presented in Chapter 6 and the WWTF and Compost Facility evaluation
presented in Chapters 7 and 8. The sewer system improvements were sized to meet the
system’s projected 2043 demand conditions.
Collection system improvements to accommodate new growth are not shown in detail in this
CIP. It is assumed that most of the new growth will occur at or near the Mill site. This CIP
includes a lift station to allow development of the Mill site and conveyance for the new lift
station’s discharge throughout the existing collection system.
It is intended that this GSP contain an inclusive list of recommended system improvements;
however, additional projects may need to be added or removed from the list as growth occurs
or conditions change. The City will evaluate the capacity of the wastewater collection system,
WWTF, and Compost Facility as growth occurs and as development permits are received.
Project costs for the proposed improvements were estimated based on costs of similar recently
constructed sewer projects around the Puget Sound area and are presented in 2023 dollars.
The cost estimates include the estimated construction costs and indirect costs. The existing
system improvements were prioritized by the City based on a perceived need for the
EXECUTIVE SUMMARY CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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improvement to be completed prior to projects with fewer deficiencies or less risk of damage
due to failure of the system. A general schedule has been established for planning purposes;
the schedule should be modified based on City preferences, budget, or as development
fluctuates. In addition, the City retains the flexibility to reschedule, expand, or reduce the
projects presented in Table ES-17 when new information becomes available for review and
analysis.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN EXECUTIVE SUMMARY
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Table ES-17
Proposed CIP Implementation Schedule
Estimated
CIP Length Cost
No.(LF)(2023 $)2024 2025 2026 2027 2028 6-10 years 11-20 years
SM1 786 $1,212,000 $100K $606K $506K
SM2 1,079 $1,578,000 $1,578K
SM3 796 $1,186,000 $1,186K
SM4 531 $819,000 $819K
SM5 1,685 $2,463,000 $2,463K
SM6 West Sims Way and 3rd Street 1,149 $1,679,000 $1,679K
SM7 Future Interceptor Upsizing 3,785 $6,722,000 $6,722K
SM8 --$3,300,000 $150K $350K $350K $350K $350K $1,750K
SM9 Lawrence Street Combined Sewer Separation*1,800 $2,826,000 $500K $1,163K $1,163K
SM10 Suitcase Pipe Replacement on Washington Street 303 $399,000 $399K
SM11 Long-Term Sewer System Investigation and Refurbishment**--$56,000,000 $56,000K**
SM12 Water Street Sewer Replacement 1,600 $2,100,000 $2,100K
$80,284,000 $2,350K $1,855K $2,019K $1,513K $350K $5,333K $66,864K
WW1 $5,000,000 $500K $4,500K
WW2 $300,000 $300K
WW3 $1,000,000 $50K $50K $50K $50K $50K $250K $500K
WW4 $6,300,000 $1,100K $3,200K $2,000K
$12,600,000 $1,450K $3,250K $2,050K $50K $550K $4,750K $500K
F1 $2,120,000 $300K $1,820K
F2 $1,200,000 $1,200K
F3 $1,250,000 $1,250K
F4 $1,250,000 $1,250K
F5 $120,000 $60K $60K
F6 $1,140,000 $150K $990K
F7 $630,000 $630K
F8 $2,940,000 $100K $400K $2,440K
F9 $4,000,000 $500K $600K $2,900K
F10 $3,000,000 $3,000K
F11 $2,000,000 $2,000K
F12 $30,000,000 $30,000K
$49,650,000 $860K $4,670K $4,580K $0K $400K $9,140K $30,000K
C1 $890,000 $160K $365K $365K
C2 $700,000 $150K $130K $130K $130K $160K
C3 $460,000 $460K
C4 $390,000 $390K
C5 $80,000 $19K $19K $19K $23K
C6 $410,000 $15K $395K
C7 $670,000 $100K $285K $285K
C8 $300,000 $300K
$3,900,000 $479K $974K $594K $803K $495K $160K $395K
M1 $90,000 $90K
M2 $2,850,000 $100K $2,750K
M3 $250,000 $250K
M4 $250,000 $250K
$3,440,000 $0K $440K $0K $0K $0K $2,750K $250K
$149,874,000 $5,139K $11,189K $9,243K $2,366K $1,795K $22,133K $98,009K
*50% cost shown in the CIP table. It is assumed an additional 50% will be paid by the Road and Storm Drainage departments.
**Costs are budgetary for pipe replacement of unknown materials. As the City video inspects the system and updates condition, this is subject to change. Rate analysis only includes anticipated grants to reduce City expenditure to $21 million.
Compost Screen Replacement
Solids Handling Tank Replacement and Mechanical Upgrades
Wastewater Treatment Facility Improvements
Mill Lift Station
Existing Monroe Street Lift Station Improvements
Sewer Camera Van, Video Camera and Tractor, Recording Software and Hardware, and Staff Training
Total - Lift Station Improvements
General Lift Station Improvements
Influent Pump Station and Odor Control Improvements
Headworks Rehabilitation
Clarifier No. 2 Improvements
Compost Facility and Solids Handling Improvements
Solids Handling Influent Screening and Grit Removal
Electrical Upgrades
Outfall Upgrades
Clarifier No. 1 Improvements
Howard Street and S Park Avenue
Sims Way, 3rd Street, and Gise Street
Total - Sewer Main Improvements
Lift Station Improvements
Howard Street, S Park Avenue, and McPherson Street
Sewer System Defect Investigation and Repair
Holcomb Street
Project Description
Sewer Main Improvements
Sims Way Crossing and Wilson Street Realignment
Compost Case Loader Replacement
Public Works Shop - Sewer Collection Share
General Sewer Plan Update
Total - Miscellaneous Improvements
Total Estimated Project Costs of City-funded Improvements
Compost Blowers Replacements
Compost Facility Infrastructure Upgrades
6-inch Hydrant Line
Office with Dedicated Lunchroom
Total - Facility Improvements
Miscellaneous and Planning Improvements
Arc Flash Analysis
Downtown Restrooms
Near-Term Oxidation Ditch Improvements
Non-Potable Water Pump Replacements (City to Install)
SCADA Upgrades
Total - Facility Improvements
Land Acquisition for WWTF Expansion
Long-Term WWTF Expansion (Budgetary Estimate)
On-Site Solids Handling Improvements
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1 | INTRODUCTION
SEWER SYSTEM OWNERSHIP AND MANAGEMENT
The City of Port Townsend (City), located in Jefferson County (County), is a municipal
corporation that provides wastewater collection and treatment, among other municipal
services. The City owns, operates, and maintains the sewer system. Ownership information ,
including the owner’s authorized representative, is as follows.
Physical Address:
250 Madison Street, Suite 2R
Port Townsend, WA 98368
Authorized Representative Name and Phone Number: City Manager, John Mauro,
(360) 349-5043
Operation and management of the sewer system is provided by the wastewater division of the
City’s Public Works Department with the following contacts:
• City Public Works Director, Steve King, (360) 379-5090
• Wastewater Treatment and Compost Operations Manager, Bliss Morris, (360) 344-3043
• Streets and Collection Operations Manager, Brian Reid, (360) 385-3197
OVERVIEW OF EXISTING SYSTEM
The City’s sewer system is comprised of a wastewater treatment facility (WWTF), 7 sewer lift
stations, and approximately 77.4 miles of gravity and force main pipes. The City also owns and
operates a Compost Facility for solids from the WWTF, and septage receiving station and
separate WWTF at the Compost Facility. The City provided wastewater collection and
treatment to an estimated 9,829 people in 2021, compared to the City’s population of 10,220.
Currently, 206 properties within the City limits are using on-site septic systems. As of 2021, the
City’s number of wastewater service customer connections was approximately 4,710. The City’s
sewer planning area is the same as its Urban Growth Area (UGA).
The main WWTF consists of an Influent Pump Station (IPS), headworks, oxidation ditches,
secondary clarifiers, and chlorine contact basins. Waste sludge is captured in the aerobic sludge
holding tanks and hauled to the City’s Compost Facility. The WWTF is permitted for a maximum
month average flow (MMF) of 2.05 million gallons per day (MGD). The Compost Facility
produces a Class A biosolids product for local beneficial use and handles some of the County’s
septage in a sequencing batch reactor with disinfection and disposal to constructed wetlands
and infiltration.
A summary of the City’s sewer system data is provided in Table 1-1.
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Table 1-1
2021 City Sewer System Data
AUTHORIZATION AND PURPOSE
The City authorized RH2 Engineering, Inc., (RH2) to prepare a General Sewer Plan (GSP) in
accordance with Washington Administrative Code (WAC) 173-240-050. The previous
Wastewater Comprehensive Plan was prepared by CH2MHILL for the City in 1999 and was
approved by the Washington State Department of Ecology (Ecology) in 2000. In addition, a
Wastewater Facilities Plan was completed in 2000 by Gray & Osborne, Inc., to address Ecology
comments on the Wastewater Comprehensive Plan and focus on major system components
with a capital program.
The purpose of this updated GSP is as follows:
• To update the City’s GSP for consistency with the future population and employment
growth projections from the City’s Planning and Community Development Department.
• To evaluate existing sewer flow and loading data and project future flows and loadings.
• To analyze the existing sewer system to determine if it meets minimum requirements
mandated by Ecology and the City’s own policies and design criteria.
• To determine the overall reliability and vulnerability of the existing wastewater lift
stations.
• To evaluate the existing WWTF to determine if the treatment facility meets the City’s
National Pollutant Discharge Elimination System Permit requirements.
• To identify sewer system collection improvements that will resolve existing system
deficiencies and accommodate future needs of the system.
Description Data
City Population 10,220
Number of Properties on Septic Systems 211
Sewer System Population 9,829
Total Connections 4,710
Sewer Planning Area - UGA (Square Miles)7.4
Average Gallons per Capita per Day (gpcd)85
Average Annual Flow (MGD)0.84
Maximum Month Average Flow (MGD)1.02
Maximum Day Flow (MGD)2.18
Number of Lift Stations 7
Total Length of Gravity Main (Miles)75.2
Length of 8-inch-diameter Gravity Main (Miles)45.3
Total Length of Force Main (Miles)2.2
WWTF Permitted Maximum Month Average Flow (MGD)2.05
gpcd = gallons per capita per day
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• To identify WWTF improvements that will resolve existing system deficiencies and
accommodate future wastewater treatment needs.
• To prepare a schedule of improvements that meets the goals of the City’s financial
program.
PREVIOUS PLANNING EFFORTS
The following documents provide a history of the planning efforts involving the City’s sewer
system.
1999 Wastewater Comprehensive Plan
2000 Wastewater Facilities Plan
2009 Southwest Sewer Basin Study
2012 Mill Road Pump Station and Force Main Predesign Report
2019 Port Townsend Condition Assessment Summary Report
SUMMARY OF PLAN CONTENTS
A brief summary of the content of the chapters in this GSP is as follows:
• Chapter 1 introduces the reader to the City’s sewer system, the objectives of the GSP,
and the GSP organization.
• Chapter 2 presents the sewer service area and describes the existing sewer system.
• Chapter 3 presents related plans, land use, and population characteristics.
• Chapter 4 identifies existing wastewater flow and loading rates and projects future flow
and loading rates.
• Chapter 5 presents the City’s operational policies and design criteria.
• Chapter 6 discusses the wastewater collection system analyses and deficiencies.
• Chapter 7 discusses the existing WWTF and Compost Facility analyses and deficiencies.
• Chapter 8 evaluates future improvement needs for the WWTF and Compost Facility to
address existing and projected deficiencies.
• Chapter 9 discusses the City’s operations and maintenance program.
• Chapter 10 presents the proposed Capital Improvement Plan (CIP), including
wastewater collection system, WWTF, and Compost Facility improvements, their
estimated costs, and a schedule for implementation.
• Chapter 11 summarizes the financial status of the sewer utility and presents a plan for
funding the sewer improvements.
LIST OF ABBREVIATIONS
The abbreviations listed in Table 1-2 are used throughout this GSP.
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Table 1-2
Abbreviations
Abbreviation Description
AACE Association of Cost Engineers
AAF average annual flow
AC asbestos cement
AKART all known, available, and reasonable treatment
BOD5 5-day biochemical oxygen demand
CI cast iron
CIP Capital Improvement Plan
CIPP cured-in-place pipe
City City of Port Townsend
County Jefferson County
CWA Clean Water Act
DI ductile iron
DMR Discharge Monitoring Report
Ecology Washington State Department of Ecology
EPA U.S. Environmental Protection Agency
FRP fiberglass reinforced plastic
FTE full-time staff equivalents
GMA Growth Management Act
gpcd gallons per capita per day
GSP General Sewer Plan
HDPE high-density polyethylene
IFAS integrated fixed film activated sludge
I/I Inflow and Infiltration
IPS Influent Pump Station
LAMIRD local area of more intense rural development
lf linear feet
LID Local Improvement District
MABR membrane aeration biofilm reactors
MCC Motor Control Center
MDF maximum day flow
MG million gallons
MGD million gallons per day
mg/L milligrams per liter
MLE Modified Ludzach-Ettinger
MLSS mixed liquor suspended solids
MMDF maximum month design flow
MMF maximum month average flow
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Table 1-2
Abbreviations (Continued)
Abbreviation Description
MOB mobile organic biofilm
MUTCD Manual on Uniform Traffic Control Devices
NES National Electrical Code
NOP Nitrogen Optimization Plan
NPDES National Pollutant Discharge Elimination System
NPW non-potable water
OFM Office of Financial Management
O&M operations and maintenance
ORP oxidation-reduction potential
OSHA Occupational Safety and Health Administration
PHF peak hour flow
ppcd pounds per capita per day
ppd pounds per day
psi pounds per square inch
PSNGP Puget Sound Nutrient General Permit
PTMC Port Townsend Municipal Code
PVC polyvinyl chloride
RAS return activated sludge
RCW Revised Code of Washington
RH2 RH2 Engineering, Inc.
SBR sequencing batch reactor
SCADA supervisory control and data acquisition
SEPA State Environmental Policy Act
SLR solids loading rate
SRT solids retention time
SVI sludge volume index
SWDP State Waste Discharge Permit
TIN total inorganic nitrogen
TSS total suspended solids
UGA Urban Growth Area
VC vitrified clay
VFD variable frequency drive
WAC Washington Administrative Code
WAS waste activated sludge
WISHA Washington Industrial Safety and Health Act
WWTF wastewater treatment facility
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2 | SEWER SYSTEM DESCRIPTION AND DISCHARGE
REGULATIONS
INTRODUCTION
This chapter describes the City of Port Townsend’s (City) sewer service area, wastewater
collection and treatment system, lift stations, and discharge and disposal regulations and
permits. Included in this chapter is a brief overview of the City’s topography, geology, and
climate to provide a better understanding of the physical characteristics of the City. A brief
description of the City’s water system facilities also is presented.
Analysis of the existing sewer system is presented in Chapter 4. The results of the evaluation
and analyses of the existing sewer system are presented in Chapter 6. Evaluation of the existing
treatment facilities is presented in Chapter 7. Improvements to address treatment facility
deficiencies are presented in Chapter 8.
SEWER SERVICE AREA
History
The City's sewer system was originally constructed as combined wastewater and stormwater
sewers serving each small drainage area. There was no requirement for treatment of this
combined sewage, so there were many outfalls to Port Townsend Bay and Admiralty Inlet.
In the 1960s, the City responded to new Washington State requirements to provide primary
treatment for all combined sewage. Interceptors, lift stations, and the City’s first wastewater
treatment facility were constructed and placed in service, and the existing outfall was extended
in 1967.
In the early 1970s, the Federal Government established new standards requiring higher levels
of treatment for municipal wastewater. For most cities, including Port Townsend, these higher
standards meant that additional (secondary) treatment facilities would be required .
In 1976, the City completed a Wastewater Facilities Plan under the guidelines issued by the U.S.
Environmental Protection Agency. The plan evaluated the requirements to upgrade the facility
to secondary treatment and was approved by the Washington State Department of Ecology
(Ecology). The plan recommended adding sludge dewatering facilities and an oxidation ditch for
secondary treatment and conversion to secondary clarifiers. Upon completion of the plan, the
City applied for funding from Ecology to implement the plan. Ecology did not assist the City with
funding at that time; therefore, no improvements were made.
In 1982 and 1983, the City prepared and submitted an Application for Modification of
Secondary Treatment Requirements for Discharge into Marine Waters, as allowed under
Section 301(h) of the Clean Water Act. The waiver of secondary treatment was denied by state
and federal agencies.
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The City later entered into a consent agreement with Ecology to have secondary treatment
facilities operational by 1993. In 1987, engineering for upgrading the wastewater treatment
facility (WWTF) to secondary treatment began. In 1989 and 1990, several permit issues
surfaced and a citizens group filed an action against the City to stop construction. The City and
the citizens group worked cooperatively to resolve the permit issues through design changes.
The City commenced construction, and the new secondary wastewater treatment facility was
installed at the same site as the original plant. The new facility began service in July of 1993.
The City originally disposed of the biosolids produced by the WWTF at the Jefferson County
(County) landfill until 1991 when the landfill was closed. Biosolids were then hauled to
Bremerton as an interim biosolids disposal method. The City explored a number of alternative
methods for disposal of the generated biosolids and septage, ranging from forest application
and incineration to lime and kiln dust stabilization. After a detailed analysis and substantial
public involvement, composting was chosen as the preferred approach to bi osolids
management. The Compost Facility has been successfully operating since 1993. Dewatered
biosolids, dewatered septage, and yard waste are composted to produce a product used for soil
conditioning. The finished compost meets federal 40 CFR 503 regulations for a class A product
and is thus allowed for unrestricted use.
The City has been growing steadily since the original interceptors, lift stations, and WWTF were
constructed in 1967. Since that time, improvements to the collection system have consisted of
regular maintenance and repair activities at the lift stations and expansion of the collection
system to serve unsewered areas. Most of the collection system improvements identified in the
2000 Wastewater Facilities Plan have been completed. The work performed over the last
20 years was funded through loan and grant contributions, along with sewer rates. Figure 2-1
shows the extents of the sewer collection system.
Geology
The soils in the Port Townsend area are primarily of the Clallam-Hoypus-Dick association, which
are composed of gravel, loam, and sand. These soils vary from 20 to 60 inches in depth, and
most areas are well drained. Compact gravelly sand and glacial till underlie these soils. Till is a
deposit of unsorted material that has been densely compacted under the weight of a glacier.
The City’s service area has undergone repeated glacial advances and retreats until as recently
as 10,000 years ago. Glacial till is relatively impermeable and is the cause of many on-site septic
system problems over the years. There are many small, isolated areas across the City where the
glacial till is exposed and the soils are poorly drained. Drainage in these areas is problematic
with many perched, wet areas that further complicate the application of on -site septic systems.
Topography
Figures 2-2 and 2-8 show the topography and natural drainage basins with the City limits. The
City has several high hills and steep bluffs, and elevations range from sea level to just over
300 feet. The undulating topography creates many isolated areas of low spots. These areas can
be challenging to sewer with gravity mains, but in general, the large amount of relief over the
City allows many sewers to be placed at steeper than minimum grades, reducing required
sewer sizes and the required time for wastewater to get to the treatment facility.
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Unfortunately, there are several areas that drain naturally to local low points away from the
WWTF, where lift stations already exist or may be necessary in the future to provide sewer
service to those areas.
Climate
The northern end of the Quimper Peninsula, where the City is located, does not typically
receive heavy precipitation common in other parts of the Olympic Peninsula and Puget Sound
lowlands. The City lies in the rain shadow of the Olympic Mountains. As a result, the City
receives relatively little precipitation in the summer months when prevailing winds are from the
west. The majority of the City’s annual precipitation occurs in the winter months when most
weather patterns pass over the City from the south. The City’s average annual minimum and
maximum precipitation are approximately 12 inches and 27 inches, respectively. Av erage daily
minimum and maximum precipitation ranges from approximately 0.4 to 0.8 inches per day,
respectively.
Sea Level Rise
The City and the County joined forces to develop a Climate Action Committee. This committee
has worked diligently to develop several reports and studies associated with the following:
• Modeling County carbon dioxide equivalent emissions with the goal of reducing and
measuring greenhouse gas emissions produced in the County overtime.
• Addressing the need to adapt to climate change in terms of impacts to weather patterns
and the hydrology of the area.
• Addressing the impacts of Sea Level Rise and developing forecasting tools to assess the
impacts of Sea Level Rise on City infrastructure.
The City of Port Townsend Sea Level Rise and Coastal Flooding Risk Assessment (2022, City of
Port Townsend and Cascadia Consulting Group) (Appendix K) incorporates the best available
science and information concerning climate change, and specifically Sea Level Rise, on the City’s
sewer infrastructure. In particular, Sea Level Rise will impact the City’s WWTF, three sewer lift
stations, and the City’s collection system over the next 100 years. Infrastructure planning for
these facilities incorporates this understanding, with the long-term goal of moving or
transitioning sewer facilities to become more resilient to Sea Level Rise. The City already has
experienced impacts of king tides, with one of the largest king tides occurring on
December 27, 2022. This king tide event flooded a portion of the Port of Port Townsend Boat
Haven Marina boat yard and contributed to the collapse of an asbestos cement (AC) gravity
sewer pipe, which settled due to a high water table caused by the king tide and the backup of
water into the storm system directly above the AC pipe. None of the City’s lift stations incurred
damage, but this event illustrates how close the City is to experiencing the effects of Sea Level
Rise combined with a king tide event.
Water Bodies and Floodplains
The City is bounded by the Salish Sea with Port Townsend Bay to the south, Admiralty Inlet to
the east, and the Strait of Juan de Fuca to the north. The natural drainage basins within the
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sewer service area drain primarily to the sea, Kah Tai Lagoon, or Ch inese Gardens Lagoon.
These natural drainage basins are shown in a figure from the City’s 2019 Stormwater
Management Plan in Appendix A. Both the Kah Tai and the Chinese Gardens Lagoons are
somewhat tidally influenced through pipe connections to the Salish Sea. There are no rivers or
streams located within the City limits, although there are a number of small, natural pon ds or
depressions throughout the area, as well as several wetlands. The City’s 2019 Stormwater
Management Plan addresses how surface water is dealt with within the City. A map of the
existing stormwater facilities is presented in Appendix A.
A small portion of the City is located within the 100-year floodplain along its marine shorelines,
including the Port of Port Townsend’s Point Hudson and Boat Haven, Kah Tai Lagoon, and the
Lincoln Beach area. Furthermore, there are several small wetlands and riparian areas
throughout the City. These sensitive areas and steep slopes limit the buildable area.
Given the City is surrounded by the Salish Sea, the City coordinates with the County Marine
Resources Council and the City’s Climate Action Committee concerning sewer project impacts
to the Salish Sea and/or the impacts of the sea on the operations and dev elopment of the
sewer system.
City Limits, Urban Growth Area, and Sewer Service Area Boundary
The sewer service area coincides with the Urban Growth Area (UGA) boundary, which is also
the City limits, and encompasses an area of approximately 7.4 square miles. The majority of the
developed area within the City limits is currently served by the City’s existing sewer system.
Within the sewer service area, approximately 5 percent of residences are served by privately
owned and operated on-site sewage systems (i.e. septic tanks with drain fields). Currently,
211 properties within the City limits are on on-site systems. The City’s sewer planning area
(i.e. future sewer service area) includes the City’s UGA (Figure 2-1).
The Glen Cove area directly adjacent and southwest of the City limits has been designated as a
Special Study Area for possible future inclusion in the City’s service area. The primary basis for
allowing this area to be incorporated into the City sewer service area is based on the following
factors:
1. The Glen Cove industrial area is a Type 3 Local Area of More Intense Rural Development
(LAMIRD) intended for light industrial and limited commercial use that could benefit
from the presence of sewer. Currently, all uses in this area are required to have an
on-site septic system, which may be limiting industrial activities and potentially resulting
in environmental degradation. LAMIRDs are permitted to be served by sanitary sewer
per the Growth Management Act (Washington Administrative Code (WAC)
365-196-425(6)(c), Rural Element).
2. In this area, the Port Townsend Paper Mill currently has an industrial waste treatment
system and a domestic waste treatment system, both of which discharge to Port
Townsend Bay. The City may consider allowing the domestic system to connect to the
City’s sewer system for the environmental benefit of eliminating a discharge to Port
Townsend Bay. This option would need to be approved by Ecology and the Department
of Commerce before executing a sewer service agreement for the Paper Mill.
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3. Through a UGA expansion or swap in cooperation with the County. Based on existing,
more intense development patterns, the Glen Cove Area may be deemed a key area to
serve existing and future uses to support the local economy given the lack of industrially
zoned properties and the need for housing within the City. An additional 20-acre parcel
directly adjacent to the City is owned by the County and is serving as a homeless
shelter. This parcel serves key public needs of providing for the poor and infirm. Sewer
service to this property may be of great benefit to the community and may serve as a
basis for a UGA expansion.
4. A portion of the area within the Glen Cove drainage basin is already in the City limits and
does not have access to sewer without the installation of a sewer lift station. Therefo re,
locating a sewer lift station in an appropriate area that keeps options open will allow the
City to make sewer service available for unsewered areas within the City limits while
allowing Factors 1 through 3 above to be considered.
All four of these factors involve the City and County working closely together to evaluate
impacts of sewer extension. The purpose of the Special Study Area is to document the sewer
basin planning process performed in 2012 as outlined in the Mill Road Pump Station and Force
Main Predesign Report (Appendix B). The City has funding to site a lift station in the Mill Road
area to serve the current UGA. Siting of this lift station , which could serve as described above, is
an important consideration for this Special Study Area to guide public investment of
approximately $4 million.
This General Sewer Plan (GSP) will address service needs in the Glen Cove Area and account for
Glen Cove’s possible future inclusion in the UGA.
EXISTING SEWER FACILITIES
The City owns, operates, and maintains the wastewater system, which includes a gravity
collection and conveyance system, seven wastewater lift stations, force mains, a WWTF, and an
outfall.
Sewer Drainage Basins
The City’s existing sewer service area is comprised of 14 sewer drainage basins that flow by
gravity to the 7 lift stations and WWTF, as shown in Figure 2-2.
The wastewater from the eastern part of the City is conveyed by the Point Hudson Lift Station
and the Monroe Lift Station, where flow is then conveyed to the Gaines Street Lift Station
before traveling by gravity main to the City’s WWTF. In other words, all of the sewer flow from
uptown, downtown, and the eastern shoreline is routed through the Gaines Street Lift Station.
Southern flows from the Port Lift Station also are conveyed to the Gaines Street Lift Station
before reaching the City’s WWTF. Wastewater from the western portion of the City is conveyed
to the Hamilton Heights Lift Station and the 31st Street Lift Station, which both then route
wastewater flows by gravity to the WWTF. A small portion of wastewater in the southwestern
portion of the City is sent to the Island Vista Lift Station, where it then flows by gravity to the
WWTF. All other wastewater collected in the City flows via gravity to the WWTF, where it is
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pumped to the outfall. Figure 2-3 shows a schematic representation of the general location and
flow path for each of the primary sewer drainage basins.
Figure 2-3
Sewer Drainage Basins Schematic
Gravity Sewer Collection Piping
The City has 75.2 miles of gravity sewer piping, including collection sewers and interceptors and
treated effluent sewers from the WWTF. A majority of the system is 8-inch-diameter gravity
main, totaling 45.3 miles. The predominant material used in the system, accounting for
approximately 54 percent of gravity piping, is polyvinyl chloride (PVC).
Approximately 72 percent of the gravity sewer’s installation year is unknown . Assumptions of
pipe ages based upon the material were made in an effort to determine the general age of the
collection system piping. AC was a popular material in sewer pipe construction between the
years of 1950 and 1970. A median installation year of 1960 was assumed for AC pipe where the
actual year is unknown. Both cast iron (CI) and vitrified clay (VC) were materials used primarily
before the 1950s. Ductile iron (DI) and high-density polyethylene (HDPE) use rises in popularity
in 1980 and is still used in present day, although largely for deep sewer pipe construction. A
median installation year of 2000 was assumed for DI and HDPE pipe where the actual year is
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unknown. Reinforced concrete pipe (RCP) is another older material where the use ranged from
1940 to 1960. A median installation year of 1950 was assumed for RCP pipe where the actual
year is unknown.
Table 2-1 summarizes the sewer system pipe by diameter, Table 2-2 summarizes the pipe by
material, and Table 2-3 summarizes the pipe by installation year. Figure 2-1 illustrates pipe
sizes and locations, and Figure 2-4 illustrates pipe material. Figure 2-5(a) illustrates the pipe
installation year with the known information. Figure 2-5(b) illustrates the assumed pipe
installation year based upon known information and pipe material, as described previously.
Table 2-1
Gravity Sewer Collection Piping Inventory – Diameter
Table 2-2
Gravity Sewer Collection Piping Inventory – Material
Diameter
(inches)
Total Length
(feet)
Total Length
(Miles)% of System
6 and smaller 100,808 19.09 25.4%
8 239,222 45.31 60.2%
10 20,188 3.82 5.1%
12 10,131 1.92 2.6%
14 1,963 0.37 0.5%
15 80 0.02 0.0%
16 3,462 0.66 0.9%
18 6,974 1.32 1.8%
22 1,376 0.26 0.3%
24 179 0.03 0.0%
30 6,471 1.23 1.6%
Unknown 6,222 1.18 1.6%
Total 397,077 75.20 100.0%
Material
Total Length
(feet)
Total Length
(Miles)% of System
AC 35,170 6.66 8.9%
CI 617 0.12 0.2%
DI 310 0.06 0.1%
HDPE 4,838 0.92 1.2%
PVC 214,161 40.56 53.9%
RCP 75,643 14.33 19.0%
VC 59,984 11.36 15.1%
Unknown 6,353 1.20 1.6%
Total 397,077 75.20 100.0%
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Table 2-3
Gravity Sewer Collection Piping Inventory – Installation Year
Force Mains
The City has approximately 2.2 miles of force mains. Table 2-4 summarizes the force mains by
diameter, Table 2-5 summarizes the force mains by material, and Table 2-6 summarizes the
force mains by installation year. Figure 2-1 illustrates the force main locations.
Approximately 41 percent of the force main installation years are unknown. Assumptions of the
pipe ages based upon the material were made in an effort to determine the general age of the
collection system piping.
Table 2-4
Force Main Inventory – Diameter
Installation
Year
Total Length
(feet)
Total Length
(Miles)% of System
Total Assumed
Length
(feet)
Total Assumed
Length
(Miles)% of System
Before 1950s ------60,502 11.46 15.2%
1950s ------74,267 14.07 18.7%
1960s 706 0.13 0.2%34,023 6.44 8.6%
1970s 1,940 0.37 0.5%1,940 0.37 0.5%
1980s 10,692 2.02 2.7%10,692 2.02 2.7%
1990s 30,163 5.71 7.6%30,163 5.71 7.6%
2000s 51,995 9.85 13.1%166,646 31.56 42.0%
2010s 14,082 2.67 3.5%14,082 2.67 3.5%
2020s 269 0.05 0.1%269 0.05 0.1%
Unknown 287,229 54.40 72.3%4,492 0.85 1.1%
Total 397,077 75.20 100.0%397,077 75.20 100.0%
Diameter
(inches)
Total Length
(feet)
Total Length
(Miles)% of System
4 1,718 0.33 15.1%
6 4,333 0.82 38.0%
10 2,706 0.51 23.8%
12 2,179 0.41 19.1%
16 381 0.07 3.3%
Unknown 78 0.01 0.7%
Total 11,395 2.16 100.0%
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Table 2-5
Force Main Inventory – Material
Table 2-6
Force Main Inventory – Installation Year
Lift Stations
The City currently owns, operates, and maintains seven wastewater lift stations. The
characteristics of the lift stations are summarized in Table 2-7, and a description of each lift
station follows.
Material
Total Length
(feet)
Total Length
(Miles)% of System
CI 6,259 1.19 54.9%
HDPE 381 0.07 3.3%
PVC 4,745 0.90 41.6%
Unknown 11 0.00 0.1%
Total 11,395 2.16 100.0%
Installation
Year
Total Length
(feet)
Total Length
(Miles)% of System
Total Assumed
Length
(feet)
Total Assumed
Length
(Miles)% of System
Before 1950s ------2,706 0.51 23.8%
1950s ------0 0.00 0.0%
1960s 2,179 0.41 19%2,179 0.41 19.1%
1970s 1,374 0.26 12%1,374 0.26 12.1%
1980s 0 0.00 0%0 0.00 0.0%
1990s 3,610 0.68 32%3,610 0.68 31.7%
2000s 0 0.00 0%1,515 0.29 13.3%
2010s 0 0.00 0%0 0.00 0.0%
2020s 0 0.00 0%0 0.00 0.0%
Unknown 4,232 0.80 37%11 0.00 0.1%
Total 11,395 2.16 100%11,395 2.16 100.0%
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Table 2-7
Lift Station Characteristics
Gaines Street Lift Station
The Gaines Street Lift Station was originally constructed
in 1967, and the pumps were upgraded in 2022. The
station is located at 201 Gaines Street and is equipped
with three 60 horsepower (hp) Flygt submersible pumps.
The station has a firm design capacity of 2,100 gallons
per minute (gpm) and is a conventional wet well/dry well
station. The Gaines Street Lift Station collects
wastewater from its sewer basin along with wastewater
from the Port, Monroe Street, and Port Hudson Lift
Stations in the southeastern portion of the system and
conveys it through the gravity collection system to the WWTF. Back-up power is provided by a
generator. The lift station is connected by radio communication to the City’s supervisory
control and data acquisition (SCADA) system.
Monroe Street Lift Station
The Monroe Street Lift Station, last upgraded in 2008,
pumps wastewater from the gravity collection system to
the Gaines Street Lift Station . The Monroe Street Lift
Station is equipped with three 15 hp Chicago dry pit
pumps that discharge into a 10-inch-diameter force
main. The lift station is connected by radio
communication to the City’s SCADA system. The lift
station has a hookup for a temporary generator, and
response time is less than 30 minutes to connect power.
The City is alerted when power is out by the SCADA
system, and this is the first lift station responded to.
Year Constructed
Force Main
Diameter
(inches)
No. of
Pumps Type Manufacturer
Horsepower
(hp)
TDH
(feet)
Design
Capacity
(gpm)
Design
Firm
Capacity
(gpm)
1,050
1,050
1,050
600
600
600
200
200
100
100
100
100
150
150
250
250
1001006.5FlygtSubmersible
Submersible Cornell 5 200
Submersible Peabody Barnes 1.5 150
Dry Pit Chicago 15 1,200
Point Hudson Lift Station 1975 - Constructed
1988 - Upgrade 4
Monroe Street Lift Station 1965 - Constructed
2008 - Upgrade 10
Port Lift Station 1967 6
2
61997Hamilton Heights Lift Station
1003Gorman-RuppSubmersible24
241985 - Constructed
2004 - UpgradeIsland Vista Lift Station
2505810FairBanks MorseSubmersible2
2
199631st Street Lift Station
PumpsLift Station
Lift Station Name
2,10010760FlygtSubmersible1967 - Constructed
2022 - UpgradeGaines Street Lift Station 36
3
Gaines Street Lift Station
Monroe Street Lift Station
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Port Lift Station
The Port Lift Station is located in the Port Townsend Boat
Haven Marina. Constructed in 1967, this submersible
station is equipped with two 5 hp Cornell pumps and has
a design firm pumping capacity of 200 gpm. All
wastewater from the Port Lift Station is pumped to the
Gaines Street Lift Station through a 6-inch-diameter force
main before being conveyed to the WWTF. The lift station
is connected by radio communication to the City’s SCADA
system. The lift station has a hookup for a temporary
generator, and staff generally have around 60 minutes to
connect power. The City is alerted when power is out by
the SCADA system, and this is the second lift station responded to.
31st Street Lift Station
The 31st Street Lift Station was constructed in 1996 and is located
at 1920 31st Street. This submersible lift station is equipped with
two 3 hp Gorman-Rupp submersible pumps that discharge into a
4-inch-diameter force main. The design capacity of the 31st Street
Lift Station is 100 gpm. Wastewater from the lift station mostly
consists of infiltration and inflow and is conveyed via gravity mains
to the City’s WWTF. The lift station is connected by radio to the
City’s SCADA system. The 31st Street Lift Station has a hookup for a
temporary generator. The City is alerted when power is out by the
SCADA system, and operators generally pump this out once or
twice in 24 hours.
Island Vista Lift Station
The Island Vista Lift Station is located at 112 Vista Boulevard, was
constructed in 1985, and was upgraded in 2004. This submersible
station collects wastewater and pumps it through the gravity
collection system to the WWTF. The lift station consists of two
Flygt submersible pumps that are each 6.5 hp with 100 gpm
capacity. The lift station is connected by radio to the City’s SCADA
system. This lift station has a hookup for a temporary generator.
The City is alerted when power is out by the SCADA system, and
operators generally pump this out once or twice in 24 hours.
Port Lift Station
31st Street Lift Station
Island Vista Lift Station
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Point Hudson Lift Station
Originally constructed in 1967, the Point Hudson Lift Station was
most recently upgraded in 1988. The Point Hudson Lift Station
collects wastewater that is conveyed to the Monroe Street Lift
Station before flowing to the Gaines Street Lift Station and
ultimately, the City’s WWTF. This submersible lift station has
two 1.5 hp Peabody Barnes pumps that have a capacity of
150 gpm each. This lift station is not connected to the City’s
SCADA system. The Point Hudson Lift Station has a hookup for a
temporary generator. The City is alerted when power is out by
the SCADA system, and operators generally pump this out once
or twice in 24 hours.
Hamilton Heights Lift Station
The Hamilton Heights Lift Station is located near
2500 Howard Street and was constructed in 1997. This
submersible lift station consists of two 10 hp FairBanks
Morse pumps and has a design capacity of 250 gpm.
Wastewater from this lift station is conveyed through a
6-inch force main before flowing by gravity main to the
City’s WWTF. The lift station is connected by radio to the
City’s SCADA system. The Hamilton Heights Lift Station
has a permanent backup generator.
Low Pressure Sewer Systems
The City has permitted a small number of low pressure sewers over the last 20 years. Low
pressure sewers consist of a private single pump lift station located at a residential structure
with a small force main that ultimately connects to gravity sewer. Often, multiple private
pumps will discharge into a shared private force main as illustrated in the schematic that
follows.
Point Hudson Lift Station
Hamilton Heights Lift Station
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Low Pressure Sewer System Schematic. Image credit: Environmental One website.
Historically, the City has only allowed low pressure sewers if they were entirely privately
maintained, including the force main. The City generally discouraged this approach to sewer
service as technology was still under scrutiny and private ownership of pump stations was
considered problematic due to pump failures and the inability to quickly fix the problem. Failure
of private pumps also leads to sewer overflows. Many cities have not taken on ownership of
these private pumps due to the massive impact on city maintenance costs given the pumps
were considered unreliable.
The technology and reliability of low pressure sewer pump systems has improved considerably
and now failures of the pump systems are rare. Many municipalities are now embracing the
application of low pressure sewers in areas that are hard to serve due to undulating topography
where gravity sewer is not feasible.
This GSP suggests there are areas within the City that would benefit greatly from the
installation of low pressure sewer pump systems. Recommended standards for low pressure
sewers are included in Chapter 5.
Private grinder sewer
pump system Private lateral
Shared force
main
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Wastewater Treatment and Disposal Facilities
Existing System
The City’s WWTF is located just west of Fort Worden in
the North Beach neighborhood. The WWTF was
originally constructed in 1967 and provided only primary
treatment and disinfection using chlorine gas. The facility
was expanded in 1993 to provide secondary treatment.
Raw wastewater enters the WWTF from two gravity
sewers, and an influent pump station lifts the
wastewater to the headworks. Within the headworks, a
bar screen removes rags and floating debris, and then a
grit classifier settles out the sand and heavy materials.
The flow rate of the screened and de-gritted influent is
measured in a Parshall flume and the liquid then flows to
the oxidation ditches. In the oxidation ditches, surface
mixers stir air into the liquid, promoting the gro wth of
microbiological cultures that consume the biochemical
oxygen demand (BOD) in the mixture and form a solution
known as mixed liquor. The mixed liquor flows to the
secondary clarifier, where the biological solids settle out.
The clarified effluent flows to the chlorination basins,
where it is chlorinated using liquid sodium hypochlorite.
Effluent is retained in the chlorine contact chambers for
at least 20 minutes to ensure complete disinfection.
The biological solids (liquid sludge) produced during secondary clarification are pumped to the
small aerobic digesters for a short stabilization period. The liquid sludge is then pumped to the
control building, where it is blended with polymer and dewatered using a belt filter press.
Treated Wastewater Discharge and Solids Handling
Wastewater from the City’s sewer system is processed at the WWTF, resulting in treated water
and digested sludge. The treated effluent is dechlorinated using liquid sodium bisulfite and
discharged to the Strait of Juan de Fuca via a 2,300-foot-long, 18-inch-diameter pipeline and
outfall ending 700 feet offshore.
The dewatered sludge is loaded into a truck and hauled to the City’s Compost Facility at the
Jefferson County Waste Management Facility site. Sludge from the WWTF is composted at the
facility in combination with dewatered septage, yard waste, and other wood wastes. Liquids
from the process and a portion of the County’s septage hauling are treated in a sequencing
batch reactor and constructed wetlands and discharged to infiltration basins for additional
treatment and ultimate disposal.
WWTF Oxidation Ditches
WWTF Chlorine Pumping Room
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DISCHARGE AND DISPOSAL REGULATIONS AND PERMITS
WWTF NPDES Permit and Regulations
Wastewater flow and loading into the City’s WWTF and treated plant effluent water discharged
to the Strait of Juan de Fuca in Puget Sound are regulated through the City’s National Pollutant
Discharge Elimination System (NPDES) Permit.
The federal Clean Water Act (CWA, 1972, and later modifications, 1977, 1981, and 1987)
established water quality goals for the navigable (surface) waters of the United States: “The
objective of the CWA is the restoration and maintenance of the chemical, physical, and
biological integrity of the country’s water.” The CWA grants individual authority to each state to
define the water quality standards (within the limits set by the water quality goals) within its
jurisdiction and enforce them. Water quality standards for surface waters in Washington State
have been established (Chapter 173-201A WAC) and are enforced by Ecology (Chapter 90.48
Revised Code of Washington (RCW)). The purpose of the water quality standards is to provide
“public health and public enjoyment of the waters and the propagation and protection of fish,
shellfish, and wildlife.” Each surface water in the state is identified as fresh water or marine
water and designated for one or more uses, which then determines the specific water quality
standards that apply to that water.
The state also has established a permit program for implementation of the NPDES Permit
Program created by the CWA. The program requires a discharge permit for any point source,
such as a domestic wastewater treatment plant, and discharge of pollutants to surface waters
of the state for the purpose of maintaining the water quality standards. Each pe rmit is renewed
on roughly a 5-year cycle. The permit and accompanying fact sheet include information on
discharge limits, monitoring schedules, and general and special conditions that apply to the
applicable point source.
The City’s current NPDES Permit (Permit No. WA0037052) has an effective date of
December 1, 2015, and expired on November 30, 2020. The WWTF continues to operate under
this permit as Ecology is currently reviewing and has not issued a revised NPDES permit since
the expiration date. Copies of the permit and accompanying fact sheet are included as
Appendix C.
Facility Design Criteria
The permitted facility flow and loading design criteria for the WWTF are included in Table 2-8.
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Table 2-8
WWTF Permitted Flow and Loading Design Criteria
Effluent Limits
Treated plant effluent water is discharged to the Strait of Juan de Fuca through a piped outfall,
which is designated as Outfall No. 001 in the NPDES Permit. The effluent limits for Outfall
No. 001 are summarized in Table 2-9.
Table 2-9
NPDES Permit Effluent Limits
Future City NPDES Permit Effluent Limits (Outfall No. 001) Changes
Ecology can change water quality standards or NPDES Permit effluent limits (the latter for the
purpose of maintaining water quality standards). Know n future changes to water quality
standards and NPDES Permit effluent limits that are applicable to Outfall No. 001 at the WWTF
are summarized in this section.
Bacterial Indicator Effluent Limits
The receiving water of the Strait of Juan de Fuca at Outfal l No. 001 is designated for Primary
Contact Recreational Use (WAC 173-201A-612, Table 612). To protect water contact recreation
in marine water, such as the receiving water, bacterial indicator criteria (standards) are defined
(WAC 173-201A-210(3)(b)). Ecology is reviewing adding an E. coli standard in future permits.
Parameter Design Quantity
Maximum Month Design Flow (MMDF)2.05 MGD
Annual Average Flow 1.44 MGD
BOD5 Influent Loading for Maximum Month 3,754 ppd
TSS Influent Loading for Maximum Month 4,568 ppd
Design Population 12,000
MGD = million gallons per day
ppd = pounds per day
Parameter Average Monthly Average Weekly
Biochemical Oxygen Demand (5-Day) (BOD5)
30 mg/L
513 ppd
85% removal of influent BOD5
45 mg/L
769 ppd
Total Suspended Solids (TSS)
30 mg/L
513 ppd
85% removal of influent TSS
45 mg/L
769 ppd
Total Residual Chlorine 0.5 mg/L 0.75 mg/L
Parameter Minimum Maximum
pH 6.0 standard units 9.0 standard units
Parameter Monthly Geometric Mean Weekly Geometric Mean
Fecal Coliform Bacteria 200/100 mL 400/100 mL
mg/L = milligrams per liter
mL = milliliters
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The E. coli and fecal coliform bacterial indicator criteria are both defined in the current version
of WAC 173-201A-210(3)(b).
The City’s NPDES Permit has a fecal coliform bacteria effluent limit for Outfall No. 001. An E. coli
bacteria effluent limit for Outfall No. 001 will be evaluated and further monitoring will be
required when the permit is renewed. As Ecology continues to review, the current fecal
coliform bacteria effluent limit will remain effective.
Other Regulations and Required Permits
WWTF Puget Sound Nutrient General Permit
Section 303(d) of the CWA establishes a process to identify and clean up surface waters that do
not meet the applicable water quality standards. Every few years, Ecology performs a water
quality assessment using collected data to determine whether water quality of the surface
waters meets the standards. Based on the assessment, each surface water is placed into one of
five categories that describes the status of the water quality and ranges from meeting the
standards (Category 1) to impaired (i.e. polluted) and requiring a water improvement project
(Category 5). Surface waters placed into Category 5 are listed on the state’s 303(d) list of
polluted waters, which is named after the referenced section of the CWA.
At certain times of the year, dissolved oxygen levels in a large number of locations throughout
Puget Sound do not meet the applicable water quality standards, and in many other locations
show evidence of not meeting the standards in the future. The surface waters within Puget
Sound that are not meeting the dissolved oxygen standards are listed in the state’s 303(d) list.
Ecology initiated the Puget Sound Nutrient Reduction Project (Project) in the spring of 2017 to
address the problem of human sources of nutrients contributing to the low and decreasing
dissolved oxygen levels throughout Puget Sound. As a result of modeling, Ecology believes
discharges of nutrients to Puget Sound from domestic wastewater treatment plants are
significantly contributing to the problem. The goal of the Project is to develop a nutrient source
reduction strategy, which includes reducing nutrient levels discharged from domestic
wastewater treatment plants.
Ecology has been utilizing a model of Puget Sound to understand the problem and simulate
potential improvements. Ecology has identified nitrogen as the limiting nutrient, with inorganic
nitrogen, consisting of nitrate-nitrite and ammonia, as the “biologically available” form. Ecology
is performing additional modeling for optimization scenarios; however, results from completed
modeling are being used to determine effluent nitrogen permit limits for domestic wastewater
treatment plants with outfalls to Puget Sound (identified as marine sources), which includes the
City’s WWTF. Individual NPDES permits for the same treatment plants will continue
independently of, but in conjunction with, the general permit and may be modified as
necessary to include facility-specific nutrient-related requirements.
In January 2021, Ecology released a preliminary draft of the Puget Sound Nutrient General
Permit (PSNGP) for public comment. The public comment period ended on March 15, 2021, and
Ecology has proceeded with developing a formal version, which became effective January 1,
2022, and expires December 31, 2026. Copies of the final PSNGP (Permit No. WAG994538) and
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accompanying fact sheet are included as Appendix D. The following descriptions summarize the
final PSNGP, including anticipated permit limits specific to the City’s WWTF.
Notice of Intent
The City has filed a Notice of Intent for coverage under the PSNGP and will submit Discharge
Monitoring Reports (DMRs) as required by the permit and as discussed as follows.
Nitrogen Optimization Requirements
The City must submit an annual Nitrogen Optimization Plan (NOP) to Ecology no later than
March 31, 2026, as defined in the PSNGP. Optimization refers to short-term actions (low-cost
controls and process changes) focused on improving existing performance. Optimization
processes do not include large scale capital investments. The City must begin optimization
immediately upon coverage under the PSNGP.
The NOP must include the following components:
1. Treatment Process Performance Assessment
Assess the nitrogen removal potential of the current treatment process and have the
ability to evaluate optimization strategies prior to implementation.
a. Evaluation. Develop a treatment process assessment method for the purposes of
evaluating optimization approaches during the permit term. This will include an
evaluation of current (pre-optimization) process performance to determine the
empirical Total Inorganic Nitrogen (TIN) removal rate for the WWTF. The assessment
must include an evaluation of possible optimization strategies at the WWTF prior to
and after implementation. Determine the optimization goal for the WWTF and
develop a list of optimization strategies capable of achieving the optimization goal
for the WWTF. Update this list as necessary to continuously maintain a selection of
strategies for achieving each optimization goal identified. Any optimization strategy
may be excluded from the initial selection if it is found to exceed a reasonable
implementation cost or timeframe. Documentation must be provided that includes
an explanation of the rationale and financial criteria used for the exclusion
determination.
b. Initial Selection. Identify the optimization strategy selected for implementation .
Document the expected percentage of TIN removal (or the expected reduction in
effluent load) for the optimization strategy prior to implementation.
2. Optimization Implementation
The City must document implementation of the selected optimization strategy, which
includes the following:
a. Strategy Implementation. Describe how the selected strategy was implemented
during the reporting period, initial implementation costs, length of time to
implement (including start date), anticipated and unanticipated challenges, and
impacts to the overall treatment performance due to optimization process changes.
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b. Load Evaluation. The City must review effluent data collected during the reporting
period to determine whether TIN loads are increasing. This includes using all
accredited monitoring data to determine the WWTF’s annual average TIN
concentration and load for each year during the reporting period. The City also must
determine the WWTF’s TIN removal rate at the end of each year and compare it
with the pre-optimization rate previously identified.
c. Strategy Assessment. The City must quantify the results of the implemented strategy
and compare them to the expected percentage of TIN removal previously identifie d.
If the TIN loading increased, apply adaptive management, and re-evaluate the
optimization strategies and the resulting performance to identify the reason. From
this, select a new optimization strategy or revise the implementation for better
performance. Document any updates to the implementation schedule and overall
plan.
3. Influent Nitrogen Reduction Measures/Source Control
The City must investigate opportunities to reduce influent TIN loads from septage
handling practices, commercial, dense residential, and industrial sources and submit
documentation with the Annual Report. This includes the following:
a. Review non-residential sources of nitrogen and identify any possible pretreatment
opportunities.
b. Identify strategies for reducing TIN from new multi-family/dense residential
developments and commercial buildings.
AKART Analysis
Under the PSNGP, all permittees classified as Small Loaders must prepare and submit an
approvable all known, available, and reasonable treatment (AKART) analysis to Ecology for the
purposes of evaluating reasonable treatment alternatives capable of reducing TIN. Permittees
that maintain an annual TIN average of less than 10 milligrams per liter (mg/L) and do not
document an increase in load through their DMRs are excluded from this requirement and do
not have to submit this analysis.
Monitoring Requirements
The PSNGP will create additional monitoring requirements for the City. These requirements do
not replace any requirements stipulated in the City’s NPDES Permit. The City will need to
comply with both permits separately. Recorded monitoring data should be submit ted monthly
on the electronic DMR form provided by Ecology within the Water Quality Permitting Portal.
The City may use the monitoring locations identified in the N PDES Permit to collect samples for
the PSNGP, but must still prepare two separate monthly DMR submittals (one for each permit).
Samples must be representative of the flow and characteristics of the discharge , and sampling
is not required outside of normal working hours or during unsafe conditions. For each sample
taken, the City must record the sample date and time, location, method of sampling, and
individual who performed the sampling. The City must use appropriate flow measurement and
methods consistent with accepted scientific practices, including proper installation, calibration,
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and maintenance of all measurement devices. A summary of the anticipated monitoring
requirements under the PSNGP and a comparison to the City’s NPDES Permit can be found in
Tables 2-10 and 2-11.
Table 2-10
Comparison of City NPDES Permit and PSNGP Monitoring Requirements for WWTF Influent
Table 2-11
Comparison of City NPDES Permit and PSNGP Monitoring Requirements for WWTF Effluent
The City must submit monthly monitoring data using Ecology’s WQWebDMR progra m by the
15th day of the following month. Any pollutant monitoring data collected more frequently than
the permit stipulates must be used in calculations and submitted in the DMR.
After 12 months of monitoring, the City may request a reduction in sampling frequency fro m
Ecology if it can demonstrate that the distribution of concentrations can be accurately
represented with a lower sampling frequency.
Parameter Units and
Specification
Minimum Sampling
Frequency (NPDES)
Minimum Sampling
Frequency (PSNGP)Sample Type
Flow MGD Continuous -Metered/Recorded
BOD5 mg/L 1/week -24-Hour Composite
BOD5 ppd 1/week -Calculated
TSS mg/L 1/week -24-Hour Composite
TSS ppd 1/week -Calculated
CBOD5 mg/L -2/month 24-Hour Composite
Total Ammonia mg/L as N -2/month 24-Hour Composite
Nitrate plus Nitrite mg/L as N -1/month 24-Hour Composite
Total Kjeldahl Nitrogen mg/L as N -1/month 24-Hour Composite
Parameter Units and
Specification
Minimum Sampling
Frequency (NPDES)
Minimum Sampling
Frequency (PSNGP)Sample Type
Flow MGD -2/month Metered/Recorded
BOD5 mg/L 1/week -24-Hour Composite
BOD5 ppd 1/week -Calculated
BOD5 % removal 1/week -Calculated
TSS mg/L 1/week -24-Hour Composite
TSS ppd 1/week -Calculated
TSS % removal 1/week -Calculated
Chlorine (Total Residual)mg/L 1/week -Grab
Fecal Coliform #/100 ml 1/week -Grab
pH Standard Units 1/day -Grab
CBOD5 mg/L -2/month 24-Hour Composite
Total Organic Carbon mg/L -1/quarter 24-Hour Composite
Total Ammonia mg/L as N -2/month 24-Hour Composite
Nitrate plus Nitrite mg/L as N -2/month 24-Hour Composite
Total Kjeldahl Nitrogen mg/L as N -1/month 24-Hour Composite
Total Inorganic Nitrogen (TIN)mg/L as N -2/month Calculated
TIN ppd -2/month Calculated
Average Monthly TIN lbs -1/month Calculated
Annual TIN, year to date lbs -1/month Calculated
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Additional Requirements
The City must retain records of monitoring information or documentation pertaining to permit
requirements for a minimum of 5 years following termination of permit coverage. If the City is
unable to comply with the conditions of the permit, it must notify Ecology within 24 hours and
submit a written report to Ecology via the WQWebPortal within 5 days describing the
noncompliance event and duration, and how steps will be taken to correct it. The City must
keep the following documentation onsite or within reasonable access to the site: Permit
Coverage Letter, PSNGP, DMRs, and attachments to the NOP.
Compost Facility Regulations for Biosolids
Chapter 173-308 WAC is the basis for the state-wide biosolids management program. Facilities
that are subject to the permit program apply for coverage under the existing state -wide general
permit. The state biosolids program regulates facilities that produce, treat, or land apply
sewage sludge or biosolids for beneficial use. The City’s Compost Facility is covered under the
general permit to produce Class A biosolids as defined in the federal 40 CFR 503 regulations.
Biosolids quality is measured using three parameters: pathogen reduction, vector attraction
reduction, and pollutant concentration. Pathogen reduction uses accepted treatment processes
or requires measurement of pathogen concentration to determine compliance. To receive
classification as Class A, biosolids must go through a rigorous process called a Process to
Further Reduce Pathogens. This reduces pathogens below detectable limits. Operators must
test all Class A biosolids for pathogens and indicator organisms.
Vector attraction is related to odor control and can be thought of as the appeal that the
biosolids present to organisms (e.g., flies) that may transmit pathogens, if pathogens were
present in the biosolids. Reduction of vector attraction can be achieved through lime
stabilization, reducing volatile solids content, or physical mixing processes.
Pollutant concentration refers to the pollutant limits established in WAC 173-308-160. This sets
a ceiling concentration limit for each pollutant, meaning the maximum allowable concentration
in biosolids. It also lists the pollutant concentration limit, which is lower than the ceiling limit.
Biosolids with pollutants above the pollutant concentration limit are subject to cumulative
loading limits on application sites.
The City’s existing solids handling system is discussed in Chapter 7. Proposed solids handling
improvements are discussed in Chapter 8.
Compost Facility State Waste Discharge Permit
The City’s Compost Facility contains a Sequencing Batch Reactor (SBR) that treats liquids from
the composting process and also a portion of the County’s septage hauling and discharges to
constructed wetlands and then infiltration basins for further treatment and disposal. The
Compost Facility’s WWTF is covered under the State Waste Discharge Permit (SWDP), which
regulates the flow and loading of the SBR and adjacent wetlands. The City’s current SWDP
(Permit No. ST 6127) has an effective date of July 1, 2019, and expires on June 30, 2024. Copies
of the permit and accompanying fact sheet are included as Appendix E.
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Facility Design Criteria
The permitted flow and loading design criteria for the Compost Facility are included in
Table 2-12.
Table 2-12
Compost Facility Flow and Loading Design Criteria
Effluent Limits
SBR effluent water is discharged to infiltration basins, designated as wetlands in the SWDP,
west of the Compost Facility. The effluent limits for the SBR and wetland influent and effluent
are summarized in Tables 2-13 and 2-14.
Table 2-13
State Waste Discharge Permit SBR Effluent Limits
Table 2-14
State Waste Discharge Permit Wetland Effluent Limits
Parameter Design Quantity
Maximum Month Design Flow (MMDF)4,000 gpd
Daly Maximum Flow 6,200 gpd
gpd = gallons per day
Parameter Average Monthly Average Weekly
BOD5
30 mg/L
1 ppd
85% removal of influent BOD5
45 mg/L
1.5 ppd
TSS
30 mg/L
1 ppd
85% removal of influent TSS
45 mg/L
1.5 ppd
Parameter Minimum Maximum
pH 6.0 standard units 9.0 standard units
Parameter Monthly Geometric Mean 7-Day Geometric
Mean
Fecal Coliform 200 col/100 mL 400 col/10 mL
Parameter Average Monthly Average Weekly
Total Residual Chlorine 0.5 mg/L 0.75 mg/L
Parameter Average Monthly Average Weekly
Nitrate 10 mg/L as N -
Effluent Limits: Wetland Influent
Effluent Limits: Wetland Effluent
CITY OF PORT TOWNSEND GENERAL SEWER PLAN SEWER SYSTEM DESCRIPTION AND DISCHARGE REGULATIONS
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ADJACENT SEWER SYSTEMS
There are no municipal sewer service systems adjacent to the City. The closest wastewater
treatment plant to the City is the Port Townsend Paper Corporation just south of the City limits .
The surrounding areas of unincorporated Jefferson County do not have sewer service, and
wastewater is managed with on-site septic systems, community drain fields, or alternative
sewage treatment technologies. However, the County is in the process of constructing a sewer
plant and collection system in Hadlock that will allow for conversion of existing septic systems
to public sewer and growth of housing and businesses within the Hadlock UGA.
Figure 2-6 shows the wastewater treatment facilities within 20 miles of the City.
CITY OF PORT TOWNSEND AND ADJACENT WATER SYSTEMS
City of Port Townsend
The City’s existing retail water service area, which covers an area of approximately 11.2 square
miles, is shown on Figure 2-7 The existing retail service area includes the current City limits and
adjacent lands to the west and south of the City limits.
This section provides a brief description of the existing water system and the current operation
of the facilities. The water service area, facilities, and supply sources are shown in Figure 2-7.
Water is supplied to the City’s system by the Big Quilcene and Little Quilcene Rivers.
The City's wastewater facilities are all separated from major drinking water facilities for the City
and adjacent drinking water purveyors. As a result of this separation, the City's wastewater
facilities are unlikely to conflict with or impact the drinking water facilities or supplies for the
City or neighboring purveyors.
Pressure Zones
The City divides the water system into two different pressure zones, the “High Zone” and the
“Low Zone.” Prior to 1998, the City was served from a single pressure zone (the Low Zone).
Service pressures ranged from above 130 pounds per square inch (psi) near the shoreline of
Puget Sound to less than 20 psi at the higher elevations within the service area. To increase
system pressures, the City installed a new, taller storage tank, which provides higher service
pressures in areas of the City with higher elevations, creating the initial phase of the High Zone.
The High Zone serves areas generally above 210 feet of elevation, resulting in a typical High
Zone pressure range of 35 psi to 70 psi (although there are localized areas over 70 psi). The City
expanded the extent of the High Zone to adjacent northwest areas of similarly higher elevation
in 2004 to ensure service pressures in that area were maintained above the Washington State
Department of Health minimum criterion of 30 psi. The revised Low Zone pressure range is
typically from about 50 psi to above 130 psi, but there are localized areas under 50 psi.
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Supply Facilities
Introduction
The City water system is supplied by surface water from the Big Quilcene and Little Quilcene
Rivers, which are located approximately 30 and 20 miles south of the City, respectively. The
diversions at the Little Quilcene and Big Quilcene Rivers provide flow to Lords Lake and to City
Lake, which are both man-made impoundments. The headwaters of each river originate within
the Olympic National Forest and Olympic National Park. The U.S. Forest Service manages most
of the municipal watershed and the City has a good working relationship with them. The Big
Quilcene River is the primary water supply for the City. Water from the Little Quilcene River
diversion is used to fill Lords Lake, which has a capacity of approximately 500 million gallons
(MG). Lords Lake also can be filled from the Big Quilcene Diversion. The City’s surface water
supplies are high quality and generally very low in turbidity. When the Big and Little Quilcene
Rivers experience high turbidity events, the City and the Port Townsend Paper Corporation use
water stored in Lords Lake or City Lake. The entire system operates by gravity from both of the
diversions, to Lords Lake, City Lake, and the City. City Lake functions as a raw water equalizing
reservoir with approximately 140 MG of storage.
Water Treatment
Prior to treatment, water from City Lake flows through two sets of mesh screen, which prevents
objects larger than 3/32 inch from entering the Olympic Gravity Water System pipeline below
City Lake. The new water treatment facility (WTF), completed in 2017, is located adjacent to the
City’s existing water storage tanks. The WTF has the following features:
• Raw water flow and pressure control valves.
• Mechanical micro-screens for removing algae and larger-sized sediment.
• Pressure ultrafiltration membranes for the removal of microbial pathogens (Giardia and
cryptosporidium), sediment, and semi-colloidal particles.
• Sodium hypochlorite feed to provide primary disinfection and a chlorine residual in the
finished water throughout the distribution system.
• Potassium permanganate injection system for treatment of algal toxins in the event
toxins are detected in the raw water supply.
• Automated control system.
• Standby power generator.
Pump Station Facilities
The City’s water system has two booster pump station (BPS) facilities. The Morgan Hill BPS,
constructed in 2004, has two domestic flow pumps (one service, one standby), three high flow
pumps (two service, one standby), and emergency power (Table 2-15). The BPS serves a closed
distribution system with 2,000 gallons of storage via a hydro -pneumatic tank on top of the hill.
The second BPS is located at the WTF and pumps water into the High Zone and 1 MG Standpipe
reservoir.
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Table 2-15
Booster Pump Station Facilities Summary
Storage Facilities
The City’s water system has two facilities that provide storage to the water system (Table 2-16).
A 37-foot-tall, 160-foot-diameter 5 MG prestressed concrete reservoir serves the City’s low
elevation zone, and an 84-foot-tall, 47-foot-diameter 1 MG steel standpipe serves the City’s
high elevation zone. Both reservoirs have baffles to increase the contact time (CT) in the
reservoir in order to meet CT requirements.
Table 2-16
Storage Facilities Summary
Distribution and Transmission System
The City’s water system contains approximately 110 miles of water main ranging in size from
2 inches to 36 inches. Most of the water main (approximately 33 percent) within the system is
6 inches in diameter or less. Approximately 56 percent of the distribution system is constructed
of AC pipe. The majority of the remainder of the piping system is constructed of PVC pipe. The
City has complied with water quality testing requirements for asbestos in the water system,
demonstrating that concentrations are below state and federal standards.
Water System Interties
Water system interties are physical connections between two adjacent water systems. Interties
normally are separated by a closed isolation valve or control valve. Emergency supply interties
provide water from one system to another during emergency situations only. An emergency
situation may occur when a water system loses its main source of supply or a major
transmission main, or during firefighting situations, and is unable to provide a sufficient
quantity of water to its customers. Normal supply interties provide water from one system to
another during non-emergency situations and are typically supplying water at all times.
The City does not have any interties with any adjacent water systems.
Facility Year Constructed Description/Size Capacity
Morgan Hill BPS 2004 Domestic Flow Pumps
High Flow Pumps
(2) 100 gpm
(3) 550 gpm
WTF BPS 2017 Domestic Flow Pumps
Low Flow Pump1
(2) 2,100 gpm
(1) 450 gpm
1. Used to boost Low Zone pressure to serve the High Zone when the 1 MG Standpipe is offline for service.
Facility Year Constructed Description/Size Capacity Construction Materials
5 MG Reservoir 2017 37 Feet Tall
160 Feet Diameter 5 MG Concrete
1 MG Standpipe 1994 84 Feet Tall
47 Feet Diameter 1 MG Steel
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Adjacent Water Systems
The City’s water service area is shown in Figure 2-7. Three water systems share a boundary with
the City: Deaner Line, Jamie Kozelisky, and Quimper (Jefferson County Public Utility District
(PUD) No.1). Other purveyors located on the Quimper Peninsula, but not sharing a boundary
with the City, include Jefferson County PUD No. 1 Vandecar, Cape George, and Jefferson County
PUD No. 1 Valiani.
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Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
Strait of Juan De Fuca
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200'
20
0
'
200'
200'
200
'
200'
2
0
0
'
1
0
0
'
200'
200'
2
0
0
'
20
0
'
1
0
0
'
200
'
2
0
0
'
100'
200
'
20
0
'
200'
100'
2
0
0
'
200
'
2
0
0
'
N
DRAWING IS FULL SCALE
WHEN BAR MEASURES 1”
0 2,0001,000
Feet
1 inch : 2,000 Feet
Legend
City Limits/Urban Growth Area Boundary
100' Contour
20' Contour
Sewer Infrastructure
³³WWTF Wastewater Treatment Facility
"L Lift Station
Force Main
Outfall
Gravity Main
Sewer Drainage Basin
Admiralty Avenue
Discovery Road
F Street
Gaines Street
Golf Course
Hastings Avenue
Monroe Street
North Bend
Port
San Juan Avenue
Seaview/Howard Street
Sims Way
Southwest
West
\\
C
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2
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P
l
a
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Ge
n
e
r
a
l
S
e
w
e
r
P
l
a
n
Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
100'
Strait of Juan De Fuca
Port Townsend Bay
Admiralty Inlet
Kah Tai
Lagoon
Chinese
Gardens
Hamilton Heights
Lift Station
31st Street
Lift Station
Point Hudson
Lift Station
Monroe Street
Lift Station
Gaines Street
Lift Station
Port
Lift Station
Island Vista
Lift Station
Outfall
Port
Esri, HERE,
Garmin,
USGS, EPA
"L
"L
"L
"L
"L
"L
"L
³³WWTF
Seaview/Howard
Street
Sims Way
West
Hastings
Avenue
Admiralty Avenue
Monroe
Street
San Juan Avenue
Southwest
Discovery
Road
Golf
Course
Gaines
Street
F Street
North Bend
SIMS WAY
HASTINGS AVE
F ST
39TH ST S ST
COO
K
A
V
E
U ST
W ST
20TH ST
RA
I
N
I
E
R
S
T
HI
L
L
S
T
P ST
30TH ST
TH
O
M
A
S
S
T
S
J
A
C
O
B
M
I
L
L
E
R
R
D
MILL RD
BLAIN
E
S
T
29TH ST
V ST
T ST
6TH ST
5TH ST
CH
E
R
R
Y
S
T
43RD ST
49TH ST
1S
T
S
T
.
SA
N
J
U
A
N
A
V
E
25TH ST
7TH ST
JA
C
K
M
A
N
S
T
3RD ST
HE
N
D
R
I
C
K
S
S
T
BE
L
L
S
T
O ST
22ND ST
2ND ST
IV
Y
S
T
SP
R
I
N
G
S
T
P
E
A
R
Y
A
V
E
ED
D
Y
S
T
ARCADIA W
57TH ST
N
J
A
C
O
B
M
I
L
L
E
R
R
D
27TH ST
JENSEN ST
W
A
L
K
E
R
S
T
HA
R
B
O
R
D
E
F
E
N
S
E
W
A
Y
36TH ST
S
8
T
H
S
T
HI
D
D
E
N
T
R
A
I
L
S
R
D
MID
D
L
E
P
O
I
N
T
R
D
K
E
A
R
N
E
Y
S
T
15TH ST
AL
B
A
T
R
O
S
S
S
T
35TH ST
38TH ST
37TH ST
GI
B
B
S
S
T
BA
K
E
R
S
T
JUAN DE FUCA RD
DENNY AVE
BOREN AVE
PERSHIN
G
A
V
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C
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P
E
G
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O
R
G
E
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RAINSHADOW RD
KAN
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ALEXANDER
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S
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P
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T
P
A
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A
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35TH ST
SA
N
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A
N
A
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HI
L
L
S
T
4
9
T
H
S
T
20TH ST
3RD ST
25TH ST
6TH ST
3RD ST
IV
Y
S
T
N
DRAWING IS FULL SCALE
WHEN BAR MEASURES 1”
0 2,0001,000
Feet
1 inch : 2,000 Feet
Legend
City Limits/Urban Growth Area Boundary
Sewer Infrastructure
³³WWTF Wastewater Treatment Facility
"L Lift Station
Force Main
Outfall
Gravity Main by Material
Vitrified Clay
Cast Iron
Asbestos Cement
Ductile Iron
HDPE
Reinforced Concrete Pipe
PVC
Unknown
Sewer Drainage Basin
Admiralty Avenue
Discovery Road
F Street
Gaines Street
Golf Course
Hastings Avenue
Monroe Street
North Bend
Port
San Juan Avenue
Seaview/Howard Street
Sims Way
Southwest
West
\\
C
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P
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2
.
C
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2
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r
a
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S
e
w
e
r
P
l
a
n
Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
Strait of Juan De Fuca
Port Townsend Bay
Admiralty Inlet
Kah Tai
Lagoon
Chinese
Gardens
Hamilton Heights
Lift Station
31st Street
Lift Station
Point Hudson
Lift Station
Monroe Street
Lift Station
Gaines Street
Lift Station
Port
Lift Station
Island Vista
Lift Station
Outfall
Port
Esri, HERE,
"L
"L
"L
"L
"L
"L
"L
"L
³³WWTF
Seaview/Howard
Street
Sims Way
West
Hastings
Avenue
Admiralty Avenue
Monroe
Street
San Juan Avenue
Southwest
Discovery
Road
Golf
Course
Gaines
Street
F Street
North Bend
SIMS WAY
HASTINGS AVE
F ST
39TH ST S ST
COO
K
A
V
E
W ST
20TH ST
RA
I
N
I
E
R
S
T
HI
L
L
S
T
P ST
30TH ST
TH
O
M
A
S
S
T
S
J
A
C
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B
M
I
L
L
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R
R
D
MILL RD
BLAIN
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S
T
29TH ST
6TH ST
5TH ST
CH
E
R
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S
T
43RD ST
49TH ST
1S
T
S
T
.
SA
N
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25TH ST
7TH ST
JA
C
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22ND ST
2ND ST
IV
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SP
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S
T
PE
A
R
Y
A
V
E
ARCADIA W
N
J
A
C
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B
M
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L
L
E
R
R
D
27TH ST
JENSEN ST
W
A
L
K
E
R
S
T
HA
R
B
O
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D
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F
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N
S
E
W
A
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36TH ST
S
8
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B
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38TH ST
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B
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BA
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DENNY AVE
BOREN AVE
PERSHING
A
V
E
C
A
P
E
G
E
O
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G
E
R
D
RAINSHADOW RD
KAN
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D
R
ALEXANDER'S L
P
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T
P
A
R
K
A
V
E
35TH ST
IV
Y
S
T
49
T
H
S
T
6TH ST
25TH ST
3RD ST
N
DRAWING IS FULL SCALE
WHEN BAR MEASURES 1”
0 2,0001,000
Feet
1 inch : 2,000 Feet
Legend
City Limits/Urban Growth Area Boundary
Sewer Infrastructure
³³WWTF Wastewater Treatment Facility
"L Lift Station
Force Main
Outfall
Gravity Main by Installation Year
1960 to 1969
1970 to 1979
1980 to 1989
1990 to 1999
2000 to 2009
2010 to 2019
2020 to Present Day
Unknown
Sewer Drainage Basin
Admiralty Avenue
Discovery Road
F Street
Gaines Street
Golf Course
Hastings Avenue
Monroe Street
North Bend
Port
San Juan Avenue
Seaview/Howard Street
Sims Way
Southwest
West
J:
\
D
A
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\
T
W
N
S
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\
2
1
-
0
2
2
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2
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:
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a
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Ge
n
e
r
a
l
S
e
w
e
r
P
l
a
n
Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
Strait of Juan De Fuca
Port Townsend Bay
Admiralty Inlet
Kah Tai
Lagoon
Chinese
Gardens
Hamilton Heights
Lift Station
31st Street
Lift Station
Point Hudson
Lift Station
Monroe Street
Lift Station
Gaines Street
Lift Station
Port
Lift Station
Island Vista
Lift Station
Outfall
Port
Esri, HERE,
"L
"L
"L
"L
"L
"L
"L
"L
³³WWTF
Seaview/Howard
Street
Sims Way
West
Hastings
Avenue
Admiralty Avenue
Monroe
Street
San Juan Avenue
Southwest
Discovery
Road
Golf
Course
Gaines
Street
F Street
North Bend
SIMS WAY
HASTINGS AVE
F ST
39TH ST S ST
COO
K
A
V
E
W ST
20TH ST
RA
I
N
I
E
R
S
T
HI
L
L
S
T
P ST
30TH ST
TH
O
M
A
S
S
T
S
J
A
C
O
B
M
I
L
L
E
R
R
D
MILL RD
BLAIN
E
S
T
29TH ST
6TH ST
5TH ST
CH
E
R
R
Y
S
T
43RD ST
49TH ST
1S
T
S
T
.
SA
N
J
U
A
N
A
V
E
25TH ST
7TH ST
JA
C
K
M
A
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S
T
3RD ST
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N
D
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I
C
K
S
S
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22ND ST
2ND ST
IV
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SP
R
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PE
A
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A
V
E
ARCADIA W
N
J
A
C
O
B
M
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L
L
E
R
R
D
27TH ST
JENSEN ST
W
A
L
K
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R
S
T
HA
R
B
O
R
D
E
F
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N
S
E
W
A
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36TH ST
S
8
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HI
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A
I
L
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MIDD
L
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P
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N
T
R
D
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A
R
N
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AL
B
A
T
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S
S
S
T
35TH ST
38TH ST
GI
B
B
S
S
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BA
K
E
R
S
T
JUAN DE FUCA RD
DENNY AVE
BOREN AVE
PERSHING
A
V
E
C
A
P
E
G
E
O
R
G
E
R
D
RAINSHADOW RD
KAN
U
D
R
ALEXANDER'S L
P
EA
S
T
P
A
R
K
A
V
E
35TH ST
IV
Y
S
T
49
T
H
S
T
6TH ST
25TH ST
3RD ST
N
DRAWING IS FULL SCALE
WHEN BAR MEASURES 1”
0 2,0001,000
Feet
1 inch : 2,000 Feet
Legend
City Limits/Urban Growth Area Boundary
Sewer Infrastructure
³³WWTF Wastewater Treatment Facility
"L Lift Station
Force Main
Outfall
Sewer Drainage Basin
Admiralty Avenue
Discovery Road
F Street
Gaines Street
Golf Course
Hastings Avenue
Monroe Street
North Bend
Port
San Juan Avenue
Seaview/Howard Street
Sims Way
Southwest
West
J:
\
D
A
T
A
\
T
W
N
S
D
\
2
1
-
0
2
2
6
\
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:
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1
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r
P
l
a
n
Ge
n
e
r
a
l
S
e
w
e
r
P
l
a
n
Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
Strait of Juan De Fuca
Port Townsend Bay
Admiralty Inlet
Kah Tai
Lagoon
Chinese
Gardens
Hamilton Heights
Lift Station
31st Street
Lift Station
Point Hudson
Lift Station
Monroe Street
Lift Station
Gaines Street
Lift Station
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Port Townsend Wastewater Treatment Facility
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20-Mile Radius
County Boundary
Port Townsend City Limits/Urban Growth Area Boundary
Highway
J:\DATA\TWNSD\21-0226\GIS\2022 GSP UPDATE\2022 GSP UPDATE.APRX BY: MEMOTO PLOT DATE: OCT 25, 2023 COORDINATE SYSTEM: NAD 1983 STATEPLANE WASHINGTON NORTH FIPS 4601 FEET
Vicinity Map
City of Port TownsendCity of Port Townsend
General Sewer PlanGeneral Sewer Plan
WW Treatment Facilities in Vicinity
Figure 2-6 This map is a graphic representation derived
from the City of Port Townsend (City)
Geographic Information System. It was designed
and intended for City staff use only; it is not
guaranteed to survey accuracy. This map is
based on the best information available on the
date shown on this map.
Any reproduction or sale of this map, or portions
thereof, is prohibited without express written
authorization by the City.
This material is owned and copyrighted by the
City.
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This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
Strait of Juan De Fuca
Port Townsend Bay
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Chinese
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Hamilton Heights
Lift Station
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Lift Station
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Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
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J:\DATA\TWNSD\21-0226\10 REPORTS\WIP\TWNSD_GSP CH 3.DOCX (4/25/2024 4:57 PM) 3-1
3 | LAND USE AND POPULATION
INTRODUCTION
The State of Washington Growth Management Act (GMA) requires, among other things,
consistency between land use and utility plans and their implementation. This chapter
demonstrates the compatibility of the City of Port Townsend’s (City) General Sewer Plan (GSP)
with other plans, identifies the designated land uses within the existing and future service area,
and presents population projections within the City’s planning area.
COMPATIBILITY WITH OTHER PLANS AND POLICIES
To ensure that the GSP is consistent with the land use policies that guide it and other related
plans, the following planning documents were examined.
• State of Washington Growth Management Act
• Port Townsend Comprehensive Plan
• Jefferson County County-wide Planning Policies
• Jefferson County Comprehensive Plan
Growth Management Act
The State of Washington GMA of 1990 (and its multiple amendments) defined four goals
relevant to this GSP:
1. Growth should be in urban areas;
2. There should be consistency between land use and utility plans and their
implementation;
3. There should be concurrency of growth with public facilities and services; and
4. Critical areas should be designated and protected.
Urban Growth Area
The GMA requires that Jefferson County (County) designate an Urban Growth Area (UGA)
where most future urban growth and development will be directed. The Countywide UGA is
defined in the Jefferson County Comprehensive Plan and encompasses the area where this
urban growth and development is projected to occur over the 20-year planning period. The
current Jefferson County UGA boundaries in the vicinity of the City are shown on Figure 3-1.
Consistency
The GMA requires planning consistency from two perspectives. First, it requires the consistency
of plans between jurisdictions. This means that plans and policies of the City and County must
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be consistent per Revised Code of Washington (RCW) 36.70A.100. Second, the GMA requires
that the implementation of the GSP be consistent with comprehensive plans (RCW 36.70A.120).
Concurrency
Concurrency means that adequate public facilities and services be provided at the time that
growth occurs. For example, growth should not occur where schools, roads, and other public
facilities are overloaded. To achieve this objective, the GMA directs growth to areas already
served or readily served by public facilities and services (RCW 36.70A.110). It also requires that
when public facilities and services cannot be maintained at an acceptable level of service, the
new development should be prohibited (RCW 36.70A.110).
Critical Areas
The GMA requires that critical areas be designated and protected. Critical areas include aquifer
recharge areas, wetlands, frequently flooded areas, streams, wildlife habitat, landslide hazard
areas, seismic hazard areas, and steep slopes. The City has adopted development regulations
identifying and protecting critical areas as required. The State Environmental Policy Act (SEPA)
Checklist in Appendix F addresses other environmental concerns.
Port Townsend Comprehensive Plan
The Port Townsend Comprehensive Plan was last adopted in 2016. The plan was developed to
describe the City’s vision for the 20-year planning period and to provide goals and policies for
achieving the vision, as well as to meet the requirements of the GMA.
The Land Use Element of the City’s Comprehensive Plan is the City’s vision of how growth and
development should occur over a 20-year horizon. While the Land Use Element goals and
policies set forth general standards for locating land uses, the Land Use Map (Figure 4-1)
indicates geographically where current and future land uses may be appropriate. The Land Use
Map is a blueprint for the development of an area. The City’s existing land use is shown in
Figure 3-1.
The Land Use Element considers the general location of land uses, as well as the appropriate
intensity and density of land uses given the current development trends of the City. The
Transportation, Utilities, and Capital Facilities Elements ensure that new development will be
served adequately without compromising adopted levels of service, which is consistent with the
principal of concurrency as defined in the GMA.
Jefferson County County-wide Planning Policies
Jefferson County and the City adopted a joint resolution establishing the County-wide Planning
Policies on December 21, 1992. The policies are intended to ensure that County and City
comprehensive plans are consistent in accordance with the GMA. The County -wide Planning
Policies are organized into policies related to UGAs, development and urban services, siting of
public facilities, County-wide transportation facilities, affordable housing, economic
CITY OF PORT TOWNSEND GENERAL SEWER PLAN LAND USE AND POPULATION
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development and employment, and rural areas. All the City’s functional plans are required to
be consistent with the County-wide Planning Policies.
Jefferson County Comprehensive Plan
The current version of the Jefferson County Comprehensive Plan was last updated in 2018.
Chapters include the following.
• Land Use
• Natural Resources
• Housing
• Open Space, Parks & Recreation, Historic & Cultural Preservation
• Environment
• Transportation
• Economic Development
• Capital Facilities & Utilities
The County’s plan is focused on ten framework goals, as follows.
I. Preserving Rural Character
II. Sustainable and Suitable Growth Patterns
III. Enhancement of the Rural Economy
IV. Housing Variety and Affordability
V. Allocation of Land to Meet Anticipated Needs
VI. Environmental Consideration
VII. Mobility
VIII. Active and Healthy Living
IX. Continuous and Ongoing Public Involvement
X. Compliant with GMA
The Jefferson County Comprehensive Plan guides development and designates land use in
unincorporated Jefferson County. County Land Use inside the City’s future wastewater service
area (which includes the City’s UGA) is shown in Figure 3-1; the Jefferson County
Comprehensive Plan can be referenced for County Land Use outside the City’s future
wastewater service area.
LAND USE
The wastewater service area includes the City limits, which is also the City’s UGA boundary, for
a total of approximately 7.0 square miles. The Land Use Map, as shown in Figure 3-1, guides
development and can be used to forecast future wastewater flows and loadings. Land use
outside the City is designated by the County, as shown in Figure 3-1.
Approximately 50.5 percent of the area within the City’s future wastewater service area is
designated for residential use, as indicated in Table 3-1. Approximately 13.2 percent of the
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future wastewater service area is designated for open space/parks; approximately 4.6 percent
is designated for commercial use; approximately 3.4 percent is designated for
public/infrastructure use; and approximately 28.3 percent is designated for other land uses or is
undesignated. One key factor to the City’s land use is the extensive amount of land that is
designated as public right-of-way. Approximately 50 percent of the City’s land area is public
right-of-way, leaving nearly half the land undevelopable. This is a result of the pre-platted
nature of the City and the 200-foot by 200-foot block pattern. This factor will be a key item of
discussion in the next Comprehensive Plan update and impacts the amount of land generating
demand on the utility systems.
Table 3-1
Land Use Inside Future Wastewater Service Area
Land Use Type Acres % of Total
Commercial 205 4.6%
Mixed Use 101 2.3%
Marine-Related Use 86 1.9%
Public/Infrastructure 150 3.4%
Park/Open Space 588 13.2%
Residential 2,254 50.5%
Undesignated 1,081 24.2%
Total 4,466 100.0%
Commercial
4.6%
Mixed Use
2.3%Marine-Related Use
1.9%
Public/Infrastructure
3.4%
Park/Open Space
13.2%
Residential
50.5%
Undesignated
24.2%
CITY OF PORT TOWNSEND GENERAL SEWER PLAN LAND USE AND POPULATION
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POPULATION
Household Trends
The City’s residential areas are largely comprised of single-family residences. The City’s 2016
Comprehensive Plan estimated that there were over 5,300 housing units in the City. Of these,
approximately 4,006 housing units (75.2 percent) were single-family residences, approximately
1,101 housing units (20.7 percent) were multi-family residences, and 219 housing units
(4.1 percent) were other types of residences such as mobile homes, boats, and RVs. The City’s
average household size is estimated to be 1.90 persons per household based on the 2020 U.S.
Census Bureau data.
Historical and Future City Population
The City has experienced steady population growth since 2000. The population of the City has
increased by approximately 23 percent over the last 20 years. Table 3-2 illustrates the historical
population growth since 1995. The historical population shown in Table 3-2 represents the
population within the City limits. The sources of the historical population numbers are the
decennial census and Office of Financial Management (OFM) intercensal estimates.
Table 3-2
Population Trends within the City Limits
Projected future population growth within the City Limits, shown in Table 3-3 and Chart 3-1, is
based on current projections from the City’s 2016 Port Townsend Comprehensive Plan. The City
is projected to have a population of 13,300 people in 2043. The buildout population shown in
Table 3-3 is based on data from the City’s previous GSP.
Year City Population
1995 8,165
2000 8,334
2001 8,441
2004 8,543
2007 8,945
2010 9,113
2011 9,240
2012 9,299
2013 9,320
2014 9,504
2015 9,579
2016 9,805
2017 9,871
2018 9,950
2019 10,060
2020 10,148
2021 10,220
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The City is currently discussing an expansion to its sewer service area. Chapter 2 describes
factors to consider in serving a Special Study Area and the expansion that would result. The
expansion of the service area is dependent on coordination with the County, the Department of
Commerce, and the Department of Ecology to ensure compliance with the GMA. The Special
Study Area expansion will extend service to two new sewer basins already inside the City limits
and could serve the Glen Cove Local Area of More Intense Rural Development (LAMIRD) just
outside the City limits. The Special Study Area boundary is approximately shown in Figure 3-2.
For the purposes of estimating demand on the sewer system, an equivalent population for the
industrial area was estimated. The additional population outside of the City limits this
expansion would introduce to the sewer service area is included in Table 3-3 under the
assumption the expansion would start in 2025. Note, the actual population growth would be
considerably less given business customers do not necessarily add more population to the City.
Table 3-3
Population Projections
Year City Population
City Sewer
System Population
Population Served
by Septic Systems
Sewer Service
Expansion Equivalent
Population1
Sewer System
Population with
Expansion
2015 9,579 9,188 391 ----
2016 9,805 9,414 391 ----
2017 9,871 9,480 391 ----
2018 9,950 9,559 391 ----
2019 10,060 9,669 391 ----
2020 10,148 9,757 391 ----
2021 10,220 9,829 391 ----
2022 10,339 9,981 359 ----
2023 10,460 10,134 326 ----
2024 10,582 10,289 294 0 10,289
2025 10,706 10,445 261 108 10,553
2026 10,831 10,603 228 216 10,819
2027 10,958 10,762 196 324 11,086
2028 11,086 10,923 163 432 11,354
2029 11,215 11,085 130 540 11,624
2030 11,346 11,248 98 648 11,896
2031 11,479 11,413 65 755 12,169
2032 11,613 11,580 33 863 12,444
2033 (+10 years)11,748 11,748 0 971 12,720
2034 11,886 11,886 0 1,041 12,927
2035 12,025 12,025 0 1,116 13,140
2036 12,165 12,165 0 1,196 13,361
2037 12,321 12,321 0 1,282 13,603
2038 12,479 12,479 0 1,374 13,853
2039 12,639 12,639 0 1,472 14,111
2040 12,801 12,801 0 1,578 14,379
2041 12,965 12,965 0 1,691 14,656
2042 13,132 13,132 0 1,812 14,944
2043 (+20 years)13,300 13,300 0 1,943 15,242
Buildout 23,035 23,035 0 2,771 25,973
1 = Equivalent population is shown based upon the projected flow and is representative of the growth in terms of population.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN LAND USE AND POPULATION
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Chart 3-1
Population Projections
Sewer System Population
The actual number of people served by the City’s wastewater system is different than the
population of the City limits. The City currently provides sewer service to the entire population
within the City limits, except for 206 residential properties that currently are unsewered. The
unsewered population and the sewer system population inside the City limits was calculated by
multiplying the estimated number of connections by the average household size for the City. As
shown in Table 3-3, the estimated population served by the sewer system in 2021 was 9,829.
Sewer system population projections through 2043 are shown in Table 3-3. It was assumed that
by 2033, the current unsewered properties in the City limits would be connected to the City’s
wastewater system. The wastewater system is expected to provide service to approximately
15,242 people in 2043.
0
2,000
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6,000
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2015 2017 2019 2021 2023 2025 2027 2029 2031 2033 2035 2037 2039 2041 2043
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Base Line Year: 2021
2015 to 2021:
City Population
2021 to 2043:
City Population Projection
2021 to 2043:
Sewer System
Population Projection
2025 to 2043:
Sewer System Population Projection
with Service Area Expansion
+10 Years: 2033
+20 Years: 2043
2015 to 2021:
Sewer System
Population
CHAPTER 3 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Distribution of Population Assumptions
City planning staff made an estimate of where future growth might occur within the existing
sewer service area as shown in the map in Figure 3-3. This population forecast was used to
allocate future flows in the sewer hydraulic model for the 5 -year, 6- to 10-year, and 11- to
20-year design horizons. Flow contributions from the Special Study Area expansion to the Glen
Cove Area to be served by the proposed Mill Lift Station are in addition to these allocations.
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R-II(SF)R-II(SF)
R-II(SF)
R-I(SF)
R-I(SF)
R-I(SF)
R-I(SF)
R-I(SF)R-I(SF)
R-I(SF)R-I(SF)
R-I(SF)R-I(SF)
R-I(SF)
R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)R-II(SF)R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)R-II(SF)R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)R-II(SF)R-II(SF)R-II(SF)R-II(SF)R-II(SF)
R-II(SF)R-II(SF)R-II(SF)
R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)
R-II(SF)R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)R-II(SF)
R-III(MF)R-III(MF)
R-III(MF)
R-III(MF)
R-III(MF)
R-III(MF)
R-III(MF)
M-II(A)C-II/MU
R-II(SF)
R-II(SF)
P/OS(B)P/OS(B)
R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)
R-II(SF)
M-C
P/OS
R-I(SF)
R-I(SF)
R-II(SF)
R-III(MF)
R-I(SF)
M-C
Google
DRAWING IS FULL SCALE
WHEN BAR MEASURES 1”
0 1,000 2,000500
Feet
1 inch : 2,000 Feet
Legend
City Limits/Urban Growth Area Boundary
Existing Land Use - City
Neighborhood Commercial (C-I)
Neighborhood Mixed Use Center (C-I/MU)
General Commercial (C-II)
Hospital Commercial (C-II(H))
Community Mixed Use (C-II/MU)
Historic Commercial (C-III)
Mixed Commercial/Light Manufacturing (M-C)
Marine Related Uses (M-II(A), M-II(B))
Public/Infrastructure (P-I)
Park/Open Space (P/OS)
Public/Mixed Use (P/OS(B))
Single Family Residential - 10,000 SF Lot (R-I(SF))
Single Family Residential - 5,000 SF Lot (R-II(SF)
Multi-Family Residential - 16 Units per 40,000 SF (R-III(MF))
Multi-Family Residential - 24 Units per 40,000 SF (R-IV(MF))
Existing Land Use - Jefferson County
Local Agriculture (JEFF AL-20)
Commercial Forest (JEFF CF-80)
Essential Public Facility-Waste Management (JEFF EPF-WM)
Heavy Industrial (JEFF HI)
Light Industrial (JEFF LI)
Rural Residential (JEFF RR-10)
Rural Residential (JEFF RR-20)
Rural Residential (JEFF RR-5)
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Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
Strait of Juan De Fuca
Port Townsend Bay
Admiralty Inlet
Kah Tai
Lagoon
Chinese
Gardens
Maxar
Esri, HERE, Garmin, USGS,
EPA, NPS
Dis
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Mill Road
Old Fort Townsend Road
St
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0
1 Inch: 1,500 Feet
Legend
Outline of Proposed Mill Site Pump Station Basin
Limited Area of More Intensive Rural Development (LAMIRD)
Existing Sewer Line
DRAWING IS FULL SCALE
WHEN BAR MEASURES 1”
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P
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a
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Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
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DRAWING IS FULL SCALE
WHEN BAR MEASURES 1”
0 2,0001,000
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1 inch : 2,000 Feet
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Vicinity Map
This map is a graphic
representation derived from the
City of Port Townsend (City)
Geographic Information System. It
was designed and intended for City
staff use only; it is not guaranteed
to survey accuracy. This map is
based on the best information
available on the date shown on this
map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the City.
This material is owned and
copyrighted by the City.
Legend
City Limits/Urban Growth Area Boundary
Sewer Infrastructure
Wastewater Treatment Facility
Lift Station
Force Main
Outfall
Gravity Main by Diameter
1- to 4-inch
6-inch
8-inch
10- to 12-inch
14- to 18-inch
22- to 24-inch
30-inch
Unknown
Sewer Drainage Basin
Admiralty Avenue
Discovery Road
F Street
Gaines Street
Golf Course
Hastings Avenue
Monroe Street
North Bend
Port
San Juan Avenue
Seaview/Howard Street
Sims Way
Southwest
West
Population allocations provided by the City of Port Townsend Planning Department, July 2023.
Strait of Juan De Fuca
Port Townsend Bay
Admiralty Inlet
Kah Tai
Lagoon
Chinese
Gardens
Hamilton Heights
Lift Station
31st Street
Lift Station
Point Hudson
Lift Station
Monroe Street
Lift Station
Gaines Street
Lift Station
Port
Lift Station
Island Vista
Lift Station
Wastewater
Treatment Facility
17%
1%
17%
35%
5%
10%
5%
10%
Admiralty Avenue
North Bend
Seaview/Howard Street
San Juan Avenue
Hastings
Avenue
West
Southwest
Sims Way
Discovery
Road
Port
Golf
Course Gaines
Street
Monroe
Street
F Street
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4 | FLOW AND LOADING ANALYSES
INTRODUCTION
A detailed analysis of flow and loading is crucial to the planning efforts of a sewer service
provider. When analyzing a sewer system, the first step is to identify current flow and load
values to determine if the existing system can provide adequate service to its existing
customers under the most crucial conditions in accordance with federal and state laws. A
projected sewer system analysis identifies projected flow and load values to determine where
the system will need to be improved to satisfy projected growth while continuing to meet
federal and state laws.
Flow and load values in a sewer system are used to determine the size of gravity collection
piping, lift station facilities, and force main piping, as well as the size and type of treatment
facilities needed. This information also is used to develop the sewer service provider’s National
Pollutant Discharge Elimination System (NPDES) waste discharge permit, which is required by
the Washington State Department of Ecology (Ecology). Several different flow scenarios were
analyzed for the City of Port Townsend’s (City) sewer system and are addressed in this chapter,
including average annual flow (AAF), maximum month average flow (MMF), maximum day flow
(MDF), peak hour flow (PHF), and projected flows. The City’s wastewater treatment facility
(WWTF) loading, inflow and infiltration (I/I), and peaking factors also are presented.
System design criteria and standards have been develo ped to ensure that a consistent
minimum level of service is maintained throughout the City’s sewer system and to facilitate
planning, design, and construction of sewer system projects. A copy of the City’s Engineering
Design Standards Manual is included in Appendix G. Design requirements for sewer systems
are available in Ecology’s Criteria for Sewage Works Design (commonly known as the “Orange
Book”).
SEWER SERVICE CONNECTIONS AND RESIDENTIAL POPULATION
Sewer Service Connections
Table 4-1 presents the City’s historical sewer service connections for 2015 through 2021. As of
2021, there were approximately 4,710 sewer service connections throughout the City’s sewer
system. Of these connections, 4,265 were residential services and 445 were
commercial/government services. A breakdown of the sewer service connections by customer
class is shown in Chart 4-1.
CHAPTER 4 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table 4-1
Historical Sewer Connections Summary
Chart 4-1
2021 Sewer Service Connections by Customer Class
Sewer Service Population
As presented in Chapter 3, the City’s 2021 sewer service area population is estimated to be
9,829 people. This estimate is based on the City’s population of 10,220 for 2021, and an
average household size of 1.90 for areas in the City limits multiplied by 206 unsewered
residential properties in the City limits. The average household size for areas in the City limits is
based on the City’s Comprehensive Plan, which was amended in 2016. Table 4-2 presents the
City’s historical sewer population for 2015 through 2021.
Year
Residential Sewer
Accounts
Commercial/Government
Sewer Accounts
Total Sewer
Accounts
2015 4,048 425 4,473
2016 4,041 429 4,470
2017 4,103 434 4,537
2018 4,145 436 4,581
2019 4,196 444 4,640
2020 4,238 444 4,682
2021 4,265 445 4,710
Residential
90.5%
Commercial/Government
9.5%
CITY OF PORT TOWNSEND GENERAL SEWER PLAN FLOW AND LOADING ANALYSES
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Table 4-2
Historical Sewer Service Population
The City’s wastewater collection planning area includes the entire Urban Growth Area (UGA).
There are parcels within the City limits that are served by on-site septic systems. Once these
systems fail, City code requires that the homeowners connect to the City’s municipal
wastewater system if the parcel is located within 500 feet of the wastewater collection system.
It is assumed for this General Sewer Plan (GSP) that all of these parcels in the City limits will be
connected to the City’s wastewater collection system by 2033, and the sewer service
population will be the same as the UGA population by 2043. This will ensure that the City has
the infrastructure in place to serve the entire UGA population.
EXISTING WASTEWATER FLOW AND LOADING
Wastewater Flow
The total influent flow to the WWTF is made up of untreated flow from primarily residential
customers, but also includes flow from a number of commercial, hospitality, and retail
businesses, schools, and the Jefferson Healthcare Medical Center. The City’s existing collection
system flow rates were estimated using the WWTF discharge monitoring reports and lift station
run time data for the 2016 through 2021 period. The City’s sewer collection system drainage
basins are shown in Figure 2-1.
The City’s discharge monitoring reports have been reviewed and analyzed to determine current
wastewater characteristics and influent loadings. Table 4-3 summarizes the historical WWTF
AAFs, MMFs, MDFs (including I/I), and PHFs on an annual basis for the 2016 through 2021
period.
Year City Population
Sewer System
Population
2015 9,579 9,188
2016 9,805 9,414
2017 9,871 9,480
2018 9,950 9,559
2019 10,060 9,669
2020 10,148 9,757
2021 10,220 9,829
CHAPTER 4 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table 4-3
Historical WWTF Influent Flow Summary
The monthly average and maximum influent wastewater flows recorded on the WWTF’s
discharge monitoring reports for the 2016 through 2021 period are summarized in Appendix H.
Data from 2020 and 2021 were not included in the historical averages and maximums in
Table 4-3 due to probable shifts in typical wastewater patterns due to the COVID pandemic.
In the 2016 to 2019 period, the average annual flow for the WWTF is 0.84 million gallons per
day (MGD), with the highest AAF of 0.87 MGD occurring in 2018. The AAF for 2016 through
2018 has remained at or above the 4-year average. In 2019, the AAF dropped to 0.78 MGD. The
MDF for the WWTF has varied from year to year over the same 4-year period, with the lowest
MDF of 1.12 MGD occurring in 2019, and the highest MDF of 1.99 MGD occurring in 2016.
The WWTF is currently permitted for a MMF of 2.05 MGD. The City’s NPDES permit stipulates
that the City shall submit a plan and schedule for continuing to maintain capacity when the flow
reaches 85 percent of the permitted flow for 3 consecutive months; 85 percent of the
permitted flow is approximately 1.74 MGD. As Table 4-3 and Appendix H show, this limit has
not been exceeded in the 2016 through 2019 period. The highest MMF of 1.16 MGD
(57 percent of the permitted flow) occurred in 2018. A significant increase in the MMF occurred
from 2017 to 2018; however, the MMF dropped again in 2019 to flows similar to 2017.
Wastewater Loading
The City’s discharge monitoring reports have been reviewed and analyzed to determine current
wastewater characteristics and influent loadings. The 2016 through 2021 historical average
annual and maximum month average 5-day biochemical oxygen demand (BOD5) and total
suspended solids (TSS) loadings in pounds per day (ppd) and pounds per capita per day (ppcd)
are summarized in Tables 4-4 and 4-5, respectively.
MMF/AAF MDF/AAF PHF/AAF
2016 9,414 0.85 91 1.07 1.99 --52%1.26 2.33 --
2017 9,480 0.84 88 0.92 1.39 2.79 45%1.10 1.66 3.33
2018 9,559 0.87 91 1.16 1.82 3.06 57%1.33 2.09 3.52
2019 9,669 0.78 81 0.87 1.12 2.35 43%1.11 1.43 2.99
2020 9,757 0.80 82 1.15 2.37 3.34 56%1.43 2.96 4.17
2021 9,829 0.84 85 1.02 2.18 ---50%1.22 2.60 ---
0.84 88 1.01 1.58 2.74 --1.20 1.88 3.28
0.87 91 1.16 1.99 3.06 --1.33 2.33 3.52
AAF
(MGD)
Sewer System
PopulationYear
Peaking Factors
Percent of NPDES
Permit Max. Month
Limit1
PHF
(MGD)
1 = The City's WWTF is permitted for a maximum month average influent flow of 2.05 MGD.
2 = 2020 and 2021 values are not included in the historical averages and maximums due to the COVID pandemic.
2016 to 2019 Average2
2016 to 2019 Max.2
MDF
(MGD)
MMF
(MGD)
AAF per
Capita
(gpcd)
CITY OF PORT TOWNSEND GENERAL SEWER PLAN FLOW AND LOADING ANALYSES
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Table 4-4
Historical WWTF Influent BOD5 Loading Summary
Table 4-5
Historical WWTF Influent TSS Loading Summary
The average annual and maximum month average BOD5 and TSS loadings in Tables 4-4 and 4-5
were estimated from 2016 through 2019 data. Data from 2020 and 2021 are not included in the
historical averages due to the COVID pandemic. The monthly average and maximum influent
loadings recorded at the WWTF for the 2016 through 2019 period are summarized in
Appendix H.
In the 2016 through 2019 period, the average annual influent BOD5 loading has increased
overall; however, there have been fluctuations throughout that time period with both
significant increases and decreases from year to year. The average annual influent BOD5 and
TSS loadings significantly increased from 2017 to 2018. Average annual BOD5 and TSS loadings
were relatively consistent in 2016 and 2017, before increasing in 2018. As Tables 4-4 and 4-5
show, the average annual BOD5 and TSS loading are relatively similar.
The WWTF currently has a permitted capacity for BOD5 influent maximum month average
loading of 3,754 ppd and a TSS influent maximum month average loading of 4,568 ppd. The
City’s NPDES permit stipulates that the City shall submit a plan and schedule for continuing to
maintain capacity when the loading reaches 85 percent of the permitted loading for
Year
Sewer System
Population
Average
Annual
BOD5
(mg/L)
Average
Annual
BOD5
(ppd)
Average Annual
BOD5
(ppcd)
Max. Month
BOD5
(mg/L)
Max.
Month
BOD5
(ppd)
Percent of NPDES
Permit Max.
Month Limit1
BOD5 Max. Month
Average/Average
Annual Peaking
Factor
2016 9,414 332 2,242 0.24 405 2,442 65%1.09
2017 9,480 329 2,289 0.24 364 2,538 68%1.11
2018 9,559 363 2,509 0.26 454 2,968 79%1.18
2019 9,669 400 2,591 0.27 437 2,718 72%1.05
2020 9,757 336 2,147 0.22 374 2,422 65%1.13
2021 9,829 334 2,221 0.23 393 2,500 67%1.13
356 2,408 0.25 415 2,667 ---1.11
400 2,591 0.27 454 2,968 ---1.18
2016 to 2019 Average2
2016 to 2019 Max.2
1 = The City's WWTF is permitted for a maximum month BOD 5 influent loading of 3,754 ppd.
2 = 2020 and 2021 values are not included in the historical averages and maximums due to the COVID pandemic.
Year
Sewer System
Population
Average
Annual
TSS
(mg/L)
Average
Annual
TSS
(ppd)
Average Annual
TSS
(ppcd)
Max.
Month
TSS
(mg/L)
Max.
Month
TSS
(ppd)
Percent of NPDES
Permit Max. Month
Limit1
TSS Max. Month
Average/Average
Annual Peaking
Factor
2016 9,414 331 2,240 0.24 388 2,458 54%1.10
2017 9,480 329 2,291 0.24 367 2,564 56%1.12
2018 9,559 359 2,493 0.26 431 2,799 61%1.12
2019 9,669 376 2,437 0.25 417 2,686 59%1.10
2020 9,757 341 2,188 0.22 386 2,725 60%1.25
2021 9,829 322 2,146 0.22 390 2,481 54%1.16
349 2,365 0.25 401 2,627 ---1.11
376 2,493 0.26 431 2,799 ---1.12
2016 to 2019 Average2
2016 to 2019 Max.2
1 = The City's WWTF is permitted for a maximum month TSS influent loading of 4,568 ppd.
2 = 2020 and 2021 values are not included in the historical averages and maximums due to the COVID pandemic.
CHAPTER 4 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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3 consecutive months; 85 percent of the permitted loading is 3,191 ppd for BOD5 and 3,883 ppd
for TSS.
As Tables 4-4 and 4-5 show, the BOD5 and TSS influent limits have not been exceeded in the
2016 through 2019 time period. The highest maximum month average BOD5 loading of
2,968 ppd (79 percent of the permitted BOD5 loading) and the highest maximum month
average TSS loading of 2,799 ppd (61 percent of the permitted TSS loading) both occurred in
2018.
INFLOW AND INFILTRATION
I/I is the combination of groundwater and surface water that enters the sewer system.
Infiltration is groundwater entering the sewer system through defects in the sewer system
infrastructure, such as fractured pipes and leaking maintenance holes and pipe joints. Inflow is
surface water that enters the sewer system from sources such as roof and street drains and
leaky maintenance hole covers.
A sanitary sewer system must be able to carry the domestic wastewater generated by utility
customers and the extraneous I/I that is a part of every sewer collection system. Excessive I/I in
the sewer collection system can lead to serious issues within the collection system that may
include wastewater system backups and overflows, accelerating the structural deficiencies of
the collection system. Excessive I/I also can inflate capacity requirements of the proposed
collection and treatment system infrastructure.
Reducing I/I in a sewer collection system can reduce the risk of sanitary sewer overflows and
the cost of treating wastewater. By reducing or eliminating I/I sources, the extraneous water
that previously occupied the conveyance and treatment system can now be occupied by
sewage flows. This leads to delaying conveyance and treatment projects that were needed
because of the extraneous I/I water.
The U.S. Environmental Protection Agency (EPA) published a report in May 1985,
Infiltration/Inflow, I/I Analysis and Project Certification, which developed guidelines to help
determine what amount of I/I is considered to be excessive and what amount can be
cost-effectively removed. The report established I/I flow rates that are considered normal or
acceptable based on surveys and statistical evaluations of data from hundreds of cities across
the nation.
Precipitation and temperature data were compiled from the National Oceanic and Atmospheric
Administration’s (NOAA) website for weather stations in and near the City.
Inflow
The EPA report gives guidelines for determining whether inflow can be classified as
non-excessive. Inflow is considered to be non-excessive if the average daily flow during periods
of heavy rainfall or spring thaw (i.e. any event that creates surface ponding and surface runoff)
does not exceed 275 gallons per capita per day (gpcd). The peak recorded daily flow in the
6 years analyzed for the City (2016 through 2021) was 2.37 MGD, which occurred on
February 5, 2020. Per the weather data obtained from NOAA, this day was recorded as having
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0.95 inches of precipitation. This peak inflow event equates to a 243 gpcd flow rate, which is
below the EPA’s maximum of 275 gpcd. The second peak recorded daily flow was 2.36 MGD,
which occurred on the following day, February 6, 2020. This day was recorded as having
0.4 inches of precipitation. This peak inflow event equates to a 242 gpcd flow rate, which does
not exceed the EPA maximum. The third highest recorded daily flow was 2.18 MGD, which
occurred on January 4, 2021. This day was recorded as having 0.64 inches of precipitation and a
peak inflow equating to 222 gpcd, which is below the EPA’s inflow guideline.
All three peaks are below the EPA’s maximum inflow criterion and are considered
non-excessive. The City should continue to monitor inflow throughout the system , particularly
in areas over 50 years old that previously may have been combined collection systems.
Infiltration
The EPA’s guideline for determination of non-excessive infiltration was based on the national
average for dry weather flow of 120 gpcd. In order for the amount of infiltration to be
considered non-excessive, the average daily flow must be less than 120 gpcd (i.e. a 7- to 14-day
average measured during periods of seasonal high groundwater). Although it can be difficult to
discern between inflow and infiltration, peak inflow will generally occur immediately during or
just after a significant rain event, while peak infiltration will occur during the high groundwater
period that follows prolonged precipitation events.
The peak dry weather flow period in the last 6 years (2016 through 2021) of record for the City,
occurring after a few consecutive days of rain, was the 5-day period from January 22, through
January 26, 2016. This period also was directly preceded by heavy rains, and yielded an average
flow of 1.20 MGD, equating to 128 gpcd. The second highest peak dry weather flow period
occurred during a 13-day period from February 4, through February 16, 2018. This period was
preceded by moderate rainfall and yielded an average flow of 124 gpcd. The third highest peak
dry weather flow period occurred during a 14-day period from February 7, through February
21, 2020. This period directly followed a period of heavy rainfall and yielded an average flow of
121 gpcd. All three events are slightly above the EPA’s maximum infiltration criterion;
therefore, the amount of infiltration is considered excessive. The City should continue to
monitor infiltration throughout the system.
Any I/I studies that are conducted in the future should follow the guid elines defined in Chapter
C-1 of Ecology’s Criteria for Sewage Works Design (commonly known as the “Orange Book”).
Emphasis should be placed on older sections of the City with concrete, vitrified clay, and
asbestos cement mains or in areas suspected of being combined sewers. Lawrence Street is
believed to convey both storm and sanitary sewer. Chapter 10 discusses remediation of this
defect..
PROJECTED WASTEWATER FLOW AND LOADING
The City’s sewer system is projected to add a total of 5,850 additional persons by 2043, using
2018 as the base year. This increase in population includes the sewer system expansion as
discussed in Chapter 3.
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Peaking Factors
Once existing flow rates are measured and defined, projected flow rates can be developed.
Projected flows are used to analyze how well the existing system will perform in the future and
determine improvements required to maintain or improve system function. In order to
establish projected flow scenarios for a sewer system, peaking factors need to be determined
for the existing system, which can then be applied to projected flow rates. Peaking factors are
the ratio of higher flows, such as MDF to AAF.
A maximum peak hour flow of 3.34 MGD, based on the highest PHF from the flow data
analyzed for this GSP, occurred in 2020 during the COVID pandemic. The AAF for 2020 was
lower than typical so the peaking factors were estimated by finding the ratio of the 20 20 PHF to
the 2016 to 2019 average AAF, establishing a PHF/AAF of 4.00 for the WWTF . Table 4-6 shows a
summary of the peaking factors for flows at the City’s WWTF for the 2016 through 2021 period.
Table 4-6
Peaking Factor Summary for Flows
Peaking factors also are developed to determine maximum month average BOD5 and TSS
loading projections. These loading peaking factors are the average historic maximum month to
average annual loadings from 2016 to 2019. Data obtained during the COVID pandemic (2020
and 2021) may not represent normal flow and load conditions. For instance, the data from
these years shows a wider variability in peaking factors; therefore, it is not included in this
calculation. Table 4-7 shows a summary of the peaking factors for loading at the City’s WWTF
for the 2016 through 2021 period.
Max. Month Average Flow/Average Annual Flow (MMF/AAF)1.33
Max. Day Flow/Average Annual Flow (MDF/AAF)1 2.83
Peak Hour Flow/Average Annual Flow (PHF/AAF)1 4.00
Max. Month Average/Average Annual Loading 1.18
Max. Month Average/Average Annual Loading 1.12
Flow
BOD5
TSS
1 = The MDF and PHF for 2016 through 2021 both occurred in 2020 during the COVID pandemic. 2020
had a lower than typical AAF, so the PHF/AAF and MDF/AAF peaking factors were estimated with the
PHF and MDF from this year divided by the average AAF for 2016 through 2019.
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Table 4-7
Peaking Factor Summary for Loadings
The peaking factors presented in Tables 4-6 and 4-7 were used to project flows and loadings in
the following sections.
Projected Wastewater Flow Rates
Once existing flow rates are measured and defined, projected flow rates can be developed.
Projected flows are used to analyze how well the existing system will perform in the future and
determine improvements required to maintain or improve system function.
The projected flows at the WWTF were developed using the following information:
• Projected AAFs were estimated using the 2018 AAF, which is approximately 0.87 MGD,
as the existing baseline. Year 2018 was used as the existing baseline for flow projections
because this was the highest AAF over the last 4 years analyzed.
• The highest AAF per capita for 2016 through 2019 was 91 gpcd (Table 4-3), which
includes I/I and commercial wastewater flows. This value was used for projecting how
much additional wastewater flow the projected population growth would contribute to
the City’s sewer system.
• The flow peaking factors shown in Table 4-6 were used for estimating MMFs, MDFs, and
PHFs from projected AAFs.
• From 2025 to buildout, the population and projected flows include the growth as a
result of expanding the sewer service area as described in Chapter 3.
Summaries of the projected flows for the sewer system population within the City limits,
additional sewer expansion, and the total of the two populations, are presented in Tables 4-8
through 4-10, respectively.
Year
BOD5 Max. Month
Average/Average
Annual Peaking Factor
TSS Max. Month
Average/Average
Annual Peaking Factor
2016 1.09 1.10
2017 1.11 1.12
2018 1.18 1.12
2019 1.05 1.10
2020 1.13 1.25
2021 1.13 1.16
Average1 1.11 1.11
1 = The peaking factors used for projections are the averages of the peaking
factors from 2016 to 2019. 2020 and 2021 values are not included in these
averages due to the COVID pandemic.
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Table 4-8
Projected WWTF Influent Flow for Sewer System Population Within City Limits
Year
Equivalent Sewer
System
Population
Projected AAF
(MGD)1
Projected MMF
(MGD)2
Percent of NPDES
Permit Max.
Month Limit3
Projected MDF
(MGD)4
Projected PHF
(MGD)5
Projected PHF with
Inflow Reduction
(MGD)6
2018 (Baseline)9,559 0.87 1.16 57%1.82 3.06 --
2019 9,669 0.78 0.87 43%1.12 2.35 --
2020 9,757 0.80 1.15 56%2.37 3.34 --
2021 9,829 0.84 1.02 50%2.18 -----
2022 9,981 0.91 1.21 59%2.57 3.63 --
2023 10,134 0.92 1.23 60%2.61 3.69 --
2024 10,289 0.94 1.25 61%2.65 3.75 --
2025 10,445 0.95 1.27 62%2.69 3.80 --
2026 10,603 0.97 1.29 63%2.73 3.86 --
2027 10,762 0.98 1.31 64%2.78 3.92 --
2028 10,923 0.99 1.33 65%2.82 3.98 --
2029 11,085 1.01 1.35 66%2.86 4.04 --
2030 11,248 1.02 1.37 67%2.90 4.10 --
2031 11,413 1.04 1.39 68%2.94 4.16 --
2032 11,580 1.05 1.41 69%2.99 4.22 --
2033 (+ 10 years)11,748 1.07 1.43 70%3.03 4.28 3.86
2034 11,886 1.08 1.44 70%3.07 4.33 3.91
2035 12,025 1.09 1.46 71%3.10 4.38 3.96
2036 12,165 1.11 1.48 72%3.14 4.43 4.02
2037 12,321 1.12 1.50 73%3.18 4.49 4.07
2038 12,479 1.14 1.52 74%3.22 4.54 4.13
2039 12,639 1.15 1.53 75%3.26 4.60 4.19
2040 12,801 1.17 1.55 76%3.30 4.66 4.25
2041 12,965 1.18 1.57 77%3.34 4.72 4.31
2042 13,132 1.20 1.59 78%3.39 4.78 4.37
2043 (+ 20 years)13,300 1.21 1.61 79%3.43 4.84 4.43
Buildout 23,035 2.10 2.80 136%5.94 8.39 7.97
1 = Projected AAFs were estimated by using the 2018 AAF as the baseline and adding 91 gpcd (which was the highest historic flow per capita for 2016 through 2019) multiplied by the projected increase in
sewer population from 2018.
2 = Projected MMFs were estimated by multiplying the projected AAF by the highest historic MMF/AAF peaking factor from 2016 through 2019, which was 1.33 in 2018.
3 = The City's WWTF is permitted for a maximum month average influent flow of 2.05 MGD.
4 = Projected MDFs were estimated by multiplying the projected AAF by the MDF/AAF peaking factor of 2.83.
5 = Projected PHFs were estimated by multiplying the projected AAF by the PHF/AAF peaking factor of 4.00.
6 = Projected PHFs with inflow reduction were estimated by reducing projected PHFs after 2032 by 288 gpm (0.41 MGD) to account for the removal of inflow estimated to be contributed by catch basins
connected to the City's sewer system along Lawrence Street.
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Table 4-9
Projected WWTF Influent Flow for Sewer System Special Study Area Expansion
Year
Equivalent Sewer
System
Population
Projected AAF
(MGD)1
Projected MMF
(MGD)2
Projected MDF
(MGD)3
Projected PHF
(MGD)4
2018 (Baseline)----------
2019 ----------
2020 ----------
2021 ----------
2022 ----------
2023 ----------
2024 0 0.00 0.00 0.00 0.00
2025 108 0.01 0.02 0.04 0.07
2026 216 0.03 0.04 0.08 0.14
2027 324 0.04 0.05 0.12 0.21
2028 432 0.05 0.07 0.15 0.28
2029 540 0.07 0.09 0.19 0.35
2030 648 0.08 0.11 0.23 0.42
2031 755 0.10 0.13 0.27 0.49
2032 863 0.11 0.15 0.31 0.56
2033 (+ 10 years)971 0.12 0.16 0.35 0.63
2034 1,041 0.13 0.17 0.37 0.68
2035 1,116 0.14 0.19 0.40 0.72
2036 1,196 0.15 0.20 0.43 0.77
2037 1,282 0.16 0.22 0.46 0.82
2038 1,374 0.17 0.23 0.49 0.88
2039 1,472 0.19 0.25 0.53 0.94
2040 1,578 0.20 0.27 0.56 1.00
2041 1,691 0.21 0.28 0.60 1.07
2042 1,812 0.23 0.30 0.65 1.14
2043 (+ 20 years)1,943 0.24 0.33 0.69 1.22
Buildout 2,771 0.29 0.39 0.83 1.43
1 = Projected AAFs are based upon the calculated 2033, 2043, and Buildout expansion flows as the baseline. 2024 to 2033 flows were projected with a
straight-line appreciation in conjunction with the City's preference on projected equivalent population growth as a result of the sewer expansion.
2 = Projected MMFs were estimated by multiplying the projected AAF by the highest historic MMF/AAF peaking factor from 2016 through 2019, which was
1.33 in 2018.
3 = Projected MDFs were estimated by multiplying the projected AAF by the MDF/AAF peaking factor of 2.83.
4 = Projected PHFs are based upon the calculated 2033, 2043, and Buildout expansion flows as the baseline. 2024 to 2033 flows were projected with a
straight-line appreciation in conjunction with the City's preference on projected equivalent population growth as a result of the sewer expansion.
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Table 4-10
Total Projected WWTF Flow including Special Study Area Expansion
According to these projections, the WWTF will not exceed the NPDES permit maximum month
limit capacity for flow during the 20-year planning period. However, the City should evaluate
the WWTF for upgrades when the average MMF exceeds 85 percent of the NPDES permit limit.
According to these projections, the City should prepare to plan and design WWTF upgrades for
flow by 2038.
Historical Wastewater Flow by Basin
Table 4-11 shows the historical lift station AAF and PHF rates over the 2016 through
2020 period. These flow rates were developed using the run time records and pumping
capacities for the City’s lift stations.
Year
Equivalent Sewer
System
Population
Projected AAF1
(MGD)
Projected MMF2
(MGD)
Percent of NPDES
Permit Max.
Month Limit3
Projected MDF4
(MGD)
Projected PHF5
(MGD)
Projected PHF with
Inflow Reduction6
(MGD)
2018 (Baseline)9,559 0.87 1.16 57%1.82 3.06 --
2019 9,669 0.78 0.87 43%1.12 2.35 --
2020 9,757 0.80 1.15 56%2.37 3.34 --
2021 9,829 0.84 1.02 50%2.18 -----
2022 9,981 0.91 1.21 59%2.57 3.63 --
2023 10,134 0.92 1.23 60%2.61 3.69 --
2024 10,289 0.94 1.25 61%2.65 3.75 --
2025 10,553 0.96 1.29 63%2.73 3.87 --
2026 10,819 0.99 1.32 65%2.81 4.00 --
2027 11,086 1.02 1.36 66%2.89 4.13 --
2028 11,354 1.05 1.40 68%2.97 4.26 --
2029 11,624 1.08 1.44 70%3.05 4.39 --
2030 11,896 1.11 1.47 72%3.13 4.52 --
2031 12,169 1.13 1.51 74%3.21 4.65 --
2032 12,444 1.16 1.55 76%3.29 4.78 --
2033 (+ 10 years)12,720 1.19 1.59 78%3.38 4.91 4.50
2034 12,927 1.21 1.62 79%3.44 5.01 4.59
2035 13,140 1.24 1.65 80%3.50 5.10 4.69
2036 13,361 1.26 1.68 82%3.56 5.20 4.79
2037 13,603 1.28 1.71 83%3.64 5.31 4.90
2038 13,853 1.31 1.75 85%3.71 5.42 5.01
2039 14,111 1.34 1.78 87%3.79 5.54 5.13
2040 14,379 1.36 1.82 89%3.86 5.66 5.25
2041 14,656 1.39 1.86 91%3.95 5.79 5.38
2042 14,944 1.42 1.90 93%4.03 5.92 5.51
2043 (+ 20 years)15,242 1.46 1.94 95%4.12 6.06 5.65
Buildout 25,806 2.39 3.19 156%6.77 9.82 9.40
1 = Total projected AAF was estimated by adding City limit and sewer system expansion flows together.
2 = Total projected MMF was estimated by adding City limit and sewer system expansion flows together.
3 = The City's WWTF is permitted for a maxium month average influent flow of 2.05 MGD.
4 = Total projected MDF was estimated by adding City limit and sewer system expansion flows together.
5 = Total projected PHF was estimated by adding City limit and sewer system expansion flows together.
6 = Projected PHFs with inflow reduction were estimated by reducing projected PHFs after 2032 by 288 (0.41 MGD) to account for the removal of inflow estimated to be contributed by catch basins connected
to the City's sewer system along Lawrence Street.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN FLOW AND LOADING ANALYSES
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Table 4-11
Historical AAF and PHF Rates by Lift Station
The peak hour flow rates for the Gaines Street and Monroe Street Lift Stations are surprisingly
close in magnitude considering that the Gaines Street basin is larger. The Gaines Street basin
serves approximately 500 equivalent residential units (ERUs) more than the Monroe Street
basin, which indicates the flow rate per ERU in the Monroe Street basin is much higher than the
Gaines Street basin. As portions of the Lawrence Street sewer are still combined storm and
sanitary sewer conveyance, this would correlate to higher flows in the Monroe Street basin.
Recorded data from the pump station’s supervisory control and data acquisition (SCADA)
systems was used to calculate the base flows for each pump station. Base flow information for
the Gaines Street Lift Station is based on a magnetic flow meter that records daily totalized
flows. For the Monroe Street Lift Station, timed flow tests were used to verify the station’s
discharge capacity. Run time records were used to multiply the measured flow rates by the run
time to determine the station’s peak hour. RH2 recommends the City begin recording flow
totalizations at the Gaines Street Lift Station on an hourly basis to provide an improved
calculation of the peak hour flow.
Projected Wastewater Flow by Basin
The City is planning for additional growth; however, it is uncertain where growth will occur
within the UGA. City planning staff made an estimate of where the future growth might occur
as shown in Figure 3-3. This population forecast was used to allocate future flows in the sewer
hydraulic model for 5-, 10- and 20-year design horizons, as shown in Table 4-12. The additional
flow associated with the projected population, allocated as shown in Figure 3-3, was calculated
using the per capita domestic and I/I rates developed in Chapter 3 with a peak hour factor of 4.
AAF
(gpm)
PHF
(gpm)
AAF
(gpm)
PHF
(gpm)
AAF
(gpm)
PHF
(gpm)
AAF
(gpm)
PHF
(gpm)
AAF
(gpm)
PHF
(gpm)
AAF
(gpm)
PHF
(gpm)
Gaines Street 1,500 203 1,120 188 1,027 189 982 171 853 173 1,047 185 1,006
Monroe Street 857 144 9903 135 990 136 990 124 916 127 990 133 990
Port 195 23 143 21 143 21 85 19 222 20 163 21 151
Island Vista 135 4 18 4 29 5 47 5 38 3 20 4 31
Hamilton Heights 250 10 38 10 33 10 33 10 33 11 33 10 34
31st Street 100 2 15 2 12 2 13 2 13 2 17 2 14
Point Hudson2 150 ------------------------------------
WWTF ---593 ---582 1,940 604 2,127 545 1,631 557 2,323 555 2,005
3 = 990 gpm, estimated from existing pump curves, is representative of all three pumps in the Monroe Street Lift Station running simultaneously.
1 = Highlighted flows in gray exceed current firm pumping capacity.
2 = Point Hudson Lift Station is not connected to the City's SCADA system.
2017 2018 2019 2020
2016 to 2020
Average
Lift Station1
Existing Design
Firm Capacity
(gpm)
2016
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Table 4-12
Existing and Projected AAF and PHF Rates by Basin
Refer to Chapter 3 for more information regarding the development of population growth.
Refer to Chapter 6 for more information regarding the collection system evaluation.
Lift Station Hydraulic Capacity Analyses
Current lift station pumping capacities based on the calculated and measured flow rates, as well
as the remaining capacity of each lift station , are provided in Table 4-13.
The remaining capacity is presented in terms of the remaining population each lift station is
capable of supporting and is based upon a maximum per capita AAF of 91 gpcd and a PHF/AAF
peaking factor of 4.00.
Table 4-13
Current AAF and PHF Rates and Remaining Capacity by Lift Station
As indicated in Table 4-13, all lift stations, with the exception of Monroe Street, have the
capacity to support existing flows from their basins. There are many instances of all three
pumps in the Monroe Street Lift Station running, which may be indicative of the lift station
Basin
AAF
(gpm)
PHF
(gpm)
AAF
(gpm)
PHF
(gpm)
AAF
(gpm)
PHF
(gpm)
AAF
(gpm)
PHF
(gpm)
Monroe Street 135 542 189 757 191 763 194 775
North Bend 10 42 12 50 14 55 16 64
Seaview/Howard Street 30 121 39 155 44 175 53 213
Southwest --------
West --------
Discovery Road 82 329 100 400 111 443 131 524
Sims Way 63 250 140 562 202 809 324 1296
San Juan Avenue 33 131 38 152 41 164 47 188
Port 21 84 21 84 21 84 21 84
Admiralty Avenue 39 158 42 168 44 175 47 186
Golf Course 19 77 24 98 28 110 34 134
Gaines Street 31 125 31 125 31 122 34 134
F Street 18 74 21 84 23 91 26 103
Hastings Avenue 74 297 92 368 103 411 123 492
Existing 2023 Projected 2028 Projected 2038 Projected 2043
The flows shown in this table are the summation of the sanitary loads assigned to the respective drainage basin in the hydraulic model and do not
include cumulative gravity or pumped flows from upstream basins.
Lift Station1
Existing Design
Firm Capacity
(gpm)
AAF
(gpm)
PHF
(gpm)
Remaining AAF
Capacity
(gpm)
Remaining PHF
Capacity
(gpm)
Remaining AAF
Population
Remaining PHF
Population
Gaines Street 1,500 189 1,194 1,311 306 20,740 1,209
Monroe Street 857 136 990 721 -133 11,398 -526
Port 195 21 85 174 111 2,757 438
Island Vista 135 5 18 130 117 2,062 464
Hamilton Heights 250 10 38 240 212 3,797 838
31st Street 100 2 7 98 93 1,554 369
Point Hudson2 150 1 4 149 146 2,357 578
1 = Highlighted flows in gray exceed current firm pumping capacity.
2 = Point Hudson Lift Station is not connected to the City's SCADA system, so the existing flow for this basin was estimated from the number of homes in this sewer basin.
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being unable to convey the peak flows using only two of the three pumps in the station (the
desired standard). Capacity upgrades to this lift station will be necessary in the future to handle
projected flows. The Monroe Street basin also experiences the greatest levels of I/I relative to
other basins in the City. Operations staff states that the Monroe Street Lift Station discharge
surcharges with three pumps operating simultaneously during peak flows but does not
overflow.
The City is planning to perform an I/I study to identify improvements that could reduce I/I in the
sewer system. These I/I improvements could reduce or mitigate the I/I component of the PHFs
in the City’s sewer collection system, which could reduce or mitigate projected flows. For
example, it is known that Lawrence Street has storm inlets connected to the sanitary sewer.
Capacity upgrades to the Monroe Street Lift Station should be performed following with the
removal of upstream inflow sources.
Besides the Monroe Street Lift Station, the City’s lift stations have ample capacity to convey
future flows for the 20-year design horizon (Table 4-13). Most of the projected growth will
originate in the Mill site area and be pumped by the new Mill Lift Station. All of the discharge
from this station will flow by gravity to the WWTF, posing no new loads to existing lift stations.
Gravity conveyance upgrades will be substantial, but lift station capacity upgrades will not.
Equipment replacements for the City’s lift stations will be needed as it wears out, bu t these
costs will be covered under a maintenance line item as described in the Capital Improvement
Plan in Chapter 10.
Projected Wastewater Loading Capacity
Once existing influent loadings are determined, projected loading capacities can be developed.
Projected loadings are used to project future WWTF loading capacities and determine
improvements required to increase treatment capacity.
The projected BOD5 and TSS loadings at the WWTF were developed using the following
information:
• Average annual BOD5 loadings were projected using the 2019 average annual loadings
as the baseline and adding 0.20 ppcd, which is the average annual BOD5 loading per
capita per day defined in the Orange Book, multiplied by the projected increase in sewer
population from 2019. This estimation from the Orange Book represents residential
contributions to loading, and it is assumed that the City’s projected population growth
will be mainly residential.
• Average annual TSS loadings were projected using the 2018 average annual load ings as
the baseline and adding 0.20 ppcd multiplied by the projected increase in sewer
population from 2018, similar to the BOD5 loading projections.
• The loading peaking factors shown in Table 4-7 were used for estimating maximum
month average loadings from projected average annual loadings.
• From 2025 to buildout, the population includes the growth as a result of expanding the
sewer service area as described in Chapter 3.
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Summaries of the projected BOD5 and TSS loadings for the sewer system population within City
limits, additional sewer expansion, and the total of the two populations, are presented in
Tables 4-14 through 4-19, respectively.
Table 4-14
Projected WWTF Influent BOD5 Loading for Sewer System Population Within City Limits
Year
Equivalent Sewer
System
Population
Projected Average
Annual BOD5
(ppd)1
Projected Max.
Month Average
BOD5
(ppd)2
Percent of NPDES
Permit Max.
Month Limit3
2018 9,559 2,509 2,968 79%
2019 (Baseline)9,669 2,591 2,718 72%
2020 9,757 2,147 2,422 65%
2021 9,829 2,221 2,500 67%
2022 9,981 2,654 2,939 78%
2023 10,134 2,684 2,973 79%
2024 10,289 2,715 3,007 80%
2025 10,445 2,747 3,042 81%
2026 10,603 2,778 3,077 82%
2027 10,762 2,810 3,112 83%
2028 10,923 2,842 3,148 84%
2029 11,085 2,875 3,184 85%
2030 11,248 2,907 3,220 86%
2031 11,413 2,940 3,257 87%
2032 11,580 2,974 3,293 88%
2033 (+ 10 years)11,748 3,007 3,331 89%
2034 11,886 3,035 3,361 90%
2035 12,025 3,063 3,392 90%
2036 12,165 3,091 3,423 91%
2037 12,321 3,122 3,458 92%
2038 12,479 3,153 3,493 93%
2039 12,639 3,185 3,528 94%
2040 12,801 3,218 3,564 95%
2041 12,965 3,251 3,600 96%
2042 13,132 3,284 3,637 97%
2043 (+ 20 years)13,300 3,318 3,674 98%
Buildout 23,035 5,265 5,831 155%
1 = Projected average annual BOD 5 loadings were estimated by using the 2019 average annual BOD 5 loading as the baseline and
adding 0.20 ppcd (which is the BOD 5 loading per capita per day as defined in Ecology's Criteria for Sewage Works Design ) multiplied
by the projected increase in sewer population from 2019.
2 = Projected maximum month average BOD 5 loadings were estimated by multiplying the projected average annual BOD 5 loading by
the average historic maximum month to average annual BOD 5 loading peaking factor from 2016 through 2019, which was 1.11.
3 = The City's WWTF is permitted for a maximum month average influent BOD 5 loading of 3,754 ppd.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN FLOW AND LOADING ANALYSES
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Table 4-15
Projected WWTF Influent BOD5 Loading for Sewer System Special Study Area Expansion
Year
Equivalent Sewer
System
Population1
Projected Average
Annual BOD5
(ppd)2
Projected Max.
Month Average
BOD5
(ppd)3
2024 0 0 0
2025 108 22 24
2026 216 43 48
2027 324 65 72
2028 432 86 96
2029 540 108 120
2030 648 130 143
2031 755 151 167
2032 863 173 191
2033 (+ 10 years)971 194 215
2034 1,041 208 231
2035 1,116 223 247
2036 1,196 239 265
2037 1,282 256 284
2038 1,374 275 304
2039 1,472 294 326
2040 1,578 316 350
2041 1,691 338 375
2042 1,812 362 401
2043 (+ 20 years)1,943 389 430
Buildout 2,771 554 614
1 = Projected equivalent populations were estimated as a straight line appreciation from 2024 to 2033 per
the City's preference on sewer expansion.
2 = Projected average annual BOD 5 loadings were estimated by multiplying the projected equivalent
populations by 0.20 ppcd (which is the BOD5 loading per capita per day as defined in Ecology's Criteria for
Sewage Works Design ).
3 = Projected maximum month average BOD 5 loadings were estimated by multiplying the projected average
annual BOD5 loading by the average historic maximum month to average annual BOD5 loading peaking
factor from 2016 through 2019, which was 1.11.
CHAPTER 4 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table 4-16
Total Projected WWTF BOD5 Loading including Special Study Area Expansion
According to these projections, the WWTF will exceed the NPDES permit maximum month limit
capacity for BOD5 during the 20-year planning period. However, the City should prepare the
WWTF for upgrades when the maximum month average BOD5 load exceeds 85 percent of the
NPDES permit limit. According to these projections, the City will need to start planning and
designing WWTF upgrades by 2027. If the special study area expansion is not implemented,
then these upgrades will be delayed until 2029.
Year
Equivalent Sewer
System
Population
Projected Average
Annual BOD5
(ppd)1
Projected Max.
Month Average
BOD5
(ppd)2
Percent of NPDES
Permit Max.
Month Limit3
2018 9,559 2,509 2,968 79%
2019 (Baseline)9,669 2,591 2,718 72%
2020 9,757 2,147 2,422 65%
2021 9,829 2,221 2,500 67%
2022 9,981 2,654 2,939 78%
2023 10,134 2,684 2,973 79%
2024 10,289 2,715 3,007 80%
2025 10,553 2,768 3,066 82%
2026 10,819 2,821 3,125 83%
2027 11,086 2,875 3,184 85%
2028 11,354 2,928 3,243 86%
2029 11,624 2,982 3,303 88%
2030 11,896 3,037 3,363 90%
2031 12,169 3,091 3,424 91%
2032 12,444 3,146 3,485 93%
2033 (+ 10 years)12,720 3,202 3,546 94%
2034 12,927 3,243 3,592 96%
2035 13,140 3,286 3,639 97%
2036 13,361 3,330 3,688 98%
2037 13,603 3,378 3,741 100%
2038 13,853 3,428 3,797 101%
2039 14,111 3,480 3,854 103%
2040 14,379 3,533 3,913 104%
2041 14,656 3,589 3,975 106%
2042 14,944 3,646 4,039 108%
2043 (+ 20 years)15,242 3,706 4,105 109%
Buildout 25,806 5,819 6,445 172%
1 = Projected average annual BOD 5 loadings were estimated by adding City limit and sewer system expansion loadings together.
2 = Projected maximum month average BOD 5 loadings were estimated by adding City limit and sewer system expansion loadings
together.
3 = The City's WWTF is permitted for a maximum month average influent BOD 5 loading of 3,754 ppd.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN FLOW AND LOADING ANALYSES
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Table 4-17
Projected WWTF Influent TSS Loading for Sewer System Population Within City Limits
Year
Equivalent Sewer
System
Population
Projected Average
Annual TSS
(ppd)1
Projected Max.
Month Average
TSS
(ppd)2
Percent of NPDES
Permit Max.
Month Limit3
2018 (Baseline)9,559 2,493 2,799 61%
2019 9,669 2,437 2,686 59%
2020 9,757 2,188 2,725 60%
2021 9,829 2,146 2,481 54%
2022 9,981 2,577 2,862 63%
2023 10,134 2,608 2,896 63%
2024 10,289 2,639 2,930 64%
2025 10,445 2,670 2,965 65%
2026 10,603 2,702 3,000 66%
2027 10,762 2,734 3,035 66%
2028 10,923 2,766 3,071 67%
2029 11,085 2,798 3,107 68%
2030 11,248 2,831 3,143 69%
2031 11,413 2,864 3,180 70%
2032 11,580 2,897 3,217 70%
2033 (+ 10 years)11,748 2,931 3,254 71%
2034 11,886 2,958 3,285 72%
2035 12,025 2,986 3,315 73%
2036 12,165 3,014 3,347 73%
2037 12,321 3,045 3,381 74%
2038 12,479 3,077 3,416 75%
2039 12,639 3,109 3,452 76%
2040 12,801 3,141 3,488 76%
2041 12,965 3,174 3,524 77%
2042 13,132 3,208 3,561 78%
2043 (+ 20 years)13,300 3,241 3,599 79%
Buildout 23,035 5,188 5,760 126%
1 = Projected average annual TSS loadings were estimated by using the 2018 average annual TSS loading as the baseline and adding
0.20 ppcd (which is the TSS loading per capita per day as defined in Ecology's Criteria for Sewage Works Design ) multiplied by the
projected increase in sewer population from 2018.
2 = Projected maximum month average TSS loadings were estimated by multiplying the projected average annual TSS loading by the
average historic maximum month to average annual TSS loading peaking factor from 2016 through 2019, which was 1.11.
3 = The City's WWTF is permitted for a maximum month average influent TSS loading of 4,568 ppd.
CHAPTER 4 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table 4-18
Projected WWTF Influent TSS Loading for Sewer System Special Study Area Expansion
Year
Equivalent Sewer
System
Population1
Projected Average
Annual TSS
(ppd)2
Projected Max.
Month Average
TSS
(ppd)3
2024 0 0 0
2025 108 22 24
2026 216 43 48
2027 324 65 72
2028 432 86 96
2029 540 108 120
2030 648 130 144
2031 755 151 168
2032 863 173 192
2033 (+ 10 years)971 194 216
2034 1,041 208 231
2035 1,116 223 248
2036 1,196 239 266
2037 1,282 256 285
2038 1,374 275 305
2039 1,472 294 327
2040 1,578 316 350
2041 1,691 338 376
2042 1,812 362 402
2043 (+ 20 years)1,943 389 431
Buildout 2,771 554 615
1 = Projected equivalent populations were estimated as a straight line appreciation from 2024 to 2033 per
the City's preference on sewer expansion.
2 = Projected average annual TSS loadings were estimated by multiplying the projected equivalent
populations by 0.20 ppcd (which is the TSS loading per capita as defined in Ecology's Criteria for Sewage
Works Design ).
3 = Projected maximum month average TSS loadings were estimated by multiplying the projected average
annual TSS loading by the average historic maximum month to average annual TSS loading peaking factor
from 2016 through 2019, which was 1.11.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN FLOW AND LOADING ANALYSES
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Table 4-19
Total Projected WWTF TSS Loading including Special Study Area Expansion
According to these projections, the WWTF will not exceed the NPDES permit maximum month
limit capacity for TSS during the 20-year planning period. However, the City should prepare the
WWTF for upgrades when the maximum month average TSS load exceeds 85 percent of the
NPDES permit limit. According to these projections, the City should prepare for WWTF upgrades
for TSS by 2041.
Year
Equivalent Sewer
System
Population
Projected Average
Annual TSS
(ppd)1
Projected Max.
Month Average
TSS
(ppd)2
Percent of NPDES
Permit Max.
Month Limit3
2018 (Baseline)9,559 2,493 2,799 61%
2019 9,669 2,437 2,686 59%
2020 9,757 2,188 2,725 60%
2021 9,829 2,146 2,481 54%
2022 9,981 2,577 2,862 63%
2023 10,134 2,608 2,896 63%
2024 10,289 2,639 2,930 64%
2025 10,553 2,692 2,989 65%
2026 10,819 2,745 3,048 67%
2027 11,086 2,798 3,107 68%
2028 11,354 2,852 3,167 69%
2029 11,624 2,906 3,227 71%
2030 11,896 2,960 3,287 72%
2031 12,169 3,015 3,347 73%
2032 12,444 3,070 3,408 75%
2033 (+ 10 years)12,720 3,125 3,470 76%
2034 12,927 3,167 3,516 77%
2035 13,140 3,209 3,563 78%
2036 13,361 3,253 3,612 79%
2037 13,603 3,302 3,666 80%
2038 13,853 3,352 3,721 81%
2039 14,111 3,403 3,779 83%
2040 14,379 3,457 3,838 84%
2041 14,656 3,513 3,900 85%
2042 14,944 3,570 3,964 87%
2043 (+ 20 years)15,242 3,630 4,030 88%
Buildout 25,806 5,742 6,376 140%
1 = Projected average annual TSS loadings were estimated by adding City limit and sewer system expansion loadings together.
2 = Projected maximum month average TSS loadings were estimated by adding City limit and sewer system expansion loadings
together.
3 = The City's WWTF is permitted for a maximum month average influent TSS loading of 4,568 ppd.
CHAPTER 4 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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SUMMARY
Table 4-20 provides a summary of the existing, 10-year (2033), planning year (2043), and
buildout flow, and BOD5 and TSS loadings for the City’s wastewater collection and treatment
systems.
Table 4-20
Summary of Existing and Projected Flow and Loading at the WWTF
Existing
(2018)
Projected
2033
Projected
2043
Projected
Buildout
Average Annual Flow 0.87 1.19 1.46 2.39
Max. Month Average Flow 1.16 1.59 1.94 3.19
Max. Day Flow 1.82 3.38 4.12 6.77
Peak Hour Flow 3.06 4.91 6.06 9.82
Existing
(2019)
Projected
2033
Projected
2043
Projected
Buildout
Average Annual BOD 5 2,591 3,202 3,706 5,819
Max. Month Average BOD 5 2,718 3,546 4,105 6,445
Existing
(2018)
Projected
2033
Projected
2043
Projected
Buildout
Average Annual TSS 2,493 3,125 3,630 5,742
Max. Month Average TSS 2,799 3,470 4,030 6,376
Flow
(MGD)
BOD5
(ppd)
TSS
(ppd)
J:\DATA\TWNSD\21-0226\10 REPORTS\WIP\TWNSD_GSP CH 5.DOCX (4/29/2024 9:54 AM) 5-1
5 | POLICIES AND COLLECTION SYSTEM DESIGN
CRITERIA
INTRODUCTION
The City of Port Townsend (City) operates and plans sewer service for the City and associated
sewer service area residents and businesses according to the design criteria, laws, and policies
that originate from the U.S. Environmental Protection Agency (EPA) and the Washington State
Department of Ecology (Ecology).
These laws, design criteria, and policies guide the City’s operation and maintenance of the
sewer system on a daily basis, as well as the City’s plan for growth and improvements. The
overall objective is to ensure that the City provides high quality sewer service at a fair and
reasonable cost to its customers. These laws, design criteria, and policies also set the standards
the City must meet to ensure that the sewer system is adequate to meet existing and future
flows. The collection system’s ability to handle these flows is detailed in Chapter 6, and the
analysis of the existing wastewater treatment system is detailed in Chapter 7. The
recommended improvements for the collection system and wastewater treatment systems are
identified in Chapter 10.
The City Council adopts regulations and policies that cannot be less stringent or in conflict with
those established by the federal and state governments. The City’s policies take the form of
ordinances, memoranda, and operational procedures, many of which are summarized in this
chapter.
The City will maintain an updated General Sewer Plan (GSP) that is coordinated with the Land
Use Element of the Comprehensive Plan so that new development will be located where
sufficient sewer system capacity exists or where the collection system can be efficiently and
logically extended.
The policies associated with the following categories are presented in this chapter.
• Regulations
• Customer Service
• Collection System
• Lift Stations
• Operational
• Organizational
• Financial
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REGULATIONS
National Pollutant Discharge Elimination System Permit
Wastewater discharge into surface waters of the State shall have a National Pollutant Discharge
Elimination System (NPDES) permit from Ecology. Refer to Chapter 2 for details on the City’s
NPDES permit. The permit contains a flow limit, influent and effluent quality standards,
monitoring requirements, pretreatment requirements, and system maintenance requirements.
A copy of the City’s NPDES permit is included in Appendix C.
Other Regulations and Required Permits
Refer to Chapter 2 for other regulations and required permits that apply to the City’s
Wastewater Treatment Facility (WWTF). In addition, Chapter 173-240 Washington
Administrative Code (WAC) defines requirements for wastewater facilities plans and reports,
and the City follows the guidelines in Ecology’s 2008 Criteria for Sewage Works Design (Orange
Book).
CUSTOMER SERVICE POLICIES
• Evaluate the prioritization of capital facilities to serve the housing and density needs of
the City based on the upcoming 2025 periodic update. This likely will replace the current
Policy 14.2, concerning tiers, in the Land Use Element of the Comprehensive Plan.
Existing Sewer Service and Connection
• Prioritize capital facilities, services, and utilities within the urban growth tiers per Policy
14.2 of the Comprehensive Plan and Title 13 of the Port Townsend Municipal Code
(PTMC). PTMC 13.01.120 addresses City participation when funds are available as
identified in the 6-year capital facilities plan. Chapter 13.23 specifies that in Tier 1, the
City will participate in sewer extensions when existing structures connected to an
on-site septic system benefit. Historic implementation of the tiering system has not
occurred due to the lack of funding for such sewer extensions. As a result, sewer
extensions have occurred at the cost of the developer who often has utilized the
latecomer fee process for potential reimbursement from benefiting properties.
• Increase the capacity of the collection system and WWTF to reflect increased usage
trends influenced by the City’s growth and economic development per Policy 14.3 of the
Comprehensive Plan Land Use Element.
• As the City’s Urban Growth Area (UGA) is the same as the City’s sewer service area,
sewer service shall not extend beyond the City limits.
• Provide sewer service to properties within the City’s sewer service area, provided all
policies related to service can be met. Ensure that existing and new developments
within the UGA have WWTF and collection line capacities to meet their needs, as well as
State and federal discharge standards.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN POLICIES AND COLLECTION SYSTEM DESIGN CRITERIA
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• Chapter 13.22 PTMC requires all properties that develop or redevelop within the City
limits to connect to the City’s sewer system when the development is located within
260 feet of a wastewater collection line with the following exception: new single-family
residences that are more than 260 feet from the nearest City sewer main and are
subject to review under Chapter 19.05 PTMC, Critical Areas, and the impacts of the
system are adequately mitigated and conditioned through critical areas review. Any
development that is a subdivision, short plat, or Planned Unit Development subject to
PTMC Title 18, a land use or permit approval that requires a threshold determination
under Chapter 19.04 PTMC, or structures (other than single-family residences) subject
to the Critical Areas ordinance all require sewer connection regardless of location.
Additionally, any on-site septic systems must be approved by the Jefferson County
Public Health and be on a lot of sufficient size to meet the requirements for on-site
systems.
• Sewer system extensions, required to provide sewer service to proposed developments,
shall be approved by the Department of Public Works and must comply with the City’s
most current, adopted Engineering Design Standards, PTMC Title 13, all applicable
Revised Codes of Washington (RCWs) and WACs, guidance administered by Ecology, and
the WSDOT/APWA Standard Specifications. All costs of the extension shall be borne by
the developer or applicant. The City’s Wastewater Engineering Standards are included in
Appendix G.
• For sewer service applications within the City limits, the City will review the availability
for sewer service at the time of utility development permit review. During the utility
development permitting process, the City will determine if sewer is available for the site
and will address the sizing and location of the sewer extension.
• Sewer collection system, lift station, and WWTF capacity will be considered when
providing sewer availability to applicants.
• Sewer availability shall expire at the time that the utility development permit expires.
• Time extensions in regard to sewer availability shall be granted in accordance with the
associated permit requirements and PTMC.
• Chapters 13.21 through 13.24 PTMC provide regulations for the City’s sanitary sewer
system.
Proposed Sewer Service and Connection Policies
The following proposed policies are part of this GSP through its adoption by the City Council
and approval by Ecology. These proposed policies will need to be memorialized as part of the
2025 periodic Comprehensive Plan adoption, as well as updates to the PTMC and the
Engineering Design Standards.
• As the City’s Urban Growth Area (UGA) is the same as the City’s sewer service area,
sewer service shall not extend beyond the City limits except as permitted by the Growth
Management Act and governing laws according to the Special Study Area expansion
described in Chapter 2.
CHAPTER 5 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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• Remove and replace the ineffective tiering system with an alternative approach to
achieving the goals of the City concerning sewer extensions.
• Develop policies and incentives to maximize density, including multi-family
development.
• Develop policies and incentives to support affordable and attainable housing. For the
purpose of this policy, attainable housing will need to be defined in terms of
affordability levels or housing type.
• Develop policies to minimize the use of on-site septic systems while recognizing the
requirements of WAC 246-272A-0025, which the local health officer is required to
follow. This WAC allows for the development of on-site septic systems when a property
is located more than 200 feet from a public sewer main. This provision does not apply to
land use actions such as subdivisions.
• Develop sewer extension regulations related to pre-platted plots incentivizing
development of density on pre-platted lots or preservation of pre-platted lots for future
development. This goal is to discourage the combination of pre-platted lots.
Septic System Policies
• Currently, 211 properties within the City limits have been identified as using on-site
sewage systems. According to the Growth Management Act, no new on-site septic
sewage systems should be allowed in the UGA as new development is intended to b e at
urban densities that require sewers. In addition, Chapter 70.118 RCW requires counties
to develop and implement management plans for on-site sewage systems.
• No new on-site septic systems are allowed inside the City limits on properties where
existing City sewer main is within 260 feet of the boundary of the subject property
according to PTMC.
• Existing single-family homes with septic systems are required to connect to the City’s
sewer system unless the nearest sewer main is greater than 260 feet. All septic systems
in the City shall be monitored per Jefferson County Public Health regulations.
• All non-developing properties that annex into the City are encouraged to phase out their
septic systems and connect to the City’s municipal sewer system.
• Property owners with a failing septic system, as documented by Jefferson County Public
Health, shall connect to the City’s sewer system unless the parcel is greater than
260 feet from the nearest existing sewer main, in which case the septic system may be
repaired.
• The City is aware of Engrossed Senate Bill (ESB) 5871, which became effective on
July 24, 2015, and requires cities, towns, and counties to offer an administrative appeals
process to consider denials of permit applications to repair or replace a septic system
where connection to a sewer system is required for single-family residences. The City
will review appeals to repair or replace septic systems as they are submitted in
accordance with ESB 5871.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN POLICIES AND COLLECTION SYSTEM DESIGN CRITERIA
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COLLECTION SYSTEM POLICIES AND DESIGN CRITERIA
Sanitary Sewer Design Criteria
• Standards for sewer system facilities are defined by WAC 173-240-050.
• All sewer lines and facilities within the City shall be designed in accordance with good
engineering practice by a professional engineer with the minimum design criteria
presented in the Criteria for Sewage Works Design, prepared by Ecology, August 2008,
or as superseded by subsequent updates. Chapter C1 of this document includes
standards and guidelines for design considerations (e.g., minimum pipe sizes, pipe
slopes, and wastewater velocities), maintenance considerations, estimating wastewater
flow rates, maintenance hole locations, leak testing, and separation from other
underground utilities. These criteria have been established to ensure that the sanitary
sewers convey the sewage and protect the public health and environment. The sewer
lines also shall conform to the latest regulatory requirements relating to design.
• Sewers shall be designed and constructed in accordance with the City’s most current
Wastewater Engineering Standards.
Gravity Sewer Design Criteria
• All sewers shall be designed as a gravity sewer whenever feasible and buried at a
minimum depth of 5 feet. Exceptions to depth requirements may be made on a limited
basis to facilitate gravity sewer extension.
• The layout for extensions shall provide for the future continuation of the existing system
as determined by the City. The smallest diameter sewer allowed is 8 inches for gravity
mains. A 6-inch sewer may be approved when expansion to serve future customers is
not expected.
• Side sewer connection laterals within City rights-of-way shall be 6 inches at a minimum,
and side sewer laterals on private property shall be 4 inches at a minimum, in
accordance with the Standard Details.
• A 6-inch-diameter lateral is required at a minimum for all commercial, industrial, and
multi-family connections. A larger diameter lateral may be required based on the
projected wastewater flows from the connection.
• Maintenance holes shall be a minimum of 48 inches in diameter and will be spaced at
intervals ideally at every block as set forth in the City’s Wastewater Engineering
Standards. City blocks are typically 260 feet long. On occasion, maintenance holes may
be spaced at 520 feet subject to City Engineer approval. Only new polyvinyl chloride
(PVC) pipes will be considered for extending the maintenance hole interval.
• Maintenance holes also shall be located at changes in grade, direction, and pipe size,
and at intersections. Maintenance holes located in areas subject to inflow may be
required to include a watertight insert at the request of the Public Works Director.
• New mains connecting to an existing main shall be made via a new or existing
maintenance hole.
CHAPTER 5 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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• The minimum sewer main slope shall be 0.40 feet per 100 feet for 8-inch-diameter
sewer lines. The minimum slope may be reduced if approved by the City Engineer.
Sewers shall have a uniform slope between maintenance holes.
• Testing of the gravity sewer lines and maintenance holes shall be completed in the
presence of the City. Testing shall be performed in accordance with WSDOT/APWA
Standard Specifications Section 7-17.3(2).
Design Flow Rates
• All new gravity sewers shall be designed and constructed to have a minimum velocity of
2 feet per second when flowing full.
• Existing sewers may surcharge up to 1-foot over the crown of the pipe during the peak
hour flow caused by a 20-year, 24-hour storm before requiring replacement. This
criterion shall not apply if this storm produces overflows onto the finished floors of any
customers. New sewers shall be designed to be no more than 75-percent full during the
same storm over the 50-year design life of the main.
• No overflows will be permitted.
• This GSP did not analyze every sub-basin and instead focused on trunkline sewers.
When development occurs within a sub-basin, staff and developers will need to check
the capacity of the sub-basin’s gravity sewer pipes. Slopes in the City generally result in
gravity sewers being steeper than minimum slopes. For reference, an 8 -inch gravity
sewer at 0.4 percent generally will serve 300 single-family units. This is a conservative
rule of thumb to check when developing an infrastructure master plan for the City’s
pre-platted environment and for densification of housing.
Separation Between Sanitary Sewer and Other Utilities
• A minimum horizontal separation of 10 feet and a minimum vertical separation of 3 feet
is required between sewer and domestic water lines (edge to edge).
• The City’s Wastewater Engineering Standards (Appendix G) will be followed, and the
guidelines provided in Ecology’s Criteria for Sewage Works Design should be followed
for difficult spacing or other situations.
Design Period
• The design period is the length of time that a given facility will provide safe, adequate ,
and reliable service. The design period selected is based on the economic life of a given
facility, which is determined by the structural integrity of the facility, the rate of
degradation, the replacement cost, the cost of increasing the capacity of the facility , and
the projected population growth rate serviced by the facility.
• The life expectancy for new sanitary sewers, using current design practices, is in excess
of 50 years.
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Force Main Design Criteria
• All force mains within the City shall be designed in accordance with good engineering
practice by a professional engineer with the minimum design criteria presented in the
Criteria for Sewage Works Design, prepared by Ecology, August 2008, or as superseded
by subsequent updates. Chapter C2 of this document contains design considerations for
force mains.
Low Pressure Sewer Design Criteria
Formalizing the use of low pressure sewer installation is necessary for effective
implementation. The recommended policy and engineering standards for low pressure sewers
should include the following principles:
• Low pressure sewers should only be used where gravity sewers are not reasonabl y
feasible.
• Low pressure sewers should only be used in single-family residential zones where
growth is predictable.
• Low pressure sewers should not be used in multi-family zones.
• Low pressure sewer pumps need to be owned and maintained by the property owners.
The pump system should be of sufficient quality and contain alarms to minimize the
chance of sewer overflow.
• Low pressure laterals are to be privately owned and maintained.
• Low pressure force mains should be designed to City standards and be City owned and
maintained.
• Engineering design standards for low pressure sewer mains should specify durable
materials such as high-density polyethylene (HDPE) pipe, have ample clean out and
flushing ports, and be sized to accommodate entire areas where gravity sewer is not
feasible.
• A master plan of locations where low pressure sewers are allowed should be developed
as incorporated into the Engineering Design Standards.
Side Sewer Design Criteria
• Side sewers shall be constructed in accordance with all applicable City, local, and State
regulations. Refer to the PTMC and the City’s Wastewater Engineering Standards
(Appendix G) for specific criteria.
LIFT STATION POLICIES AND DESIGN CRITERIA
• Lift stations shall be designed in accordance with the City’s most current Wastewater
Engineering Standards and the Ecology’s Criteria for Sewage Works Design.
• Lift stations are expensive to operate and maintain; therefore, their installation should
be limited to locations where gravity is not reasonably feasible only.
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OPERATIONAL POLICIES
Facilities Maintenance
Facility maintenance is performed by the Wastewater and Compost Facility divisions of Public
Works. This includes the maintenance of the WWTF, the Compost Facility, and all lift stations.
• Equipment breakdown is given the highest maintenance priority, and repairs should be
made as soon as possible.
• Equipment should be replaced when it becomes obsolete.
• Worn parts should be repaired, replaced, or rebuilt before they represent a high failure
probability.
• Equipment that is out of service should be returned to service as soon as possible.
• A preventive maintenance schedule shall be established for all facilities, equipment, and
processes.
• Spare parts shall be stocked for all equipment items whose failure will impact the ability
to meet other policy standards.
• Tools shall be obtained and maintained to repair all items whose f ailure will impact the
ability to meet other policy standards.
• Dry, heated shop space should be available to all maintenance personnel to maintain
equipment and store parts.
• Written records and reports will be maintained on each facility and item of equipment
showing its operation and maintenance history.
Collection System Maintenance
The collection system is maintained by the Streets Maintenance and Collections Division of
Public Works.
• At a minimum, all existing gravity mains shall be video inspected every 10 years.
• The target gravity main video inspection interval is 5 years based on the need to
rehabilitate much of the gravity system.
• Gravity mains that experience periodic problems shall be video inspected every 1 to
3 years depending on the documented history of problems.
• Video inspection records will be maintained and incorporated into prioritization of
either pipeline replacement or in-situ rehabilitation.
• Cleaning or jetting of sewer lines shall occur based on video inspection records.
• Root cutting of sewer lines shall be based on video inspection records and historical
sewer blockage trends. Many gravity sewer lines in the City requ ire annual root cutting.
These sewer lines should be prioritized for rehabilitation.
• Many maintenance holes in the collection system are aging past their design life and
experiencing corrosion. Some maintenance holes are still mortared rock or brick.
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Rehabilitation and replacement of maintenance holes on a systematic basis should be
implemented based on inspection records.
Temporary and Emergency Services
• Compliance with construction standards (not water quality standards) may be deferred
for temporary sewer service. Provisions for reliability is necessary for temporary service
to reasonably prevent system failures such as overflows.
• Compliance with all standards may be deferred for emergency sewer service.
• Compliance with all applicable NPDES waste discharge permit requirements must be
met.
Reliabilities
• The City shall invest sufficient resources to ensure that the sewer system is constructed,
operated, and maintained to ensure consistent and reliable service is provided to its
customers.
• Reliability is achieved through investment in rehabilitation or replacement of collection
system components, as well as redundant systems. For example, including back-up
generators for critical lift stations improves reliability.
• The entire WWTF is built with redundant systems to ensure reliable operations. When
redundant systems are compromised or need repair, restoring redundant systems
should be prioritized.
ORGANIZATIONAL POLICIES
Staffing
The sewer treatment and collection systems operate based on the good work of staff.
Therefore, adequate staffing with appropriate training and skills is a key to success. The City
created a skills development program for the Department of Public Works staff to improve skills
and address succession planning. The 2024 budget reflects the addition of a wastewater
treatment apprentice position, as well as restoration of a frozen position in the Streets
Maintenance and Collections Division. The following staffing policies are included in this GSP:
• The sewer utility staffing levels are established by the City Council based on the financial
resources of the City and needs of the sewer utility. Staffing investments are a key
portion of the periodic sewer rate modeling and projections. Staffing, capital
improvements, and required operational costs are to be balanced based on rates set by
City Council.
• The City has three Group II certified wastewater treatment plant operators at the WWTF
and two Group I certified wastewater treatment plant operators at the Compost Facility.
• Staffing must comply with the permit-required certification levels associated with both
treatment facilities. Both the WWTF and the Compost Facility are Group II operator
facilities. The staffing objective is as follows:
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o WWTF – Three certified Group II operators, one of which serves as crew chief for
both the WWTF and the Compost Facility.
o Compost Facility – Two certified Group II operators.
o WWTF and Compost Facility – A shared entry level position serves as an
apprentice to support both facilities’ operations.
o Within the City – Certified electrician capable of working with 480 volt, three-
phase power to serve the City’s Facilities Division, Water Resources Division,
Wastewater Division, and Compost Facility Division of Public Works.
• Personnel certification and training will comply with State-established standards. The
City job descriptions reflect the state certification requirements. The City encourages
and supports training in terms of continuing education and skill development to work in
concert with State certification requirements.
FINANCIAL POLICIES
General
The sewer utility is an enterprise business unit of the City. Enterprise business units by
definition are required to be fiscally sustainable in terms of self -supporting through rates and
charges. Rates and charges need to be analyzed periodically to ensure revenues match
expenses of operations and investment in infrastructure. A balanced approach to establishing
reasonably affordable rates along with the needs of the sewer system to ensure compliance
with public health and safety laws is the focus of periodic rate reviews. The following fiscal
policies help establish this balance. Note, that a number of fiscal assumptions are included in
Chapter 11 with respect to rate setting. The following policies and assumptions in Chapter 11
must align.
• The City will set rates, charges, and fees to maintain sufficient funds to operate,
maintain, and upgrade its sewer system as necessary to provide safe and reliable sewer
service to its customers. These rates will comply with State regulations and be evaluated
in conjunction with the annual budget process to ensure that forecasted expenses and
impacts of regulations are reflected in the rate structure. Typically, rates are established
for a 5-year period and then re-evaluated against actual operational costs and capital
infrastructure needs. The GSP will be reviewed every 5 years and no less than every
10 years. The annual budgeting process refers to the projected expenses included in the
City’s rate model.
• Each developed lot or parcel with active water service (excluding irrigation) is required
to be connected to the City’s sewer system subject to the presence of an existing on-site
septic system permitted by Jefferson County Public Health. Each property shall be
subjected to a monthly sewer charge whether or not such lot or parcel of real property
is actually connected to the sewer system when there is an active domestic water
account. The purpose of this policy is financial sustainability of the sewer system to
ensure that all developed properties pay a base fee whether discharging to the sewer
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system or not. This base fee provides stable funding for the fixed costs incurred by the
City for operating a sewer system for the overall benefit of community public health.
• All new development shall be connected to the sewer system unless meeting the
exemption requirements outlined in PTMC and state law. Note, that per PTMC, all
subdivisions shall be required to provide sewer to all newly created or altered lots
intended for commercial and/or residential development.
• The system development charge (SDC) and all applicable connection fees must be paid
at the time a sewer connection is obtained. SDCs and fees shall be paid prior to issuance
of a final permit approval or prior to occupancy, whichever comes first, accordance with
the City’s Municipal Code.
• The City shall collect sewer extension charges for owners of properties that individually
benefit from publicly built sewer extension facilities, except for those property owners
who previously paid for their fair share of such an extension through a Local
Improvement District (LID) or ULID. This program has not been established and this
policy is recommended to be implemented as a way to create a revolving revenue
source to facilitate sewer extensions. The cost of sewer extensions paid by the City can
be recovered through Local Facility Charges, frontage fees, or LIDs.
• System development charges should be used to offset rate impacts for capital
improvements and not fund debt service.
• Deferral of SDCs should be considered in the setting of system development charge
levels to make sure financial objectives are met. For example, if 10 of 50 new housing
units per year are affordable, SDCs would need to account for a 20-percent decrease in
revenue.
• City Council adopted an income-based discount program. This program should be
monitored over time to evaluate participation levels and impacts on rates. The purpose
of the income-based discount program is to lower the rate impact to community
members burdened by the cost of housing and associated costs.
• If sewer system facilities must be installed or upgraded as a result of a developer’s
impacts, the new facilities or upgrades shall conform to the City’s policies, criteria, and
standards and shall be accomplished at the developer’s expense. The City, however,
shall be responsible for any portion of the costs that are attributable to general facilities ,
such as over-sizing or over-depth requirements, and offer latecomers fees to
developers. Per RCW, the City may participate in developer extension projects and
recover costs associated with the City’s investment from benefited properties. This
practice has not been implemented in the past and is recommended as a future way to
recover costs and contribute to revolving investment in sewer infrastructure extensions.
• If written application for service is approved by the City, the application shall be
considered as a contract in which the applicant agrees to abide by such rates, rules, and
regulations in effect at the time of signing the application or as may be adopted
thereafter by the City and to pay all charges, rates, and fees promptly.
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• In addition to all other user rates and service connection fees required to be paid to the
City, service call fees may apply when made at the request of the owner or occupant of
the premises for assistance in locating and/or repairing a plugged sanitary sewer drain in
accordance with the City’s Municipal Code.
• The City shall manage its income and expenses in a self-supporting manner in
compliance with applicable laws and regulations and its own financial policies.
• The City shall establish a CIP that describes the anticipated improvements or
modifications to the sewer system, planned replacement of aging facilities, upgrades to
existing facilities to provide additional capacity for projected growth, and construction
of general facilities to aid growth. The CIP will be updated at a minimum on a 2-year
basis associated with the requirement of the Growth Management Act and maintaining
a current Capital Facilities Plan.
• The City shall maintain reserves for operations consistent with City reserve policies. The
reserves should consider emergencies, bad debts, existing debt coverage, reserve
requirements, and fluctuations in revenue.
• The City will maintain information systems that provide sufficient financial and statistical
information to ensure conformance with rate-setting policies and objectives.
• Currently, the sewer utility is part of a combined utility with the water utility. It is the
policy of the City to separate these utilities into separate funds to ensure accurate cost
accounting and sustainability of both utilities.
Connection Charges
Connection fees are an important source of revenue for the sewer, water, and stormwater
utilities. The owners of properties that have not been assessed, charged, or borne an equitable
share of the cost of the sewer collection system and WWTF pay connection fees for their
equitable share of connecting to the system. Connection fees help reduce the burden to
existing rate payers. It is noted that some of these charges , such as SDCs for qualifying low
income housing, can be deferred according to PTMC. While connection charges are an
important source of resources for the sewer utility, SDC levels should be evaluated for impacts
on housing and land prices. Higher SDCs combined with other permitting and connection fees
typically drive down the price of land to meet market conditions. However, in some cases, land
prices do not come down, thereby impacting the total cost of housing. The primary challenge
with connection charges for Port Townsend is that much of the City is currently inaccessible to
sewer per state and City codes, and many of the pre-platted rights-of-way do not currently have
sewer pipes within them. Sewer extensions are costly, and the City sewer utility is already
stressed in terms of required upgrades and repairs. Thus, there is a tradeoff between
connections fees and housing affecting rates and financial sustainability. One possible
approach, when legally allowed, is to expand the City deferral program to more housing
options, sizes, and affordability levels or to find additional general fund sources to support
objectives.
The following connection fees are available to the City to assist in sewer utility financial
sustainability. Some of these strategies have been utilized in the past and others have not.
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1. Latecomers Fees (also known as Developer Extension Charges): Latecomers fees are
negotiated with the City, developers, and property owners for the reimbursement of a
pro rata portion of the original costs of sewer system extensions and facilities and are
documented in a Developer Extension Agreement, depending on the application.
Latecomer fees have been the primary tool for developers to obtain partial
reimbursement for their costs of installing or extending sewer mains. Many latecomer s
have been filed with the City in the last 20 years. Latecomer reimbursements are due for
any new connections to sewer in which an agreement is in place for a period of
20 years.
2. Local Facilities Charges: If applicable, Local Facilities Charges may be due based on
established fees by ordinance for specific facilities benefiting specific properties. Pursue
the use of Local Facilities Charges for specific system infrastructure, such as trunkline
extensions, trunkline upsizing, and lift stations. Local Facilities Charges should be used in
areas where new connections are expected. Local Facilities Charges have not been used
historically in the City.
3. Frontage Charges: If applicable, Frontage Charges may be due to reimburse the City for
investment of sewer pipelines benefiting undeveloped properties. Frontage Charges
have not been used historically in the City.
4. LID Assessments: If applicable, these assessments are often paid at the time of
connection as required by lending institutions. These assessments take priority lien
status right behind taxes. LIDs can be implemented by City Council Resolution or by
petition of property owners. LIDs have not been used historically in the City.
5. SDCs: Connection charges shall be assessed against any property connecting to the
sewer system. This charge is for the major facilities that deliver the sewage to the
WWTF and for the facilities to treat and dispose of the sewage. This charge reimburses
customers who have paid for the facilities described and for building capacity to
accommodate growth.
6. Outstanding charges resulting from account delinquency.
This GSP recommends the City develop a connection policy reflecting its housing objectives.
Examples include the following strategies as detailed previously.
• The City developed an issue paper (white paper) in 2023 suggesting expanding the
deferral program for SDCs to housing that is affordable and households earning as much
as 200 percent of the Area Median Income. Further study is necessary to determine the
appropriate affordability level to ensure gifting of publ ic funds prohibitions are not
violated. The intent of this issue paper is to address the inability for many households to
obtain housing, including workforce, fixed income, and other situations that result in
incomes that cannot afford housing in the City.
• Set SDC levels tied to household size, such as those adopted by Oak Harbor. This
recognizes that a small house has less impact on the sewer system than a large house.
• Port Angeles set up a program to reduce fees for middle housing.
• A deferral program or SDC tied to infill housing would recognize the benefit of new
housing and rate payers connecting to the system where infrastructure already exists.
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• Consider developing a front footage connection fee for all pipes installed by the City to
develop a revolving fund for the installation of sewers.
• Using LIDs for new sewer extensions can be a useful tool that captures all benefited
properties. This is especially beneficial where there are large unsewered areas of
undeveloped properties or where existing septic systems are experiencing failures. LIDs
could be implemented in a manner to incentivize development of underutilized
property.
Formalization of connection fee policies occurs through City Council adoption of various
connection fee levels or programs.
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6 | SEWER COLLECTION SYSTEM EVALUATION
INTRODUCTION
This chapter presents the analysis of the existing City of Port Townsend (City) wastewater
collection system. Individual sewer system components were analyzed to determine their
ability to meet policies and design criteria under both existing and projected flow conditions.
The policies and design criteria are presented in Chapter 5, and the wastewater system flow
and loading analysis is presented in Chapter 4. A description of the existing wastewater system
facilities and current operation is presented in Chapter 2. A distribution of growth map for the
purpose of hydraulic modeling of trunklines is included in Chapter 3. The capital improvement
projects resulting from the existing and projected flow condition analyses are presented in
Chapter 10.
COLLECTION SYSTEM ANALYSIS
Hydraulic Model
Background
A computer-based hydraulic model of the existing sewer system was created using the
SewerGEMS® program developed by Bentley Systems. The entire sewer collection system was
modeled, including gravity mains, force mains, and sewer lift stations. The hydraulic model was
created using the best information available and data provided by the City. Pipe locations,
lengths, diameters, and materials were added based on the previous hydraulic sewer model,
GIS data, as-built drawings, various system maps, survey information, and information acquired
from the City. Maintenance hole invert and rim elevation data from the City’s GIS and survey
information was used, if available. The remaining elevation data was extracted from Jefferson
County topographic data. Minimum slope and cover values also were used in the development
of the model and are annotated in the data files. The output from this model was used to
evaluate the capacity of the existing collection system and identify improvements that will be
required to handle wastewater flows. The model can be updated and maintained for use as a
tool to aid in future planning. Refer to Appendix I for basic data used to construct the model.
Model Limitations
Due to the number of data gaps and assumptions used in the model, the accuracy of the model
should be confirmed prior to undertaking any replacement or rehabilitation projects, especially
for projects not located along a major trunk sewer. The results of the modeling should be
considered approximate, and additional investigations, such as field surveys, flow monitoring,
and lift station pump down tests, should be performed in the vicinity of any proposed
improvements prior to design and construction. If it is found that the input information differs
significantly from actual conditions, the model should be updated accordingly and rerun to
confirm the original results.
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Modeling was performed using a steady-state analysis, which shows all flows reaching all
downstream points simultaneously. This is conservative and not truly representative of
conditions that occur, since it takes some time for wastewater to travel downstream through
the sewer system, which stores and attenuates peak flows.
Flow Data
Existing and projected flow rates for the sewer drainage basins were developed in Chapter 4.
The total existing flows are shown in Table 4-3, and the projected total system flows are shown
in Table 4-10 in Chapter 4. Table 4-11 in Chapter 4 details existing average annual flow and
peak hour flow (PHF) for each sewer lift station. As discussed in Chapter 4, the City’s projected
wastewater flow by basin was estimated from population growth per basin as provided by City
planning staff (Figure 3-3) and calculated from peaking factors and per capita flows as
estimated in Chapter 4. The total existing and projected flows by basin are shown in Table 4-12
in Chapter 4. It is recommended that the City obtain additional flow data from the sewer
drainage basins to accurately evaluate capacity in areas with suspected deficiencies for future
planning and design.
Facilities
The hydraulic model of the existing system contains all active existing system facilities.
Available information for the lift stations, such as pump capacity, total dynamic head,
horsepower, wet well diameter, wet well depth, and force main diameter, is included in the
model. For simplicity, the existing lift stations were modeled as having variable frequency drives
(VFDs) on the pumps so that they discharge at the same rate as the influent flow rate regardless
of head conditions.
Hydraulic Analyses Results
Hydraulic analyses were performed based on the existing flow rates (2018), as well as projected
flow rates for 2028, 2033, and 2043. In the evaluation, the criteria for listing an existing sewer
pipe as deficient is that the upstream maintenance hole is surcharged more than 1 foot during
the estimated PHF. The results for the 2028, 2033, and 2043 modeling are included in
Appendix I.
Pipe Capacity Deficiencies
It is intended that this General Sewer Plan (GSP) contain an inclusive list of recommended
system improvements; however, additional projects may need to be added or removed from
the list as growth occurs or conditions change. The City will evaluate the capacity of the
wastewater collection system as growth occurs and development applications are received.
Existing System
Currently, the existing gravity sewers do not have deficient conveyance capacity. That is, no
maintenance hole surcharges over 1 foot above the crown of the pipe during existing peak
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flows. This was observed in the model and confirmed by the City’s operations staff. Surcharging
only occurs at the discharge of the Monroe Street Lift Station force main to the gravity sewer
on Water Street. Design of a new and larger Water Street gravity sewer main to receive the
flow is underway; therefore, it is not included in the Capital Improvement Plan (CIP) in
Chapter 10.
Future Analyses
The primary driver of gravity main capacity improvements for the 5 -year, 6- to 10-year, and
11- to 20-year planning periods are the projected flows from the proposed development of the
Mill site. Fortunately, this flow will be conveyed by gravity to the wastewater treatment facility
(WWTF) following discharge from the proposed Mill Lift Station force main. Existing lift stations
will not be taxed by these additional flows; however, substantial investment in the upsizing of
existing pipelines will be required over the next 20 years to convey these flows to the WWTF.
The following sections provide a summary of gravity conveyance deficiencies for the 5-, 10-,
and 20-year design horizons. The colors of the mains to be upsized are red, green, and blue,
respectively, for the 5-, 10-, and 20-year scenarios presented here and in Chapter 10.
5-Year Forecast Hydraulic Deficiencies
Figure 6-1 shows CIP SM1. These pipelines are estimated to be hydraulically deficient within the
next 5 years after the construction of the Mill Lift Station. The pipelines, shown in red, may
need their alignment shifted from existing to get more distance from existing structures.
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Figure 6-1 – CIP SM1
6- to 10-Year Forecast
The growth of the Mill site will warrant upsizing the gravity pipelines shown in green in
Figures 6-2 and 6-3 by the year 2033.
CIP SM1 must be upgraded simultaneously with the construction of the Mill Lift Station.
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Figure 6-2 – CIP SM2
Figure 6-3 – CIPs SM3 and SM4
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11- to 20-Year Forecast
Sewer mains shown in blue in Figures 6-4 through 6-6 are anticipated to need upgrades by
2043 to be able to convey anticipated flows without causing the pipelines to flow more than
75-percent full.
Figure 6-4 – CIP SM5
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Figure 6-5 – CIP SM6
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Figure 6-6 – CIP SM7
Other Existing Gravity Collection System Deficiencies
The City does not have complete knowledge about the condition of its collection system
because of antiquated and broken video inspection equipment. During the attempted
inspection of the Water Street gravity main in 2023, a contracted video inspection company
recorded mains suspected of being structurally deficient. The results of these inspections were
alarming, as some pipelines contained earthen sediments (Water Street) and others were
cracked, crushed, and becoming oval in cross-section (Washington Street; Figures 6-7 and 6-8).
Only a small sampling of the City’s collection system was inspected and significant structural
defects were found. It is imperative that the City begin a systematic inspection plan with a goal
of viewing the interior of all pipes and maintenance holes within the next 5 to 10 years. As
these inspections are performed, pipe materials should be noted and recorded in the City’s GIS
system to improve system records. Many pipelines are of unknown material, making pipe
lifespan predictions difficult. Gaining knowledge about the existing collection system will allow
the City to identify those mains that are most urgently in need of repair or replacement and will
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help prevent occurrences like the collapse of the Water Street gravity sewer on
December 27, 2022. The City’s ability to maintain and update the collection system will be
greatly aided by recording pipe materials and conditions and storing this information in the GIS
system it has established. Purchase of modern inspection equipment and committing
employees to the inspection of pipelines will yield savings and prevent future wastewater
overflows.
Figure 6-7 – CIP SM10
Figure 6-8 – Washington Street Sewer with Cracks
This section of pipe in Washington Street is in danger of imminent collapse.
Longitudinal cracks and deformation in Washington Street sewer portend collapse.
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LIFT STATION ANALYSIS
Lift Station Capacity
Existing System
The hydraulic analysis of the City’s existing lift stations (Table 4-12) shows that only the Monroe
Street Lift Station does not have adequate capacity. As discussed previously, capacity analyses
of each lift station are based on estimated PHF. According to discussions with the system
operators, there are no known capacity deficiencies in the City’s existing lift stations during
current operating conditions except for the Monroe Street Lift Station. These deficiencies are
discussed later in this chapter.
2028, 2033, and 2043 Lift Station Needs
Only modest population growth is forecast within the current City limits and it is dispersed
throughout the City as shown in Figure 3-3. Of this growth, less than 20 percent is forecast to
occur in the existing lift station basins. The remainder will flow by gravity to the WWTF. There
will be small, incremental increases to each existing lift station over the next 20 years, leaving
the total flow to be pumped by each station below each their firm capacities. None of the
existing lift stations are forecast to have capacity shortfalls, except for the Monroe Street Lift
Station. The station handling most of the new growth will be the proposed Mill Lift Station.
Predesign studies show that a 1,062 gallons per minute (gpm) capacity is required. Refer to
Appendix J for an estimation of the flows for this lift station. Capacity upgrades are needed for
the Mill and Monroe Street Lift Stations.
Monroe Street Lift Station
The Monroe Street Lift Station is currently under capacity and regularly has all three of the
station’s pumps operating to convey peak flows. The station has not overflowed, but it is the
City’s standard to have two pumps with one redundant pump to accommodate PHFs. For this
reason, the capacity must be increased, or the peak flow tributary to the station must be
reduced. As part of the Water Street Sewer Replacement project, scheduled for 2024, new
pump impellers will be installed for each of the station’s pumps. The existing electric motors
have spare capacity to accommodate larger impellers that could deliver approximately 100 gpm
more from the station. However, this will not be enough to bring the lift station into compliance
with desired capacity standards. RH2 Engineering, Inc., (RH2) recommends that inflow in the
basin draining to the lift station be reduced to decrease the load on the lift station.
Lawrence Street, between Fillmore and Monroe Streets, has stormwater inlets connecting to
the gravity sewer (Figure 6-9). This is a likely cause for the Monroe Street Lift Station’s
overload. This inflow also taxes the capacity of the WWTF unnecessarily with stormwater.
Separation of the storm and sanitary sewer could possibly reduce the hydraulic loads entering
the Monroe Street Lift Station. Smoke testing and video inspection of the sewer main in
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Lawrence Street should be performed to locate the connections between the storm and
sanitary sewer systems.
Figure 6-9 – CIP SM9
In addition to capacity shortfalls, the Monroe Street Lift Station is aging and near the shoreline,
placing it at risk for flooding due to forecasted sea level rise. The City of Port Townsend Sea
Level Rise and Coastal Flooding Risk Assessment (City of Port Townsend & Cascadia Consulting
Group, 2022) (Appendix K) lists the Monroe Street Lift Station as a public facility at risk of
flooding with the potential for “high consequence.” The lift station access hatches must be
elevated or the lift station must be relocated to higher ground. All pumps, pipes, valves,
electrical panels, and controls must be replaced with new units to increase the reliability of this
vital lift station. Flow measurement also should be added to the station to assist the City in
quantifying the inflow tributary to the lift station.
Hydraulically, the lift station’s force main is performing well and appears to be in good
condition. It is approaching 60 years in age, and record drawings show that it is cast iron pipe.
When the existing 10-inch cast iron force main is exposed for any reason, the exterior should be
inspected for pitting and corrosion. Cast iron pipe from the 1960s came with cement mortar
lining, and the main could still be in good condition. Out of caution, the City should monitor the
discharge pressure characteristics of the lift station closely. Sudden decreases in pressure could
indicate a breach in the pipe. Increases show occlusion of the pipeline due to corrosion or
The sanitary and storm sewers in Lawrence Street must be separated to reduce hydraulic
loads on wastewater facilities.
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sediment deposition. The City should take all opportunities to observe the main’s exterior for
deterioration since exterior corrosion of the iron main is a risk in the marine environment.
Work to separate the Lawrence Street storm and sanitary sewers should be completed prior to
designing improvements for the Monroe Street Lift Station. This will allow the pumps to be
sized appropriately if inflow is substantially reduced. RH2 suspects that PHF could drop
dramatically with the storm inlets removed from the sanitary sewer. This may be adequate to
provide a temporary solution to the Monroe Street Lift Station’s capacity problem. This
temporary solution may allow the full lift station rehabilitation or relocation to be delayed by
5 to 10 years.
Other Lift Station Improvements
A budget will be set aside in the CIP for minor repairs and replacements of pump motors, pump
impellers, telemetry unit replacement, valve overhauls, panel replacements, generator
replacements, force main repairs, and other minor improvements to keep the existing lift
stations operating reliably. The City has two existing major lift stations: Monroe Street and
Gaines Street. Gaines Street was upgraded in 2021, and Monroe Street will be scheduled for
upgrades as discussed previously. The Mill site will add another major lift station within the
next 2 to 3 years. All major lift stations will be relatively new and/or rehabilitated in the 2020s,
and no additional capacity or significant upgrades will be needed during the 20-year planning
horizon. The remaining lift stations are small with minor replacement needs. The CIP will
include a general allowance to cover these needs.
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7 | EXISTING TREATMENT FACILITIES ASSESSMENT
BACKGROUND
History and Introduction
The City of Port Townsend’s (City) original wastewater treatment facility (WWTF) was constructed
in 1967 to receive wastewater from approximately 90 percent of the City’s sewer services and to
provide primary treatment and disinfection with chlorine gas. The WWTF was expanded in 1993 to
provide full secondary treatment. This expansion included a new Headworks facility, oxidation
ditches, secondary clarifiers, chlorine contact basins, conversion of the original plant primary
treatment tanks to aerobic sludge holding tanks, a Control building, and electrical and supervisory
control and data acquisition (SCADA) system improvements.
The City’s Compost Facility is located at the Jefferson County Landfill and receives dewatered
biosolids from the WWTF, as well as dewatered septage from Jefferson County (County), yard
waste from the City and County, and other wood wastes. Liquids generated from these processes,
including septage filtrate, contaminated stormwater runoff, and compost aeration condensate, are
treated in a separate wastewater treatment facility consisting of a sequencing batch reactor (SBR)
with disinfection and effluent disposal to constructed wetlands followed by discharge to infiltration
basins for ultimate disposal.
This chapter presents the evaluations of the existing WWTF and Compost Facility conditions,
including the existing liquid stream and solids handling processes. It also presents an evaluation of
the electrical and SCADA systems. Deficiencies identified from the evaluations are described, and
recommendations for capital improvements are summarized. The analyses of needed
improvements to the treatment facilities for water quality and capacity are provided in Chapter 8.
All WWTF capital improvements are identified in Chapter 10.
System Overview
Wastewater from the City’s collection system is conveyed to the WWTF and flows via gravity to the
Influent Pump Station located on the WWTF site. Wastewater from the Influent Pump Station,
which also includes facility-generated wastewater and process drains, is pumped to the inlet of the
Headworks. From the Headworks, wastewater enters the oxidation ditches, secondary clarifiers,
and chlorine contact basins before heading to the Strait of Juan de Fuca through an outfall
structure. Waste sludge is captured in the aerobic sludge holding tanks and pumped to the belt
press, and dewatered solids are hauled off to the City’s Compost Facility. An important
consideration in a wastewater treatment system is that virtually all of the system components must
have redundant or back-up components. For example, the plant must be able to run with one
clarifier out of service. Thus, upgrades to a system also require upgrades to the redundant
components. This adds to the cost of upgrades significantly but is a requirement to ensure that the
plant operates reliably.
The approximate locations of major WWTF process units are outlined in Figure 7-1 and shown
schematically in Figure 7-2.
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Figure 7-1 – Existing WWTF Overall Site Plan
Figure 7-2 – Existing WWTF Process Schematic
Historical WWTF Performance
The historical performance of the WWTF from 2019 through 2022 is compared to the City’s
National Pollutant Discharge Elimination System (NPDES) Permit limits as shown in Table 7-1.
Influent Pump Station Oxidation Ditches
Control
Building
Non-Potable Water Pumps
Headworks
Secondary
Clarifier No. 1
Secondary
Clarifier No. 2
Chlorine Contact Basins
Aerobic
Holding Tanks
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Table 7-1
WWTF Performance Based on NPDES Permit Effluent Limits (2019-2022)
As shown in the table, the City has maintained compliance with its NPDES Permit limits and no
exceedances of the permit were reported for the last 4 years. As required by the NPDES Permit, the
City also monitors priority nutrients, priority pollutants, and other parameters and undergoes
whole effluent toxicity testing in the winter and summer of the final year of each permit cycle.
None of these items have prompted additional activities or permit actions in recent years. The
WWTF is well maintained and earned the Washington State Department of Ecology’s Outstanding
Performance Award for the 25th consecutive year in 2022.
As noted in Chapter 2, the City also is subject to the Puget Sound Nu trient General Permit (PSNGP).
Starting in February 2022, the City was required to monitor and report nitrogen compounds on its
Discharge Monitoring Reports. Table 7-2 is a summary of the monthly sampling results for 2022.
Table 7-2
Monthly Nitrogen Sampling Results
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The average annual Total Inorganic Nitrogen (TIN) is well below 10 milligrams per liter (mg/L). Only
two samples exceeded 10 mg/L in the sampling period.
WWTF EXISTING PROCESS UNITS EVALUATION
Introduction
The WWTF secondary treatment expansion in 1993 was the last major improvement or expansion
to the facility. This section provides a review of the general conditions of each major process or
area within the WWTF. The analyses and findings provided herein were based on observation of
visible areas around the WWTF, discussions with City operations and maintenance staff, and a
2019 Condition Assessment Summary Report performed by Jacobs (Appendix L).
Although most equipment and processes continue to function satisfactorily and meet existing
demands, several of these systems are nearing the end of their design life and need to be replaced
or upgraded. In general, these include major improvements to the Influent Pump Station,
Headworks, secondary clarifiers, oxidation ditches, and electrical and SCADA systems. Other minor
improvements that were previously noted are also described in this chapter.
Overall, the visible elements of the WWTF generally appear to be in good physical condition except
where noted otherwise. The age of the equipment and processes is one of the main drivers for the
WWTF improvements, and details are provided in the subsequent sections.
Influent Pump Station
Overview
The City’s collection system includes two influent gravity sewer mains that enter the Influent Pump
Station (IPS), which is located near the center of the WWTF site. The IPS also receives various
WWTF process drains.
The IPS consists of a below-grade, cast-in-place concrete structure that houses 3 submersible
influent pumps, each with a nominal capacity of 2,250 gallons per minute. Each of the three pumps
have below-grade check valve systems outside of the wet well. Downstream of the check valve
systems, the discharge piping from the pumps combines to a common force main that directs flow
up to the elevated Headworks channels.
Under normal operating conditions, one pump operates as the lead pump , a second lag pump turns
on during extreme flow events, and the third pump serves as a redundant pump. The pumps are
cycled weekly to avoid overuse of any single pump and to prolong the service life of all three
pumps.
Condition Assessment
IPS Structure
The existing IPS structure was constructed as part of the 1993 secondary treatment expansion
project. The interior liner is detaching from the concrete and portions of the cast-in-place concrete
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walls and ceiling are corroding. There is notable exposed aggregate and the surfaces need to be
rehabilitated in the near term to prolong the useful life of this structure.
IPS Mechanical
The original submersible pumps from the 1993 WWTF secondary treatment expansion project
experienced corrosion and were replaced after the expansion with Flygt N-style impeller pumps.
Since then, minimal corrosion has been noted and no major repairs have been necessary for the
Flygt pumps. The stainless steel pump guide rails are generally in satisfactory condition with only
minor corrosion. Due to the IPS needing to remain in operation, the pump discharge piping and
fittings were not able to be observed. However, due to the age and condition of the IPS
infrastructure, it is recommended to further evaluate this system during other improvement work
in the IPS and prioritize replacing mechanical components if determined necessary.
Major Electrical and Control Equipment
Major improvements to the IPS electrical and control equipment are expected during the planning
period due to significant corrosion and aging infrastructure. The junction boxes, conduits, and level
instrumentation directly inside the IPS, as well as the power raceways and variable frequency
drives (VFDs) from the electrical room need to be replaced in the near term. Additionally, one of
the electrical conduits has corroded to the point where one of the pumps is now out of service. In
an emergency, this pump can be brought back into service by a quick pump wiring change;
however, this is an example of the urgency needed to rebuild th e IPS. The power and control cables
of the pumps are connected to plugs located near the top of the IPS. These plugs are accessible and
should be maintained to allow WWTF staff to efficiently disconnect and remove pumps from the
IPS if needed.
Summary of Major Findings
Based on the conditions assessment, a summary of the recommendations for major improvements
to the IPS is as follows:
1. Rehabilitate the concrete infrastructure inside the IPS wet well. Coat the interior walls and
ceiling for future corrosion protection.
2. Evaluate the condition of the mechanical equipment in the IPS and replace it if necessary.
3. Replace the electrical equipment associated with the IPS, including raceways, VFDs, and
instrumentation.
Headworks
Overview
The Headworks building was constructed as part of the 1993 WWTF secondary treatment
expansion project to include a mechanical bar screen in the covered concrete influent channel. In
approximately 2009, the original screen was replaced with a new automatic Parkson Aqua Guard
mechanical bar screen that has a 66-inch nominal width. The IPS discharges raw water into the
influent channel through the bar screen. Screenings are dewatered in a compactor system that
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discharges to the screenings and grit hopper in the Headworks building before being disposed
offsite. A bypass channel is adjacent to the main influent channel and houses a manual bar screen
that can be isolated with stop gates.
Screened influent enters the original Smith and Loveless Pistagrit vortex-style grit removal chamber
located on the northern side of the Headworks building. The grit chamber is 10 feet in diameter
and is nominally rated at 7 million gallons per day. Screened influent also can be diverted to bypass
the grit chamber if necessary. De-gritted influent from the grit chamber flows through a
1-foot-wide Parshall flume in a separate concrete channel and combines with return activated
sludge (RAS) at the end of the Headworks before entering the oxidation ditches. The settled grit
slurry in the grit removal chamber is directed to the grit classifier, which dewaters and washes the
grit, before being discharged to the screenings and grit hopper and disposed offsite. The grit
classifier was replaced around 2009 and is located on the main level of the Headworks building.
The Headworks screen and grit removal system is an important part of the plant operation.
However, failures in the system do not disrupt plant operation. The result of a Headworks
equipment failure is that grit is transferred to the oxidation ditches, which creates the need for
additional cleaning. Careful maintenance and inspection of the equipment, maximizing the life of
the equipment, can extend when equipment replacement would be needed. There is budget
provided in the Capital Improvement Plan (CIP) for replacement if needed. However, given the
Headworks ultimately will be replaced, if staff can extend the life of this equipment to the time of
the Headworks building replacement, savings in the overall CIP will be realized.
Condition Assessment
Headworks Influent Channels Structure
The influent channels are cast-in-place concrete. These structures appear to be in satisfactory
condition, requiring only some rehabilitation work relating to the interior liner system. The
embedded liner was not adequately installed on a concrete support column in the RAS return basin
and is peeling away at the corners of the column. Liner failure also was observed previously near
the temporary gates. Significant liner failures exist over the RAS and influent splitter weirs and
under the cover of the influent wet well, which will need to be improved. Concrete corrosion has
been noted previously at the bottom of the Parshall flume; however, the Parshall flume and
associated instrumentation appear to provide accurate influent flow readings.
Mechanical Screens
The mechanical screen appears to be functioning well with minimal corrosion observed. Other
components, including channel covers and gates, appear to be in good condition. Near the screen,
a short section of ductile iron non-potable water pipe was previously observed to be uncoated and
moderately corroded where there was no thermal insulation.
Grit Removal Chamber and Grit Room
The original vortex grit unit appears to be functioning well with minor wearing that are not
uncommon or of concern. However, the grit unit was not dewatered and out of service during the
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site visit, so submerged components could not be reviewed. No significant grit accumulation
downstream of the grit unit has been reported. The air lift tube and cyclone have been rebuilt
previously due to the original units wearing out and appear to be in good condition. The screenings
compactor and compactor tube have been noted to be in good condition ; overall, no corrosion
issues have been observed in the grit room.
Summary of Major Findings
Based on the conditions assessment, a summary of the recommendations for major improvements
to the Headworks is as follows:
1. Repair the embedded plastic liner on the concrete columns and walls in the Headworks
influent channels. These improvements should be included with the IPS concrete liner
system improvements as previously discussed. These improvements should occur in the
near term and more details are included in Chapter 10 (CIP F1).
2. Due to the age of infrastructure, it is recommended to plan for the replacement of the
screen and grit removal equipment within the next 5 to 10 years. More details are included
in Chapter 10.
Summary of Minor Findings
Based on the conditions assessment, a summary of the recommendations for minor improvements
to the Headworks is as follows:
1. Repair and coat the ductile iron non-potable water pipe near the mechanical screen.
2. Perform minor repairs to Headworks equipment to extend its life until the Headworks
building is replaced.
Activated Sludge System
Overview
Prior to the addition of secondary treatment to the WWTF, the facility provided treatment utilizing
two primary treatment tanks and chlorine disinfection. During the secondary treatment
improvements in 1993, the activated sludge system was added to the WWTF and included two
oxidation ditches and two secondary clarifiers. The existing primary treatment tanks were
converted into aerobic sludge holding tanks. The current activated sludge system is a suspended
growth system that utilizes microorganisms in the liquid of the oxidation ditches to provide
biological treatment of the wastewater. The oxidation ditches and secondary clarifiers were
configured within the hydraulic profile such that influent could flow by gravity from the Headworks
to the oxidation ditches, the secondary clarifiers, and then the chlorine contact basin before
reaching the outfall. Each of the activated sludge components is discussed in greater detail as
follows.
Oxidation Ditches
The oxidation ditches are where biological treatment occurs. This system utilizes a combination of
mixing wastewater and oxygen to break down organics. The ditches also are operated such that a
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small anaerobic zone provides some nitrogen removal. Wastewater from the Headworks and RAS
processes combine and flow to the two oxidation ditches using isolation gates. The oxidation
ditches are original Eimco Carrousel Systems, each with a nominal volume of 0.57 million gallons.
Each ditch contains a deck-mounted vertical paddle mixer/aerator that supplies dissolved oxygen
into the ditch. These mixer/aerators operate on a two-speed mode, high and low, and each utilizes
a 75-horsepower motor. The gearbox assemblies for the mixer shafts are housed in noise enclosure
structures on top of the ditches. The mixed liquor enters the oxidation ditches, flows around the
Carrousel system, and exits over adjustable weirs to downstream processes.
Secondary Clarifiers and Processes
Clarifiers serve the purpose of separating solids from water after the biological treatment has
occurred in the oxidation ditches. After exiting the oxidation ditches, the mixed liquor is split
between two 50-foot-diameter Eimco secondary clarifiers. The two secondary clarifiers are circular
concrete tanks that are identical in size and construction. The secondary clarifier mechanisms are
original, each operating on a 0.75-horsepower drive motor. Each clarifier mechanism directs settled
mixed liquor to three RAS pumps that return to the splitter box downstream of the Headworks
Parshall flume. Each mechanism also collects floatable items (referred to herein as scum) and
directs the collected material to a scum box in each clarifier. An existing scum pump conveys scum
to the aerobic holding tanks. Settled sludge from the clarifiers also is pumped to the aerobic
holding tanks using two waste activated sludge (WAS) pumps. Clarified effluent exits over the
clarifier weirs and discharges to the chlorine contact basins.
Chlorine Contact Basins
Prior to discharge to the Strait of Juan de Fuca, treated water must be disinfected. The current
system utilizes a chlorination system approach to disinfection. The clarified effluent from the
secondary clarifiers enters the chlorine contact basins and is disinfected with chlorine,
dechlorinated with sodium bisulfite, and finally discharged through the outfall of the WWTF. The
two chlorine contact chamber structures are original, and two feed pumps are used to dose liquid
sodium hypochlorite into the clarified effluent. The original fiberglass reinforced plastic (FRP) tank
holding the hypochlorite was previously replaced with a 6,200-gallon high density polyethylene
(HDPE) tank. Once dosed with hypochlorite, the effluent flows through a serpentine path
throughout the chlorine contact basins to meet contact time requirements. The effluent is then
dechlorinated with liquid sodium bisulfite before being discharged through the outfall. The sodium
bisulfite is held in a 1,100-gallon tank manufactured by Chemical Proof Corporation. Two Peabody
Floway non-potable water pumps at the end of the chlorine contact basins supply part of the
effluent back throughout the plant for various processes. Scum also is collected near the end of
these basins and pumped to the aerobic holding tanks.
Condition Assessment
Oxidation Ditches
The visible concrete of the oxidation ditches generally appeared to be in good condition; however,
submerged concrete was not observed due to both ditches remaining in operation. The
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mixer/aerators appear to be in good condition with minimal vibration and both gearbox enclosures
appear to be sufficiently ventilated. The paddle of one mixer/aerator was replaced previously and
there is a spare motor available. Further assessment of the ditches is provided in Chapter 8.
Secondary Clarifiers and Processes
The original clarifier mechanisms appear to be in satisfactory condition and the original drives and
motors are still in service. These items have been in service for over 30 years now, and have
reached their expected design life. However, with careful monitoring and maintenance, the design
life can be extended. Minor corrosion has been noted on the mechanism in areas with coating
defects that have become noticeable over time; however, no major mechanical or capacity issues
have previously been noted. The original carbon steel fasteners on the mechanisms were replaced
previously with stainless steel hardware due to past failures, and other carbon steel support
brackets have been previously observed to be corroding. Minimal corrosion issues have been noted
on the concrete floor inside the secondary clarifiers, with only minor leaching and exposed
aggregate observed in the clarifier launders. The steel walkway, FRP weirs, and baffles of the
clarifiers all appear to be in sufficient condition.
There have been no major concerns with the WAS/RAS station between the two secondary
clarifiers as the piping and appurtenances are in a good overall condition. Only minor replacement
and maintenance work has been required in the past. No major capacity, functionality, or
conditions-based issues have been observed for the RAS, WAS, and scum systems.
Chlorine Contact Basins
Overall, the chlorine contact basins are in satisfactory condition with only a few issues noted. The
gate operator stems have been observed to be corroding at the water surface and a few wood
planks above the water are rotting. The conditions of the planks below water have not been
observed. No major capacity, functionality, or conditions-based issues were observed with these
basins. No corrosion issues have been noted for the sodium hypochlorite or sodium bisulfite
systems, and no issues have been noted on the HDPE hypochlorite storage tank. The City has
observed previously that the existing non-potable water pumps have corrosion issues.
Discharge Outfall
The existing discharge outfall into the Strait of Juan de Fuca was not evaluated as part of this
General Sewer Plan (GSP). The City is separately actively working with the Washington State
Department of Ecology (Ecology) and Jacobs on the outfall replacement/upgrade, and that work
was in progress at the time of this GSP. Further discussion is contained within Chapter 8.
Summary of Major Findings
Based on the conditions assessment, a summary of the recommendations for major improvements
to the activated sludge system is as follows.
Oxidation Ditches
Chapter 8 discusses operational modifications to maintain nutrient reduction within the existing
system capacity and improve actual treatment capacity. Ultimately, the oxidation ditches will have
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to be replaced with larger ditches to address increasing demands on the system and nutrient
removal. Interim improvements will be needed for nutrient removal. The evaluation in Chapter 8
provides the recommended next steps for improvements on the oxidation ditches ; more details are
provided in Chapters 8 and 10.
Secondary Clarifiers and Processes
Clarifier upgrades are included in the CIP. The clarifiers need to be maintained as they are not
planned to be replaced in the next 20 years. Extending the life of the clarifiers provides significant
savings over the long term.
1. Re-coat the concrete launders of both secondary clarifiers.
2. The existing mechanisms of both secondary clarifiers are at or nearing the end of their
design life. Continue to monitor mechanisms annually and at manufacturer recommended
frequency on drive units and consider oil testing as recommended by the manufacturer.
Plan to replace the mechanisms and replace or rehabilitate the drive units.
Chlorine Contact Basins
Continued maintenance of the chlorine contact basins is recommended as these facilities are not
planned to be replaced in the next 20 years.
1. Replace the non-potable water pumps in-kind and associated electrical equipment in the
near term.
Summary of Minor Findings
Based on the conditions assessment, a summary of the recommendations for minor improvements
to the activated sludge system is as follows.
Secondary Clarifiers and Processes
1. Replace the carbon steel weir support brackets with stainless steel brackets in the near
term.
2. Re-coat areas of the mechanisms that have notable spot corrosion.
Chlorine Contact Basins
1. Repair or replace gate operator stems with notable corrosion.
2. Evaluate the condition of all wood planks associated with the chlorine contact basins and
repair or replace components as necessary.
Sludge Holding, Dewatering, and Disposal
Overview
The WAS pumped from the secondary clarifiers enters the aerobic holding tanks that provide
sludge storage prior to dewatering. The sludge in these holding tanks is aerated to stay mixed and
aerobic. Rotary lobe blowers located in the lower level of the Control building supply the air into
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the holding tanks. Decanting is required to thicken the sludge before it is pumped to the belt filter
press for dewatering. This process is facilitated by the addition of polymer solution into the feed
sludge for enhanced dewatering. The dewatered sludge produced from the WWTF is loaded onto a
sludge hauling truck via a shaftless screw conveyor and delivered offsite to the City’s Compost
Facility.
Condition Assessment
No major capacity or conditions-based issues have been observed in either the aerobic holding
tanks or the blower room. The rotary lobe blowers have been noted to be in good overall condition
with adequate capacity. Some coarse bubble diffusers also have been previously noted to be
missing. The aerobic holding tanks were converted from the original primary treatment tanks and a
thorough evaluation is recommended to evaluate the structural integrity of the infrastructur e.
The belt press is original and appears to be in good condition with no significant corrosion. The belt
press room is well ventilated with only minor corrosion previously noted at the entrance steel door
base frame and on light fixture metal housings. The aluminum platforms and grating are in good
condition, but the grout under the aluminum column bases has deteriorated. No issues have been
noted with the shaftless screw conveyor for sludge disposal.
Summary of Major Findings
Based on the conditions assessment, a summary of the recommendations for major improvements
to the sludge holding system is as follows:
1. Due to aging infrastructure, it is recommended to plan for upgrades to the solids handling
equipment, including the existing rotary lobe blowers, WAS pumps, and belt press unit
within the next 5 to 10 years. More details are provided in Chapter 8.
2. Evaluate the structural integrity of the aerobic holding tanks and plan for repairs within the
next 5 to 10 years. More details are provided in Chapter 8.
Summary of Minor Findings
Based on the conditions assessment, a summary of the recommendations for minor improvements
to the sludge holding system is as follows:
1. Identify coarse bubble diffusers that are potentially missing and replace as needed.
2. Repair the grout under the aluminum column bases in the belt filter press room.
3. Repair minor corrosion within the belt filter press room as needed.
Odor Control System
Overview
The odor control system focuses on removing foul air from the most od oriferous locations in the
treatment process, including the IPS, Headworks, and grit and screenings holding room. The
original odor control system directs air from the Headworks influent channel, influent wet well, and
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grit room to a carbon scrubber vessel located outside and adjacent to the Headworks building. The
odor control fan for pulling this air is located adjacent to the carbon scrubber vessel.
Condition Assessment
As described previously, severe corrosion and degradation of the concrete liner within the
Headworks has been noted, indicating the potential build-up of sulfuric gases. Historically, there
have been infrequent off-site odor complaints, indicating there may be sufficient air exchange to
contain odors but not enough to reduce sulfuric gas formation on contact surfaces. Spot
penetrations have been noted along the ducting from the Headworks to the carbon vessel, which
could be a result of internal corrosion. The carbon scrubber vessel that holds activated carbon
appears to be in good physical condition.
Summary of Major Findings
Based on the conditions assessment, a summary of the recommendations for major improvements
to the odor control system is as follows:
1. Upgrade the odor control fan and activated carbon system to increase treatment capacity.
2. Replace the odor control ducting from the top of the Headworks to the carbon scrubber
vessel.
Electrical and SCADA Existing Systems Evaluation
Electrical Components
Overview
Wastewater treatment plants are highly dependent on electricity. Electrical systems, including
back-up power, deserve critical attention to avoid system failures. The existing electrical service
and distribution equipment dates back to the 1993 WWTF expan sion and upgrades. Electrical utility
service is supplied to the facility by Jefferson County Public Utility District (PUD) from a PUD-owned
1,000 kilovolt-amperes pad-mounted transformer. The secondary electrical service to the facility is
a 1,600 Amperes (A) service with the main service disconnect located within Motor Control Center
(MCC) No. 1. MCC No. 1 resides in the ground level of the Headworks building. Located within MCC
No. 1 are feeder circuit breakers that feed power to other MCCs located throughout the WWTF.
MCC No. 1 feeds power to MCC No. 1X, which also is located on the ground level of the Headworks
building, MCC No. 2 is located in the RAS/WAS pump station, MCC No. 3 is located in the Control
building, and MCC No. 4 is located at the digesters. The MCCs are used to distribute power to all
motors and equipment throughout the facility. Critical electrical loads and equipment that require
backup power are supplied from MCC No. 1X. MCC No. 1X includes a 600 A automatic transfer
switch (ATS) for automatically switching to backup power in the event of a power failure. A
475 kilowatt standby diesel generator, manufactured by Caterpillar, is located in the ground level
of the Headworks building. This generator is connected to the ATS in MCC No. 1X and supplies
backup power to all the electrical loads and equipment powered out of MCC No. 1X. The existing
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MCC equipment throughout the facility is manufactured by Cutler -Hammer/Eaton and are Unitrol
model MCCs.
Some of the motors throughout the facility utilize variable frequency drives (VFDs) for modulating
motor speed. These motors include the influent pumps, RAS pumps, and the belt press feed pump.
The VFDs are manufactured by Reliance Electric.
Condition Assessment
• The existing MCC equipment looks to be well maintained and in good condition considering
the age of the equipment. This equipment is approximately 30 years old and is nearing the
end of its expected lifespan. The typical lifespan for similar electrical equipment is
approximately 25 to 40 years. One of the issues with maintaining older equipment is
locating replacement parts when equipment fails. Fortunately for the City, Eaton has robust
aftermarket support and is still able to support replacement of components for the Unitrol
model MCC. However, that may not be the case for long. It is estimated that this equipment
has approximately 5 to 10 years of life remaining.
• The City’s existing VFDs, manufactured by Reliance Electric, are no longer supported and are
obsolete. Reliance Electric was purchased by Rockwell Automation in 1996, and Rockwell
Automation no longer supports these drives. Replacement of all seven VFDs at the WWTF is
recommended.
• An Arc Flash Analysis has not been performed for the existing electrical distribution system,
which is required by the National Electrical Code (NEC) for services of this size. It is
recommended that a plantwide electrical short circuit, protective device coordination, and
arc flash analysis be completed soon. These studies need to be completed to be in
compliance with the NEC and need to be updated every 5 years.
• The standby generator, while also nearing the end of its expected 25- to 40-year lifespan,
looks to have been maintained well and is in good working condition. Similar to the MCC
equipment, it is estimated that this equipment has approximately 5 to 10 years of life
remaining.
• Significant corrosion was observed on the conduits and conduit supports inside the IPS.
Replacement of the conduits, supports, conductors, and cables inside the IPS is
recommended.
• Some corrosion and rust were observed throughout the WWTF on various enclosures,
flexible conduits, and fittings. It is recommended to remove this rust where able to do so
and add rust protectant coating to extend the life of these components. Full replacement
may be needed in some areas if corrosion is severe enough.
Summary of Major Findings
Based on the conditions assessment, a summary of the recommendations for major improvements
to the electrical system is as follows:
1. Plan for MCC and standby generator replacement within the next 5 to 10 years.
2. Budget for near-term replacement of all seven VFDs.
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3. Perform a short circuit, protective device coordination, and arc flash analysis on the
electrical distribution system.
4. Replace conduits, supports, conductors, and cables inside the IPS.
5. Address electrical enclosure and conduit corrosion as needed throughout the WWTF.
Central SCADA System
Overview
The SCADA system is the computer and electronic control element of the plant. SCADA allows for
automation of system processes and monitoring and is the system that enables plant operators to
control physical processes within the plant. The central components of the SCADA system and
instruments are from the 1993 WWTF upgrades. The existing SCADA system consists of three
control panels located throughout the facility that are interconnected via a DH+ serial
communication protocol. A SCADA human machine interface (HMI) computer located at the WWTF
allows the City to monitor and control the system. The HMI computer was last upgraded around
2017. The three control panels include the Main Control Panel, CP-3, which is located in the Control
building. The other two control panels are considered Remote Input/Output (I/O) panels as they do
not contain a central processing unit (CPU) and instead allow for an I/O extension to the Main
Control Panel. The first Remote I/O panel, CP-1, is located on the ground level of the Headworks
building. The second Remote I/O panel, CP-2, is located in the RAS/WAS pump station.
Condition Assessment
• All three control panels are equipped with obsolete Allen-Bradley PLC-5 programmable logic
controller (PLC) equipment. These were considered obsolete by Allen-Bradley in 2011, so
parts are difficult and expensive to obtain. Replacement of these components with
Allen-Bradley ControlLogix PLC equipment is recommended.
• The SCADA HMI computer does not require major additional upgrades at this time. The
computer hardware should be replaced within the next 5 years . The typical lifespan of
SCADA computer hardware is 5 to 10 years. The Factory Talk View SE software currently
installed can be reinstalled on the new hardware.
• Uninterruptible power supply (UPS) equipment located within each of the control panels is
well maintained but has exceeded its useful expected life. Replacement of the UPS
equipment is recommended.
• PLC and UPS replacements should occur as soon as possible.
• The communication network infrastructure is using an outdated serial network platform.
The new PLC CPUs require Ethernet-based communications instead of serial
communication. Replacement of the existing serial communication network with an
Ethernet-based network is required when the PLCs are updated. This network can be either
a copper-based Ethernet network or a fiber optic based Ethernet network. A fiber optic
network is recommended as it is not subject to electrical interference or lightning, it can be
installed at longer distances, and it will provide the City with a higher speed network.
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• The Parshall flume flow meter transmitter (FIT-460) has issues with the LCD display. The
original manufacturer, Magnetrol, no longer supports replacements, so this meter should
be replaced as soon as possible.
• The instruments inside the IPS are corroded and need to be replaced. The gas transmitter
inside the wet well is extremely corroded and there is no reading on the panel meter, which
indicates failure.
• Many instruments have been abandoned in place, including:
o Network radio antenna;
o Milltronics MultiRanger Plus transmitter (previously used for hypochlorite tank level
measurement); and
o De-energized Dechlor controller (Strantrol 190-300).
Summary of Major Findings
Based on the conditions assessment, a SCADA system overhaul is recommended in the near term. A
summary of the recommendations for major improvements to the central SCADA system is as
follows:
• Replace existing LE and LIT-210 wet well level instruments with a single-sealed unit, equal to
VegaPLUS WL61.
• Replace existing LSH and LSL-210 wet well low-level and high-level float switches with new
switches, Intrinsic Safety Barriers, and 316L SST mounting pole.
• Replace existing AE and AIT-240 wet well explosive gas sensor instruments with a new
remote sensor that draws and returns samples to the wet well.
• Replace all conduit inside the wet well and under buried conditions with handhole access
and sealed transitions to protect all cables.
• Replace obsolete Allen-Bradley PLC-5 system with ControlLogix PLC equipment.
• Replace Serial Remote I/O network with Ethernet Device Level Ring network. Fiber optic
cable is recommended.
• Replace existing UPSs at the three control panels.
• Replace the Parshall flume flow meter with a new FIT-460.
• Plan for replacement of the SCADA HMI computer hardware.
COMPOST FACILITY EXISTING SYSTEMS EVALUATION
Overview
The City’s Compost Facility is located at the Jefferson County Transfer Station Site and handles yard
waste and septage accepted from both the County and the City. The dewatered sludge generated
from the WWTF also is delivered to this facility. The compost mixtures incorporate dewatered
biosolids and yard waste to produce compost piles that are aerated. The compost is transferred
with a front-end loader to be cured before it is screened and prepared for distribution in
conformance with Ecology requirements.
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The septage received at the Compost Facility is screened in a septage screening vault and held in
two steel, aerated 10,000-gallon tanks. The septage is then dewatered and the filtrate from this
process, as well as all other liquid waste streams around the facility, drain to a sequencing batch
reactor (SBR) for treatment. Dewatered sludge feeds into the facility’s compost mixing process as
previously discussed. The SBR is approximately 42,000 gallons and consists of a submerged turbine
aerator, methanol feed pump, WAS pump, and supernatant pump station. The WAS from the SBR is
pumped back to the septage screening vault, while the supernatant is disinfected with sodium
hypochlorite and discharged to constructed wetlands for further treatment. The constructed
wetlands are made up of two cells, each with an area of approximately 6,500 square feet , that have
a combined approximate maximum detention time of 17 total days. The treated effluent from
these wetlands enters a flow control structure and discharges to the infiltration basins for final
disposal.
Odors resulting from the septage holding tanks and compost aeration syst em are treated with
biofilter media. This media consists of finished compost, soil and/or wood chips, and ground yard
waste, and it is monitored for temperature, moisture content, and pH for process control and
operation. A fan provides air pressure to discharge odorous air through the biofilter media evenly.
Figure 7-3 shows the approximate locations of the major Compost Facility processes , and
Figure 7-4 shows the general process schematic of the Compost Facility.
Figure 7-3 – Existing Compost Facility Overall Site Plan
SBR Disposal
System
SBR and Related
Treatment System
Composting Area
Composting
Barns
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Figure 7-4 – Existing Compost Facility Process Schematic
Condition Assessment
Solids Handling Influent System
Septage haulers manually rake the bar screen and wash down the septage receiving area and
screening vault. From the initial screening, septage is sent to one of two holding tanks. A significant
amount of grit has been noted in one of the t wo 10,000-gallon septage holding tanks such that only
the other tank is usable and is limiting the overall holding capacity. Grit is difficult to remove from
these tanks. A new holding tank with a larger capacity should be installed, along with associated
blowers to provide aeration into the holding tank. The influent system should be automated by
installing a new packaged septage screening and grit removal system with an influent meter to
monitor flow.
Septage Treatment System
The existing SBR appeared to be in good physical condition and continues to provide sufficient
treatment. However, the blowers, pumps, and other associated equipment are aging and should be
considered for replacement in the future.
Compost Facility Infrastructure
Due to the age of infrastructure and equipment, the composting screen, front-end loader, and
aeration blowers associated with the composting process are nearing the end of their useful life
and should be replaced. The concrete supports of the compost pole building have notable
deterioration and need to be refurbished. Around the facility, the asphalt has degraded and should
be repaired. In the existing pole building, the lighting is insufficient. Adequate accommodations and
sufficient on-site fire flow capacity should be available to operational staff who will be present
regularly.
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Summary of Major Findings
Based on the conditions assessment, a summary of the recommendations for major improvements
to the Compost Facility is as follows. Refer to the Proposed CIP Implementation Schedule in
Chapter 10 for the timeframes of the recommendations.
Solids Handling Influent System
1. Install an automated, packaged septage screening and grit removal system.
2. Install an influent meter to monitor flow.
Septage Treatment System
1. Remove the two existing septage holding tanks and install a new larger septage holding
tank.
2. Install new aeration blowers for the new septage holding tank.
3. Replace aging SBR equipment.
4. Replace the WAS, chlorination, and wetland disposal pumps.
Compost Facility Infrastructure
1. Replace the composting screen.
2. Replace the composting front-end loader.
3. Replace the composting aeration blowers.
4. Refurbish the compost holding bay concrete supports.
5. Repair and seal asphalt around the facility.
6. Install new lighting inside the existing pole building.
7. Install a new hydrant connected to the water main feeding the facility.
8. Construct a new office for staffing accommodation s.
TREATMENT FACILITIES ASSESSMENT CONCLUSION
This chapter described the recommended major and minor improvements for the City’s WWTF and
Compost Facility based on an evaluation of existing conditions. Given the major capital
improvements and impacts on City operations, the next three chapters provide a basis for a capital
improvement plan. Alternatives analyses for major capital improvements are presented in
Chapter 8, and the recommended capital improvement projects are identified and further detailed
in Chapter 10. The City’s operations and maintenance program is presented in Chapter 9.
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8 | TREATMENT FACILITIES ANALYSIS
INTRODUCTION
The future regulatory requirements for the wastewater treatment facility (WWTF) are outlined in
Chapter 2 of this General Sewer Plan (GSP). Chapter 4 projects growth of the influent flow and
loading. Chapter 7 evaluates the condition of the existing facilities. In addition to these items, this
chapter evaluates the ability of the City of Port Townsend’s (City) WWTF to reliably meet the
requirements of its National Pollutant Discharge Elimination System (NPDES) Permit through the
planning period given the major considerations presented in previous chapters. This chapter
analyzes alternatives to meet the needs of the WWTF through the planning period and provides
recommendations for improvements.
MAJOR CONSIDERATIONS FOR WWTF IMPROVEMENTS
Based on the analyses of the previous chapters, the major factors influencing the WWTF planning
are:
• Growth;
• Future regulations, specifically nitrogen removal requirements;
• Footprint constraints of the WWTF;
• Age and condition of the existing facility components.
Each factor is briefly introduced in the following sections.
Growth in Flow and Loading
The existing and projected flow and loading is defined in Chapter 4. The projected values are
summarized in Table 8-1, along with the current rated capacity of the WWTF per the NPDES Permit.
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Table 8-1
Projected Influent Flow and Loading
As shown in the table, the projected 2043 flow and biochemical oxygen demand (BOD) loading is
very near to the permitted capacity of the WWTF. Further, the projected 2033 BOD loading exceeds
85 percent of the rated capacity. The City’s NPDES Permit requires the City to begin planning for an
expansion of facility capacity when flow and loading exceeds 85 percent of the permitted maximum
month value for 3 consecutive months. It takes considerable time (up to 10 years) to properly plan
for and permit major treatment plant expansion, and as such, it is recommended that the City
begin planning for such an expansion in the first 5 years of the planning period.
Regulatory Changes – Nitrogen Reduction
As discussed in Chapter 2, the future regulations that will most significantly influence WWTF
planning are the nitrogen limits proposed by the Puget Sound Nutrient General Permit (PSNGP),
which became effective in 2022. The City is considered to be in the category of “WWTFs with small
[Total Inorganic Nitrogen] TIN loads” by the PSNGP. As detailed in Chapter 2, the PSNGP requires
dischargers in this category to:
• Develop and implement a Nitrogen Optimization Plan (NOP). The general intent of the NOP
is to assess and recommend optimization strategies to maximize TIN removal at the existing
WWTF primarily through operational changes, minor on-site improvements, and off-site
source control. The dischargers were required to select an initial optimization strategy by
December 31, 2022. The NOP should analyze and document the performance of the
selected optimization strategy. The NOP must be submitted by March 31, 2026; and
• Complete an all known available and reasonable methods of prevention, control, and
treatment (AKART) analysis that evaluates reasonable treatment alternatives that will
maintain the WWTF annual average effluent TIN below 10 milligrams per liter (mg/L). This
analysis must include wastewater characterization, analysis of treatment technologies,
Parameter Existing 2033 2043 Buildout
NPDES
Permit
Rating
85% of
Permit
Rating
Annual Average Daily Flow 0.87 1.19 1.46 2.39 1.44 1.22
Maximum Month Daily Flow 1.16 1.59 1.94 3.19 2.05 1.74
Maximum Day Flow 1.82 3.38 4.12 6.77 --
Peak Hour Flow 3.06 4.91 6.06 9.82 --
Annual Average Daily BOD 2,591 3,202 3,706 5,819 3,754 3,191
Maximum Month Daily BOD 2,718 3,546 4,105 6,445 --
Annual Average Daily TSS 2,493 3,125 3,630 5,742 4,568 3,883
Maximum Month Daily TSS 2,799 3,470 4,030 6,376 --
Green shaded cells exceed 85% of the rated capacity and orange shaded cells exceed 100% of rated capacity.
TSS = total suspended solids
Hydraulic Loading (MGD)
BOD Loading (ppd)
TSS Loading (ppd)
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economic evaluation, environmental justice review, recommendation of the most
reasonable treatment alternative, and an implementation schedule. The AKART analysis
must be submitted by December 31, 2025. Notably, the PSNGP states that “permittees that
maintain an annual TIN average of < 10 mg/L and do not document an increase in load
through their [Discharge Monitoring Reports] DMRs do not have to submit this analysis.”
• Meet additional monitoring and record retention requirements as discussed in Chapter 2.
For the purposes of this GSP, an annual average effluent TIN below 10 mg/L is considered the
benchmark for analyzing alternatives for improvements to the WWTF. The existing WWTF was not
designed with a dedicated denitrification process, which would be necessary to reliably provide TIN
reduction at the permitted flow and loading conditions. Upgrading the WWTF to provide TIN
reduction at the permitted flow and loading would necessitate a major reconfiguration of the
facility.
It is understood that continued modeling by the Washington State Department of Ecology (Ecology)
or other factors may change the structure of the final TIN limit. It should be noted that the final TIN
limit may be different from an annual average of 10 mg/L for the City, and as such, it is likely in the
City’s best interest to extend the useful life of the existing WWTF infrastructure and defer the need
to make major improvements until the future effluent nitrogen limits have been finalized. As
discussed in the Activated Sludge System section, the City is currently utilizing an optimization
strategy to meet a TIN limit of 10 mg/L. This chapter discusses improvements of limited mechanical
and structural scope that could be made to allow the TIN limit to continue to be reliably met for at
least a portion of the planning period.
It should be noted that if regulatory conditions result in more stringent limits, the timeline for
planning improvements may be accelerated and capital costs increased, which would require either
significant grant resources and/or larger rate increases.
WWTF Site Footprint
One of the major factors influencing WWTF planning is the constrained nature of the existing
WWTF site. The site is bounded to the east by the body of water referred to as the Chinese
Gardens. To the west, the site is bounded by Kuhn Street. Figure 8-1 shows the existing site aerial
with parcel lines and ownership, as well as the surrounding areas.
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Figure 8-1 – WWTF and Surrounding Parcels
The WWTF occupies two parcels transected by platted right-of-way (ROW) extending from
53rd Street. The City owns an additional parcel to the south of the WWTF that contains a single
structure (house converted to an office). This parcel is separated from the WWTF parcels by
platted, vacant ROW. Similarly, a platted strip of vacant ROW lies immediately north of the
northmost WWTF parcel. To the north and south beyond are private parcels.
The platted and vacant ROW section north and south of the WWTF parcel must be maintained for
public access to the waterfront per Revised Code of Washington (RCW) 35.79.035. This area
potentially could be used for below-grade utilities, but it is not prudent to plan any above-grade
tankage and infrastructure in these areas.
Figure 8-2 shows the current WWTF and parcels.
Figure 8-2 – WWTF Site Aerial
On Figure 8-2, there are three general spaces within the existing WWTF footprint that are not
occupied with permanent, above-grade WWTF infrastructure:
• The northeast corner of the site, north of the existing sludge holding tanks, is vacant and
could be utilized. However, this area is relatively small and is isolated from the main
process piping and interconnections. This space may be used for ancillary improvements.
However, this space does not readily facilitate any significant expansion of the WWTF ;
Port Townsend
WWTF
Parcel owned
by City
Vacant ROW
Kuhn St.
53
rd
St
.
Kuhn St.
N
N
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• The southmost parcel, which contains one existing building, could potentially be
repurposed for expansion of the WWTF. However, as previously stated, the southern
section of unused ROW cannot be used for permanent, above-grade infrastructure. As
such, this parcel will remain somewhat isolated from the main WWTF infrastructure.
Relative to the size of the existing WWTF, the parcel is also relatively small and could
support only limited new infrastructure. Similar to the northeast corner of the WWTF, this
parcel does not readily facilitate any significant expansion of the WWTF; and
• The paved area north of the oxidation ditches is relatively small and encumbered by
significant below-grade utilities. The area also is used for parking and vehicle access. This
area does not readily facilitate any significant expansion of the WWTF.
In general, the existing WWTF infrastructure occupies most of the area included in the City parcels
and there is not sufficient available space on these parcels to plan for a major expansion of the
WWTF.
Age and Condition
Chapter 7 summarized the existing conditions of the major unit processes and areas of the WWTF.
The facility has been exceptionally well maintained. However, the last major improvements to the
facility were made over 30 years ago and numerous improvements will be needed during the
planning period due to the age of the infrastructure. It is known that major changes to the facility
will be needed during the planning period to meet new regulations and growth. The
recommendations in this chapter seek to avoid unnecessarily investing in the rehabilitation of aging
items that are likely to be substantially reconfigured or replaced later in the planning period. The
intent is to make improvements that maintain the operability and reliability of the WWTF and
extend its useful life while avoiding major sunk costs for such improvements.
Due to its size, the concrete oxidation ditch tankage is the largest and most valuable asset at the
WWTF. Understanding the remaining useful life of this tankage is critical in analyzing the activated
sludge system improvements. As noted in Chapter 7, the existing oxidation ditch concrete appears
to be in good physical condition. However, these tanks were designed over 30 years ago and will be
over 50 years of age at the end of the planning period. Further, the tankage was not designed to
current codes and may not meet current requirements for seismic conditions, as an example. As
discussed in the Activated Sludge System section, major improvements will be needed later in the
planning period to expand facility capacity while meeting nitrogen reduction requirements. Some
options for these improvements include reuse of the existing oxidation ditch tankage. It should be
noted that any significant reconfiguration of the oxidation ditches will require substantial structural
modifications to meet current codes. This likely will be very costly and may not be prudent given
the advanced age of the structure at the time of the improvements. This factor warrants significant
consideration when analyzing activated sludge system improvements in the subsequent sections of
this chapter.
APPROACH TO WWTF ANALYSES
Improvements to the activated sludge system (oxidation ditches and clarifiers) are needed for
nitrogen reduction and to expand WWTF capacity. These improvements are expected to have the
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largest impact on WWTF planning; therefore, the major WWTF processes are reviewed in the
following order:
1. Activated sludge system.
2. Preliminary treatment system.
3. Effluent disinfection system.
4. Solids handling system.
ACTIVATED SLUDGE SYSTEM
Existing Activated Sludge System
Original Design Criteria
The existing activated sludge system consists of two oxidation ditches and two secondary clarifiers.
Each ditch contains a single two-speed mechanical surface aerator (referred to herein as
mixer/aerators). The design criteria for the oxidation ditches is included in Table 8-2 from the
original construction drawings.
Table 8-2
Original Oxidation Ditch Design Criteria
Oxidation Ditches Quantity
Aeration Basin 2
Volume, Each (MG)0.57
MLSS (mg/L)2,800
MLVSS (mg/L)2,100
Hydraulic Retention Time (hrs)
Average Annual Design 22
Maximum Month Design 15
Maximum Day Design 9
Solids Retention Time (Days)
Average Day 15
F/M
Average 0.10
Maximum Month 0.14
Oxygen Required (lb/hr)
Average 100
Maximum Day 340
Surface Aerators, 2 Speed 2
Size, Each (hp)75
MG = million gallons
MLVSS = mixed liquor volatile suspended solids
lb/hr = pounds per hour
hp = horsepower
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The original design criteria shown in Table 8-2 assumes two basins are online. At the average
annual condition, with a solids retention time (SRT) of 15 days, the predicted mixed liquor
suspended solids (MLSS) concentration is 2,800 mg/L with two basins online. The original design
loading for the WWTF is included in Table 8-3.
Table 8-3
Original Facility Design Flow and Load
It should be noted that the 20-year design values (2013 values) shown in the table are slightly
below the currently permitted values shown in Table 8-1. For the purposes of this chapter, the
permitted values generally are used for the subsequent analyses.
Capacity Analysis
The ability to settle the biological floc of an activated sludge system in the secondary clarifiers
typically constrains the capacity of the system. The solids loading rate (SLR) to the clarifiers
represents the allowable solids load per unit of clarifier operating surface area. The typical
secondary clarifier SLR design criteria is an average of 25 pounds per square foot per day (lb/sf/d)
and a peak SLR of 40 lb/sf/d for conventional activated sludge . As the microbial population
increases in the oxidation ditches (represented by the MLSS concentration), clarifier SLR generally
increases proportionally. As SRT increases, so does the MLSS concentration due to the extended
time available for microbial growth. As such, the SRT and MLSS are both indirectly limited by the
settleability of the activated sludge. The existing WWTF includes two 50-foot diameter secondary
clarifiers. Table 8-4 shows the calculated SLR for operating scenarios with one or two clarifiers
online. This table assumes both oxidation ditches are online and the MLSS is constant at 2,800 mg/L
for all conditions.
YR 1993 YR 2013
Average Annual (AAF)0.96 1.27
Maximum Month (MMF)1.33 1.81
Maximum Day (MDF)2.34 2.92
Peak Hour (PHF)4.35 5.27
Average Day 1,444 2,054
Maximum Month 2,055 2,804
Maximum Day 3,846 5,346
Average Day 1,444 2,054
Maximum Month 2,158 3,018
Maximum Day 5,121 7,102
WWTF Influent - Design Loadings and Flow Rates
Design Flow Rates (MGD)
Design BOD Loadings (ppd)
Design TSS Loadings (ppd)
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Table 8-4
Predicted Clarifier SLR for Existing Activated Sludge System at MLSS 2,800 mg/L
As shown in the table, at the original maximum month design condition of 1.81 million gallons per
day (MGD), as well as at the permitted maximum month condition of 2.05 MGD, the clarifier SLR is
below the recommended range with two oxidation ditches and two clarifiers in service. However, if
one clarifier is out of service, as must be considered for normal maintenance or a failure, the SLR
will exceed the recommended range. Although not shown in the table, a similar result would be
expected if one oxidation ditch is out of service with two clarifiers online.
Due to the existing constraints presented in the WWTF Site Footprint section, there appears to be
no simple method to add a third clarifier to the site, which would otherwise alleviate the potential
single clarifier condition. The third clarifier would most practically be located immediately adjacent
to the existing clarifiers to facilitate the large and complex pipe connections. This is not feasible
with the current oxidation ditches and parcel boundaries.
As shown in this analysis, the clarifier SLR effectively limits the WWTF capacity approximately at the
current WWTP rating. Further, there is no readily available location to add a third clarifier on the
site to alleviate this capacity restraint.
Current Strategy for Nitrogen Reduction
The original activated sludge system was designed and expected to produce fully nitrified effluent
(ammonia converted to nitrate). At the design loading with the existing aerators at full speed, there
should be sufficient oxygen transfer and SRT to allow for full nitrification. However, in this
configuration, minimal denitrification is likely to occur, which is necessary to convert nitrate to
nitrogen gas to reduce overall nitrogen in the effluent. At the time the WWTF was designed,
denitrification was not a consideration. For denitrification to occur, an anoxic environment must be
provided in the system. No dedicated anoxic environment was provided in the oxidation ditches as
originally configured. The oxidation ditches each consist of an entirely aerated, closed loop reactor
as shown in Figure 8-3.
One Clarifier Two Clarifiers
Condition MM Influent
Flow (MGD)
SLR
(lb/sf/d)
SLR
(lb/sf/d)
Design Average Annual 1.27 23 11
Design Maximum Month 1.81 32 16
Permitted Maximum Month 2.05 37 18
RAS rate at 50% of the influent flow rate per design criteria.
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Figure 8-3 – Existing Oxidation Ditch Configuration
Note: Single ditch shown.
The result of this configuration is minimal TIN reduction in the effluent. Further, nitrification
consumes alkalinity and without denitrification it can be difficult to maintain effluent pH within
NPDES Permit limits without supplementing alkalinity to the process.
As previously noted, the WWTF is required to implement and monitor an optimization strategy to
reduce effluent TIN as required by the PSNGP. When operated as designed, the aerators provide
sufficient oxygen to maintain adequate dissolved oxygen (DO) concentration throughout the
entirety of the reactor. As an optimization strategy, the operators are currently operating the
aerator for each ditch in low speed. By doing this, the oxygen transfer is limited, which allows for
the creation of an anoxic area that is low or devoid of oxygen on the downstream end of the
reactor loop. This configuration is similar to that described in Table 8-24, row (o) of Wastewater
Engineering: Treatment and Resource Recovery, 5th edition (2013, Metcalf & Eddy). Figure 8-4
illustrates this configuration.
Figure 8-4 – Current Operation of Existing Oxidation Ditch with Aerator at Low Speed
Note: Single ditch shown.
This approach has generally allowed the operators to reliably maintain effluent TIN below 10 mg/L
at the current flow and loading conditions. However, this approach has several drawbacks, which
are discussed as follows:
• Reduction in capacity: By limiting the aerators to low speed, the capacity of the oxidation
ditches is effectively reduced. The oxidation ditch design criteria (Table 8-2) assumed that
the aerators are operating at a high speed to provide peak oxygen transfer. Maintaining the
aerators at a low speed, to create the anoxic zone, reduces the capacity of the system to
oxidize influent constituents and significantly reduces the design capacity for BOD removal.
Currently, the influent is below the design BOD load, but with growth, it is expected t hat the
aerators will need to run at high speed more consistently to meet BOD demand. Without a
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dedicated anoxic zone, the entire ditch volume is expected to be aerobic with the aerators
in high speed and TIN reduction will not substantially occur.
• Anoxic zone variability: Currently, there is no automation that would control the
mixer/aerator speed between low and high speed based on loading conditions and the
resulting DO demand. As such, the aerators are operated manually and predominately in
low speed. With the normal diurnal variability in loading and subsequent DO utilization, the
size of the anoxic zone may vary significantly and is generally uncontrolled. This issue will be
exacerbated as flow and loading increases and will make reliably meeting the permit limits
more challenging.
• Anoxic zone location: In the current optimization strategy, the anoxic zone is inherently at
the downstream end of the reactor. Typically, activated sludge systems designed for
nitrogen removal include anoxic zones upstream of oxic zones such that some influent
carbon can be used by organisms to perform denitrification. This configuration allows for
efficient use of carbon and a higher rate of denitrification. The current optimization strategy
does not allow for this approach.
• Filamentous Organism Growth: Filamentous organisms can reduce the settleability of
activated sludge significantly, which, as previously discussed, restrains the capacity of
activated sludge systems. These organisms can thrive in low DO environments and should
be a significant concern with the current optimization strategy, which inherently creates
areas of low DO. The WWTF’s current sludge volume index values, which measure the
settleability of the activated sludge, tend to be in the range of 150 to 250. These values
generally are considered to be indicative of relatively poor settling sludge. This issue will be
of further concern with growth in flow and loading.
The current optimization strategy is reducing effluent TIN substantially and has been implemented
without incurring capital expenditures. The City’s operators are effectively managing the system to
reliably produce TIN below 10 mg/L. While this approach has been valuable to the City in meeting
the initial PSNGP requirements, for the reasons previously stated, it is not recommended that this
strategy be relied upon for more than approximately the next 5 years (2028).
It is in the best City’s interest to maintain TIN reduction going forward. The current optimization
strategy should continue to be utilized , but more permanent improvements should be prioritized in
the next 5 years. Given this, the remaining analyses of this chapter review improvements of limited
scope that can be made soon to continue to provide TIN reduction, extend the useful life of the
activated sludge system, and allow for deferral of significant improvements to the WWTF.
Screening of Nitrogen Treatment Options
Nitrogen is reduced via biological treatment of wastewater through aerobic activated sludge
treatment as discussed previously. Aerobic activated sludge systems have been utilized for this
purpose in a variety of configurations. To support nitrogen reduction, each process seeks to
provide nitrification though an aerobic system and denitrification through an environment low in,
or devoid of, dissolved oxygen. There are two general categories of activated sludge systems:
suspended growth and attached growth. Within these categories and subcategories, many
variations exist.
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Suspended Growth Processes
Suspended growth processes are detailed in Chapter 8 of Metcalf & Eddy (2013) and generally
include the basic subcategories for each system as listed.
• Complete-mix systems – Large, single stage tanks with substantial mixing/recirculation
equipment to dilute influent into the tank and avoid short circuiting.
o The existing oxidation ditch system is an extended aeration system that constitutes a
special type of complete-mix system. An oxidation ditch is completely mixed due to
the high rate of recycle but also contains of single point of aeration that creates an
oxygen gradient along the flow path of the reactor.
• Plug flow, staged systems – Typically consist of long, narrow basins with multiple zones.
• Sequencing batch reactors (SBRs) – Consist of two or more tanks to which batches of
influent are cycled for treatment.
Of the three general subcategories of suspended growth processes, complete -mix and plug flow,
staged systems are applicable for analysis at this site as discussed further in this chapter. Improving
the existing oxidation ditch system is reviewed first in the Improvements to Existing Oxidation
Ditch System section. Implementing a plug flow, staged system would constitute complete
replacement of the existing activated sludge system and is evaluated in the Replacement of the
Existing Oxidation System section.
SBRs are not considered practical to implement at the existing WWTF site as they represent an
entirely new process configuration with new tankage. As previously established in the WWTF Site
Footprint section, there is not sufficient available space on the site to maintain the operation of the
existing system while adding the new tankage that would be necessary for an SBR system.
Attached Growth Processes
Attached growth processes are detailed in Chapter 9 of Metcalf & Eddy (2013) and generally
include the basic subcategories for each system as listed.
• Standard biofilm processes – Various configurations in which flow passes through either
stationary or moving carriers to which biofilm is attached.
• Integrated biofilm and activated sludge processes – Various configurations in which either
stationary or moving biofilm carriers are utilized with suspended growth activated sludge to
provide treatment.
Similar to SBRs, most standard biofilm processes are not practical for consideration at the existing
site. However, one standard biofilm process and three integrated processes are screened for
applicability in this section. These systems typically are promoted as supplemental equipment
options intended to represent minimally invasive improvements to existing activated sludge
systems and include the following.
• Integrated biofilm and activated sludge processes
o Integrated fixed film activated sludge (IFAS)
o Membrane aerated biofilm reactors (MABR)
o Mobile organic biofilm (MOB)
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• Standard biofilm processes
o Denitrification filters for tertiary treatment
Attached Growth – IFAS
IFAS is a biological treatment that integrates suspended growth activated sludge with fixed film
growth. IFAS adds inert carriers, typically plastic, to the activated sludge system to facilitate fixed
film growth. A screen retains the carriers in the reactors while suspended growth is carried through
the normal flow path to the secondary clarifiers and returned by the return activated sludge (RAS)
or wasted. Multiple manufacturers provide IFAS systems, with many proven installations. The
typically stated benefits of this system include:
• Biomass density can be increased through the addition of fixed film organisms without
proportionally increasing the secondary clarifier SLR;
• Simultaneous nitrification and denitrification can potentially occur within the biofilm;
however, there is not enough information to verify that this can reliably be achieved at all
operating conditions;
• Nitrification and denitrification can be achieved at SRTs lower than conventional flocculant
sludge;
• The likelihood of microbial washout at high flows is decreased due to the retention of the
fixed film organisms; and
• Reduced yield of waste sludge.
However, IFAS is not considered compatible with a closed loop oxidation ditch system and surface
aerators. Floor-mounted diffused aeration is necessary to ensure that the media remains
adequately suspended throughout the reactor. Further, multiple partitioned zones would be
necessary to ensure that the media remains evenly distributed along the length of the reactor .
These requirements would incur a high capital cost and would be difficult to implement. Further,
the system likely would only incrementally increase the overall capacity of the activated sludge
system. This option is not considered further.
Attached Growth – MABR
MABR is biological treatment that integrates suspended growth activated sludge with fixed film
growth. In this system, cassettes of membranes are installed into one or more zones of an
activated sludge system. The membrane cassettes are similar to those used in membrane
bioreactor systems; however, with MABR, the membranes are used as both a fixed biofilm carrier
and an aeration device. The membranes are stationary in the tank and biofilm attaches to the
surface of the membranes. The membranes are used to transfer oxygen directly to the biofilm.
Suspended growth activated sludge develops in the bulk liquid, is passed to subsequent zone s, and
is returned from the secondary clarifiers. The MABR process has been characterized in Ecology’s
Criteria for Sewage Works Design as a new and developmental technology as defined in Section
G1-5.4.1.
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The typically stated benefits of MABR include:
• Biomass density can be increased through the addition of fixed film organisms without
proportionally increasing the clarifier SLR;
• The total system oxygen transfer efficiency is increased as a portion of the total oxygen is
delivered through the membranes directly to the biomass in lieu of passing through the
bulk liquid;
• Simultaneous nitrification and denitrification potentially can occur within the biofilm, but
there is not enough information to verify that this can be achieved reliably at all operating
conditions;
• Nitrification and denitrification can be achieved at SRTs lower than conventional flocculant
sludge;
• The likelihood of microbial washout at high flows is decreased due to the retention of the
fixed film organisms; and
• Reduced yield of waste sludge.
The primary difficulty with implementing MABR into the existing WWTF is that MABR cassettes
typically are installed within the initial partitioned zone of a plug flow system. It is unlikely that
MABR could be integrated into a closed loop oxidation ditch system. Implementing this system
would require many of the same elements as IFAS; therefore, this option is not considered further.
Attached Growth – MOB
MOB is a biological treatment process intended to enhance suspended growth activated sludge
systems. Nuvoda is currently the only company known to sell such systems. The MOB process
consists of adding small organic carriers to an activated sludge system to facilitate biofilm
development. The porous organic carriers are manufactured from Kenaf plant stalks. The carriers
vary in size but are generally near 1 millimeter in diameter. These organic carriers have a very high
surface area relative to the particle size and facilitate faster settling compared to conventional
flocculant sludge. As such, the process intends to intensify activated sludge systems by adding a
biofilm component to increase biomass concentration while increasing settleability. The carriers
are removed from the RAS stream via a rotary drum screen and returned to the basins.
The MOB process has been implemented at a few municipal facilities over approximately the last
5 years. Notably, demonstration of the Nuvoda process was undertaken at the Edmonds WWTF in
Washington and the Forest Grove WWTF in Oregon in recent years. However, neither of these
facilities include oxidation ditches, so the findings are not directly applicable to the City.
By adding MOB directly to the existing oxidation ditch, the carriers should add a biofilm component
to the activated sludge, which may allow for some denitrification within the anoxic environment
internal to the biofilm. However, the relative effect that this will have on effluent TIN is difficult to
predict based on the limited data from similar operating facilities. Further, the system requires
screening to be added to the RAS system, which will require additional process building space that
will be costly and challenging to implement on the already constrained site. For these reasons, the
City’s WWTF is not recommended to be an early adopter of this technology.
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Attached Growth – Denitrification Filters for Tertiary Treatment
Various tertiary treatment systems exist for the purposes of removing nutrients from the
secondary effluent. The existing oxidation ditches are shown to full nitrify the effluent at design
conditions; therefore, a tertiary treatment system that provides denitrification may be considered
for this facility. Denitrification filters are the logical technology to review. These filters are a subset
of biofilm processes that can be used as a tertiary treatment process to aid in effluent TIN
reduction. In this process, nitrified effluent (in which most ammonia has been converted to nitrate)
is passed through a filter bed containing heterotrophic organisms that metabolized nitrate into
nitrogen gas in the anoxic conditions of the filter bed. This typically requires a carbon feed ahead of
the filter as most of the influent carbon has been reduced through the preceding secondary
process.
For this technology to be applied at the City, an effluent pump station would be required to lift
secondary effluent from downstream end of the clarifiers to the denitrification filters. This is not
recommended as the construction of an effluent pump station and filters on the existing site would
be extremely difficult to configure and implement, would be costly, and would further reduce the
available footprint at the WWTF. Further, implementation of a tertiary treatment system of any
sort will not inherently increase the WWTF capacity as it will not improve the activated sludge
system. As such, tertiary treatment systems, such as denitrification filters, are not considered
further for this facility.
Improvements to the Existing Oxidation Ditch System
Based on the analyses of the previous section, improving the existing oxidation ditch system is
likely to be the only feasible approach that does not constitute a complete replacement of the
existing system. The intent of this section is to review options for improving the existing system
that include limited mechanical and structural improvements, are relatively low cost, would extend
the useful life of the existing infrastructure , and would delay the need for major improvements.
The applicable options include:
1. The addition of anoxic tankage external to the oxidation ditches;
2. The creation of a dedicated anoxic zone internal to the oxidation ditches; and
3. Cyclic aeration of the oxidation ditches.
The anoxic zone tankage would need to equate to approximately 20 to 30 percent of the volume of
the existing ditches. There is no feasible method to add external anoxic tankage of this size to the
site based on the constraints identified in the WWTF Site Footprint. As such, the first option is not
considered applicable.
The two remaining options are analyzed in the following sections.
Creation of Dedicated Anoxic Zone Internal to Oxidation Ditches
The existing optimization strategy represents one method of creating an anoxic zone within the
oxidation ditches by reducing aeration to create a zone relatively devoid of oxygen. As previously
discussed, this configuration has significant limitations that preclude relying on this option through
the planning period.
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Another option consists of physically partitioning an anoxic zone and adding new equipment to the
system. The Modified Ludzack-Ettinger (MLE) process that fits this approach is one of the most
common activated sludge processes used for biological nitrogen removal. This process is shown in
Table 8-24, row (b) of Metcalf & Eddy (2013). The MLE configuration creates a dedicated anoxic
zone upstream of the aerobic zone. An internal recycle pump returns mixed liquor from the
downstream end of the aerobic zone to the anoxic zone at a high rate (typically 3 to 5 times the
influent flow rate) to return the nitrate for denitrification in the anoxic zone. Placement of the
anoxic zone upstream of the aerobic zone allows for influent carbon to be utilized for
denitrification.
To implement this configuration within the existing tankage at the WWTF, an anoxic zone would be
created with a physical partition within the ditch as shown in Figure 8-5.
Figure 8-5 – Conceptual Conversion of Existing Oxidation Ditches to MLE Configuration
Note: Single ditch shown.
As shown in the figure, this fundamental change to the ditch configuration essentially converts the
ditch from a closed-loop reactor to a staged, continuous flow reactor. The mixer/aerator, which is
necessary to provide a high degree of mixing and recirculation in a closed-loop reactor, would be
removed. The MLE configuration would utilize an internal recycle pump, new mixing equipment in
the anoxic zone, and diffused aeration with external blowers for the oxic zone. Additionally, it
would be prudent to place the partition adjacent to the mixed liquor outfall and relocate the
influent/RAS discharge location as shown in the figure to make the best usage of the tankage
volume.
These changes would consist primarily of mechanical equipment additions. There would be
significant new motor loads for the aeration blowers, mixing equipment, and internal recycle
pumps that likely would prompt major electrical system changes. Any approach that continues to
utilize the existing aerators and minimize equipment additions would be less costly than conversion
to the MLE configuration shown.
Further, these improvements would not be expected to significantly expand the system’s capacity
beyond the projected 2043 loading values. The system will remain inherently limited by the SLR
capacity of the two clarifiers. The MLE system could allow for modest improvements in aeration
system oxygen transfer and mixed liquor settleability, but these would only be expected to
incrementally increase the capacity of the activated sludge system with the existing two clarifiers.
The cost and complexity of this configuration, coupled with the minimal capacity expansion that it
affords, preclude this option from further consideration.
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Cyclical Operation of the Oxidation Ditches
As previously discussed, the City’s current TIN reduction optimization strategy creates an anoxic
environment in the oxidation ditches by operating the aerators in low speed . This approach creates
an anoxic zone internal to the ditch without necessitating physical partitions and other
improvements discussed in the Creation of Dedicated Anoxic Zone Internal to Oxidation Ditches
section.
Another approach to creating an anoxic environment in the ditches without physical partitions is to
create anoxic cycles by cyclically turning off the aerator periodically each day. This approach has
been utilized in multiple similar facilities to reduce TIN below 10 mg/L or less and is described in
Table 8-24, row (p) of Metcalf & Eddy (2013). This approach is readily applicable for retrofitting
facilities with two oxidation ditches. At a minimum, it would be necessary to add the following
items to the existing ditches:
• Mechanical mixing equipment for each ditch to maintain the activated sludge in suspension
during the anoxic cycles when the mixer/aerators are offline. This equipment likely would
consist of one or two low speed, large blade, submersible mixers.
• Oxidation-reduction potential control equipment to determine when the nitrate is depleted
to suspend the anoxic cycle.
Figure 8-6 illustrates the cyclical operation of the two oxidation ditches.
Figure 8-6– Conceptual Conversion of Existing Oxidation Ditches to Cyclic Operation
Note: Single ditch shown in either oxic or anoxic cycle.
There are some significant benefits to this approach. First, it represents limited structural and
mechanical improvements consisting primarily of small equipment additions and control system
programming. Further, it allows for continued use of the mixer/aerators, which decreases the cost
of this option relative to conversion to an MLE process. Lastly, this option could be implemented
with a relatively short outage of the existing tankage and by taking each ditch offline in series.
Conversion to cyclic operation generally should regain most of the permitted capacity of the WWTF
while providing for TIN reduction to below 10 mg/L. It is recommended that the capacity of this
system be based on an average annual clarifier SLR of 25 lb/d/sf. Based on Table 8-4, this would
equate to 1.40 MGD with one clarifier online, which is approximately the same as the current rated
capacity of the WWTF (1.44 MGD average annual). An average annual flow of 1.4 MGD is projected
to occur in approximately 2040 per Table 8-1. As previously noted, the City must begin planning for
an expansion of WWTF capacity when the facility exceeds 85 percent of its rated capacity.
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Assuming a capacity of 1.4 MGD with cyclical ditch operation, 85 percent would equal an
approximate average annual flow of 1.20 MGD, which is projected to occur by 2033.
Implementing cyclic operation is recommended soon as it will assist the WWTF in maintaining TIN
below 10 mg/L as growth in flow and loading occurs. These improvements are of limited
mechanical and structural scope and represent a relatively low-cost approach to regaining WWTF
capacity and maintaining TIN reduction with the existing system. Further, the ultimate TIN
requirements of the PSNGP are not yet finalized; therefore, delaying major improvements by
extending the useful life of the existing infrastructure is in the best interest of the ratepayers. This
approach is predicated on major improvements to the activated sludge system likely occurring
between 2033 and 2040, as 85 percent of the WWTF capacity is expected to be exceeded by 2033.
Replacement of the Existing Oxidation Ditch System
The analyses of the previous sections resulted in recommending cyclical operation of the oxidation
ditches as a near-term improvement that is minimally invasive to the WWTF. As discussed, this
approach may provide reliable TIN reduction as the City grows, although major improvements
should be planned and implemented to ensure continued, reliable treatment. Major improvements
also are anticipated given the age of the infrastructure. The useful life and capacity of this
infrastructure could be extended to approximately 2040 by making improvements to implement
cyclical oxidation ditch operation in the next 5 years. The City is fortunate to be able to get
extended life out of the oxidation ditches and replacement will be timely in addressing its age and
growth concurrently.
None of the options previously analyzed were shown to meet the TIN objectives at the flow and
loading levels expected at the end of the planning period due to the SLR limitation of the two
secondary clarifiers. Based on the initial review of alternatives in the Screening of Nitrogen
Treatment Options section, conversion to a plug flow, staged system is the only other practical
alternative that should be considered for the longer term improvements and capacity expansion of
the WWTF.
Plug flow, staged systems have been configured to provide a much higher rate of treatment
relative to oxidation ditches. A prudently designed plug flow system can allow for treatment
capacity that is double that of an oxidation ditch system with a similar footprint. The activated
sludge in a plug flow system should have substantially improved settleability compared to that of
an oxidation ditch system, which allows for a much higher clarifier SLR to be achieved. This enables
significantly increased MLSS concentrations to be achieved, which allows for a higher rate of
biological treatment per reactor area.
In 2022, the City commissioned a study on sea level rise impacts on Port Townsend, including
wastewater infrastructure. The City of Port Townsend Sea Level Rise and Coastal Flooding Risk
Assessment (Cascadia Consulting Group, 2022) is contained in Appendix K. As noted in the study, in
the long term, there will be impacts that could affect wastewater infrastructure. Any future
planning for improvements intended to last beyond the next 20 years should factor this study and
latest available information on sea level rise into the siting and hydraulics of the proposed
improvements. Figure 8-7 illustrates an open water connection between the Strait and Chinese
Garden Lagoon. This plan for future improvements (lasting beyond 20 years) takes into account this
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probability of sea level rise as illustrated in Figure 8-10. Refer to the Outfall section in this chapter
for further discussion on sea level rise.
Figure 8-7 – Sea Level Rise Projects for 17% Probability of Exceedance including Storm Surge
Given the effects of sea level rise, site constraints, and the need to apply the best known and
available technology to replace aging infrastructure and to improve the capacity of the WWTF,
options for replacing the oxidation ditches with a plug flow system are reviewed in this section.
On-Site Implementation of Plug Flow Reactors – Replace Existing Oxidation Ditches
It is likely that the only location plug flow reactors could be constructed onsite are within the
existing footprint of the oxidation ditches. Various methods of constructing such basins were
considered. The two primary approaches consist of the following:
• Option 1 – Conversion of each ditch, in series, into a plug flow aeration basin wit h multiple
partitioned zones, floor-mounted diffused aeration, internal recycle, and other
improvements.
• Option 2 – Complete demolition of the existing oxidation ditches and reconstruction of plug
flow aeration basins in this location.
The result of these analyses is that neither option is recommended for similar reasons noted in the
analyses of converting the existing oxidation ditches to an MLE or similar proces s. Substantial
structural improvements would be necessary for each ditch to ensure reliability and longevity.
There also would be significant new equipment, access platforms, electrical, and control items to
Open water
connection to Chinese
Garden Lagoon WWTF
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install. These items necessitate months of construction, resulting in an extended outage period for
each ditch. This outage would reduce the reliability and redundancy of the existing activated sludge
system and expose the City to substantial risk of permit violation for an extended period.
Further, this approach would not facilitate the future construction of a third clarifier as it would be
unlikely to create additional unused space on the WWTF site.
This approach is not considered further.
Off-Site Implementation of Plug Flow Reactors
The previous analyses have not identified a practical approach to provide sufficient treatment
capacity with TIN reduction at the existing WWTF beyond approximately 2040. As flow and loading
growth continues, constructing major improvements on the existing site becomes even more
challenging as the existing tankage must be maintained in operation through construction to
provide reliable treatment. As previously noted, limited improvements for cyclical ditch operation
should allow for continued use of the existing WWTF infrastructure to approximately 2040, which
will allow the City to begin planning for a major expansion of the WWTF. It is recommended that
this expansion be planned to be offsite and near the existing WWTF.
Figure 8-8 shows the existing site aerial with parcel lines and ownership, as well as the surrounding
areas.
Figure 8-8 – WWTF and Surrounding Parcels
Two parcels immediately west of Kuhn Street with the same owner could provide sufficient space
for an expansion of the WWTF. The utilization of these parcels most likely would include
construction of activated sludge system tankage, specifically plug flow aeration basins, at this
location.
In addition to procuring these parcels, vacating the 52nd Street ROW separating both parcels for the
purposes of providing a single contiguous parcel would help provide ample space for new oxidation
ditches and future facilities that may be needed well beyond the planning period.
Figure 8-9 shows these major considerations.
Port
Townsend
WWTF
Vacant parcels
(two)
Vacant ROW
Kuhn St.
53
rd
St
.
N
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Figure 8-9 – Adjacent Parcel Acquisition Considerations
Activated Sludge System Recommendations
The previous analyses resulted in the following major findings:
• The facility is projected to exceed 85 percent of the permitted BOD loading by 2033.
• The facility flow and loading is projected to reach its rated capacity at approximately 2043.
• The current optimization strategy effectively reduces TIN below 10 mg/L but results in a
significant reduction in the realistic capacity of the activated sludge system .
• Implementation of cyclical oxidation ditch operation, as an alternative to the current
optimization strategy, would be a relatively low cost approach to maintaining TIN reduction
until the expansion can occur.
• Providing TIN reduction at the flow and loading projected late in the planning period would
necessitate a major expansion of the WWTF that will be most effectively completed through
the acquisition of off-site adjacent parcels.
The recommended basic approach and phasing of the WWTF improvements follows.
Years 0 to 5 (2024 to 2028)
In the next 5 years, the City will need to coordinate with Ecology and the requirements of the Puget
Sound Nutrient General Permit, which may require the need to implement cyclical oxidation ditch
operation to ensure continued TIN reduction and maintain the existing activated sludge system
capacity. The City also should begin the early work preparing for the future major expansion of the
WWTF. This work generally should include the following:
• Complete a preliminary design for the cyclical oxidation ditch improvements (Capital
Improvement Project (CIP) F8 in Chapter 10). Determine if an Engineering Report meeting
the requirements of Washington Administrative Code (WAC) 240-173-060 will be required
by Ecology.
• Complete improvements to implement cyclical oxidation ditch operation (CIP F8 in
Chapter 10).
Vacate 52nd
St. ROW?
Potential future
extents of WWTF
property
N
Chinese
Gardens
City-owned
future operator
residence
Ku
h
n
S
t
.
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• Complete a Nitrogen Optimization Plan per the PSNGP and submit to Ecology by March 31,
2026.
• Complete other WWTF rehabilitation work to extend the life of the existing infrastructure in
the most economical manner feasible to avoid significant capital costs for items that will be
removed or reconfigured with the major expansion of the WWTF (Chapter 10).
• Acquire parcels of land to support the major expansion of the WWTF (CIP F11 in
Chapter 10).
Years 6 to 10 (2028 to 2033)
• Complete an Engineering Report per WAC 173-240-060 for the major expansion of the
WWTF. Submit the report for review and approval by Ecology (CIP F12 in Chapter 10).
• Commence permitting, preliminary design, and funding acquisition related to the major
expansion of the WWTF (CIP F12 in Chapter 10).
Years 11 to 20 (2034 to 2043)
During this period, the design and construction of the major expansion of the WWTF (CIP F12 in
Chapter 10) should be completed. A basic description of the proposed major improvements is
discussed in this section.
Pending the land acquisition and configuration of the new parcels, at a minimum, a new activated
sludge system would be constructed on the new parcels. The existing secondary clarifiers likely
could remain at the current location. With the implementation of biological treatment on the new
parcels, the existing oxidation ditches could be removed. This would allow for future secondary
clarifiers to be constructed within the footprint of the demolished oxidation ditches.
To provide TIN reduction, a conservative approach to planning the new activated sludge system
consists of two plug flow, staged aeration basins on the new parcels. The exact size, configuration,
and equipment options would be analyzed thoroughly and determined in a future Engineer ing
Report.
All influent flow by gravity to the existing WWTF is collected at the Influent Pump Station (IPS) and
pumped to the existing Headworks, with subsequent gravity flow to the oxidation ditches. The
proposed future configuration of the WWTF, with biological treatment on the higher ground of the
new parcels, will prompt significant changes to the hydraulic profile of the WWTF. Influent will
need to be lifted to the new aeration basins. In order to avoid an additional pump station between
the existing Headworks and the new basins, it would be most practical to construct a new
Headworks on the new parcels and refurbish or replace the existing IPS at or near its existing
location. This is further discussed in the following Preliminary Treatment section.
Figure 8-10 schematically displays a conceptual reconfiguration of the WWTF utilizing the currently
undeveloped parcels west of Kuhn Street.
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Figure 8-10 – Basic Configuration of Expanded WWTF
PRELIMINARY TREATMENT
Chapter 7 identified improvements to rectify conditions-based needs for the IPS and Headworks.
The most significant of these improvements include:
1. Wet well rehabilitation, piping and pump replacement, and electrical raceway replacement
at the IPS; and
2. In-kind replacement of the existing screen and grit equipment, and concrete channel
rehabilitation at the Headworks.
Summary of Analysis
Table 8-5 shows the design criteria for the existing IPS and Headworks from the original
construction drawings.
Remove existing
Headworks
building
New Headworks
building
Space for
additional
clarifiers
New aeration
basins
Kuhn St.
53
rd
St
.
N
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Table 8-5
Preliminary Treatment Design Criteria from 1990 Project
As shown, two pumps in service should provide a nominal flow of 4,500 gallons per minute (gpm)
(6.48 MGD). This is in excess of the projected 2043 peak hour flow of 6.06 MGD with one pump out
of service. The IPS should provide sufficient capacity and redundancy through the planning period.
In general, the Headworks equipment and channels were designed for a peak flow of
approximately 7 MGD, which is above the projected 2043 peak hour flow of 6.06 MGD. The
Headworks includes a single mechanical bar screen and a back-up channel with a manually raked
bar screen. However, the mechanical screen should provide sufficient capacity and the back-up
screen provides sufficient redundancy. As previously noted, a budgetary allocation is established
for the in-kind replacement of the screen if needed during the planning period.
Similarly, the grit removal system is expected to provide sufficient capacity through the planning
period, and any improvements needed will be for the in-kind replacement of aging equipment as
previously noted.
Recommendations
Based on this review, the existing IPS and Headworks should not require replacements during the
planning period to increase capacity or redundancy. As noted in Chapter 7, age and condition may
require replacement or repair in the next 5 to 10 years. However, as discussed in the Activated
Sludge System section, future replacement of the activated sludge system likely would provide the
opportune time to replace the existing preliminary treatment system. The overall approach to the
activated sludge system improvements involves constructing new aeration basins offsite, on the
currently vacant parcels west of Kuhn Street. As noted, this likely would necessitate constructing a
new Headworks facility on the new parcels, adjacent to the new aeration basins. With this
configuration, it is most likely that the IPS would be significantly changed or replaced and
potentially relocated. The IPS would lift all influent and return flows up to the new Headworks
Type Submersible, VS
Number 3.00
Capacity, Each (gpm)2,250
Horsepower, Each (hp)35
Parshall Flume 1
Throat Width (in)12
Bar Screen 1
Width (ft)1.50
Screenings Press 1
Grit Removal 1
Diameter (ft)10.00
Peak Capacity (MGD)7
Grit Classifier 1
Influent Pumps
Headworks
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location. The configuration of this infrastructure would be analyzed thoroughly in the future
Engineering Report as discussed in the Activated Sludge System section. Given that the preliminary
treatment system is expected to be replaced in conjunction with the activated sludge system
improvements planned for the second half of the planning period, it is prudent to extend the life of
this infrastructure through limited rehabilitation while avoiding significant sunk costs in improving
this system.
Further, the new Headworks will allow for improvements over the existing configuration. For
instance, the new Headworks should include mechanical fine screening, which will provide
2-dimensional screening with much improved screenings capture compared to the existing
1-dimensional bar screen. The fine screens would provide a minimum of ⅜-inch screening, and
¼-inch screening could be considered. Additionally, two mechanical screens could be included in
the new Headworks for redundancy and to reduce operational labor in the event of an outage of a
single mechanical screen. Similarly, a new grit removal system would present opportunities for
improvements relative to the existing grit system. Such improvements are not feasible to make to
the existing Headworks; therefore, it is prudent to extend the life of the existing infrastructure as
feasible while planning for a future new, off -site Headworks.
EFFLUENT DISINFECTION
Chapter 7 identified relatively minor repair and replacement needs for the existing chlorination
system. Replacement of the non-potable water pumps also was recommended and represents the
only capital improvement project identified based on the conditions assessment of the disinfection
system.
Summary of Analysis
The design criteria for the existing chlorine contact chambers is compared to the 2043 average and
peak hour flow values in Table 8-6.
Table 8-6
Disinfection System Design Criteria from 1990 Project
Design Criteria Quantity
Chlorine Contact Chamber 2
Volume, Each
cubic feet 6,480
gallons 48,500
2043 Average Annual Flow (MGD)1.46
2043 Peak Hour Flow (MGD)6.06
Contact Time (Both Tanks Online) (min)
at Average Annual Flow 96
at Peak Hour Flow 23
Maximum Chlorine Dose at Peak Flow (mg/L)6
Hypochlorite Feed Pumps 2
Hypochlorite Storage Tank (gal)5,200
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The typical design range for disinfection contact time based on average design flow is 30 to
120 minutes per Metcalf & Eddy (2013). With two contact tanks online at the 2043 average annual
flow of 1.46 MGD, there is 96 minutes of contact time, which is well within the accepted range.
With one tank offline, the contact time would be approximately 48 minutes, which is still within the
recommended range.
Typical design ranges for disinfection contact time based on peak design flow is 15 to 90 minutes
per Metcalf & Eddy (2013). The contact time of 23 minutes with two tanks online at the projected
2043 peak hour flow is within the recommended range. With one tank out of service, the contact
time would be reduced to approximately 12 minutes. While this is below the recommended range
and could cause an increase in coliform discharge, it is likely that weekly and month ly average
coliform values would remain below permit limits as the average contact times are sufficient.
Based on this analysis, expanding capacity, or improving redundancy of the chlorination system,
should not be required during the planning period.
Recommendations
No major improvements appear to be needed for the effluent disinfection system during the
planning period. Minor repairs and rehabilitation should be completed as ne cessary to maintain
reliable operation of the system. However, future sea level rise and other considerations may in the
long term require improvements to, or replacement of, the existing disinfection system.
OUTFALL
The City has received funding and is actively working with Ecology and Jacobs Engineering Group on
an evaluation and modifications to the existing outfall. The project is currently under further
alternatives evaluation. Initial evaluations of the outfall dating back to the 2000 Wastewater
Facilities Plan suggest that sliplining and pumping would be the least cost option. Since that time,
significant work has been completed, including the approval of a Facilities Plan Amendment in 2019
by Ecology. This amendment recommends digging in a parallel pipe to the existing pipe and
replacing the diffusers. This option has been recommended as the least cost option. Prior to
entering the permitting phase of the project, resource agencies and the public spoke out against
the project due to potential impacts to eel grass and kelp beds. Figure 8-11 illustrates the
approximate outfall configuration. Note, the difference between the Chinese Garden Lagoon and
the WWTF outfall. The Chinese Garden Lagoon outfall often is exposed on the beach and is
confused by the public as being the WWTF outfall.
The City’s WWTF outfall is always submerged; however, storms periodically expose and damage
the existing concrete pipe on the beach. Staff immediately repairs the concrete when damaged.
One need for the outfall project, no matter the solution , is to replace the beach section of pipe and
protect it against heavy North Beach surf.
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Figure 8-11 – Approximate Outfall Configuration
Staff is re-evaluating possible solutions, including sliplining the pipe. Staff also is considering the
impact of sea level rise on the Chinese Garden Lagoon. Currently, the outfall does not use the
Chinese Garden Lagoon; however, at a Marine Resources Committee meeting, a suggestion was
made to look for environmental improvements of combining the sewer outfall with the Chinese
Garden Lagoon.
Given this work is already underway, further evaluation in this GSP is not included and will be
handled in separate documents that will be submitted to Ecology for review and approval.
TERTIARY TREATMENT – WATER REUSE/RECLAMATION
The City currently discharges all of its effluent to the existing outfall. The City frequently hears from
the community about its desire to implement water reuse practices in the name of water
conservation and environmental stewardship. A detailed description of water reuse as it relates to
regulations and standards is included in Chapter 4 of the adopted 2019 Water System Plan (WSP)
(available on the City website). Given water reuse begins at the WWTF, the following information is
provided concerning the application of water reuse opportunities in the City, as well as financial
limitations.
How would reclaimed water from the WWTF be used in Port Townsend? Chapter 4 of the WSP,
specifically Table 4-7, lists all of the allowable uses and the associated class of reclaimed water
allowable for such use. In general, higher levels of treatment are required for reclaimed water
WWTF
Outfall Chinese Garden
Lagoon Outfall
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where there is a potential for human exposure, such as irrigation water. What is the greatest
environmental and societal benefit? How is water reuse helpful in the light of climate change and
sea level rise? These are all very good questions. The WSP outlines that the cost would be
prohibitive, thus no specific actions or investments are included in the WSP. This GSP outlines the
most common comments heard by the City and likely the most probabl e applications of water
reuse, recognizing that there is benefit to seeking opportunities. Practically, this GSP does not
include specific investments in the CIP given the rate impacts. However, staff recommends keeping
water reuse on the horizon and looking for grant opportunities to negate the capital cost of
operating a water reuse system. The following brief discussion of potential water reuse applications
provides very high level considerations.
• Water reuse for industrial process water is one option available. This option requires the
least amount of treatment because industrial water is non-contact use. Given that the City
has a huge industrial water user, the Port Townsend Paper Mill, this thought was brought
up in the recent Water Supply Agreement discussions. The City could reliably provide
approximately 900,000 gallons of the mill’s average daily use of 11 million gallons. A
reclaimed water pipeline would have to be constructed across the City from the WWTF to
the Paper Mill. This water supply pipeline would cost in the tens of millions to construct.
Depending on whether or not workers were exposed to the water determines the level of
treatment required. Likely, Class A treatment would be required. If tertiary or enhanced
treatment is required, funding for an order of magnitude cost estimate of $20 million
would be needed.
• Irrigation is the most common beneficial use of reclaimed wastewater. Due to human
exposure in parks and to food in gardens, Class A reclamation standards must be met. To
make reclaimed water available throughout the City, a second water system would need to
be created. These systems are constructed of purple pipe to reduce the chance of
accidental cross connection. Cities with reclaimed water available for irrigation also require
extensive investment at each property for cross-connection prevention as required by the
Washington State Department of Health. A more likely beneficial use of reclaimed irrigation
water is to focus on the large expanses of irrigated areas such as the Fort, golf course,
parks, and school play fields. This would help reduce peak water use by the City during the
summer months when irrigation demands increase water consumption from 1 MGD to
nearly 2 MGD. Note, water reclamation is limited to the irrigation season between May and
October for this application. Dedicated water pipelines, reservoirs, and pumps stations are
required to accomplish any type of irrigation use. The cost of this infrastructure is in
addition to the cost of enhanced or tertiary treatment. Given tertiary or enhanced
treatment is required, funding for an order of magnitude cost estimate of $20 to
$50 million would be required to build an irrigation system. Irrigation of the Fort, Jefferson
County fairgrounds, and nearby schools would require the least amount of infrastructure
development.
• Water reclamation for environmental benefit might be the most practical implementation
strategy. For example, the City is currently exploring options for enhancing the water
quality of the Chinese Garden Lagoon given its propensity for algae blooms. With sea level
rise, the lagoon will ultimately connect with the Strait of Juan de Fuca and provide an
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inland estuary that will result in great habitat enhancements. The question for this
application would be whether accelerating this connection would make sense or not with
wastewater discharge to the lagoon.
• Water reclamation for groundwater augmentation could be another practical use.
Groundwater injection occurs through either direct injection or percolation. The aquifer
under the City is not a drinking water supply and is approximately at sea level. A number of
irrigation wells exist within the City, including one owned by the City. Pumping of this
aquifer invites salt water intrusion on all three sides of the City. Infiltration of reclaimed
water can offset the impact of pumping. The exact configuration of the aquifer is not
readily known; therefore, a great amount of research would be required to validate this
approach for reclaimed water reuse. Depending on the level of treatment, investment
levels likely approach $10 million for this option.
All of the applications discussed require extensive permitting to ensure unintended consequences
are not a result. Given the extensive needs of investment in the foundational systems of the WWTF
and collection system, the rate payers may not be willing to pay for a reclaimed water system at
this time. Adding reclaimed water to the capital plan would require nearly doubling the investment
levels, which would more than triple current sewer rates. Therefore, this GSP recommends
expending resources on water reuse only if an environmental improvement grant makes it
financially feasible.
The improvements noted in the previous sections and in the Chapter 10 CIP will still need to be
implemented, even if the City decides to pursue tertiary treatment for water reclamation. Given
the space limitations and capital cost concerns, pursuing this further at this time is not feasible.
SOLIDS HANDLING
The conditions assessment in Chapter 7 identified primarily minor improvements to maintain
reliable operation of the solids handling system during the planning period. This chapter reviews
the potential improvements needed to ensure sufficient system capacity and redundancy is
available with this system. The analyses are divided between the on- and off-site solids handling
system components.
On-Site WWTF Solids Handling System
The existing on-site solids handling system includes two aerobic holding tanks followed by sludge
dewatering via a single belt press. The aerobic holding tanks where retrofitted during the
1990 project to provide waste activated sludge (WAS) storage. These concrete tanks originally were
constructed in approximately 1970. The dewatering system was installed in the 1990 project.
Dewatered sludge is composted as discussed in the Off-Site Compost Facility section.
Summary of Analysis
The on-site solids handling system is not intended to provide substantial stabilization of the WAS as
the solids are stabilized via off-site composting. As currently configured, the on-site system is
generally intended to equalize and store WAS to enable periodic operation of the dewatering belt
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press during normal staff hours. As such, the aerobic holding tanks are not required to provide
significant volatile solids destruction, and the dewatered sludge is not intended to meet Class B
requirements. The design criteria from the 1990 project for the existing aerobic holding tanks is
shown in Table 8-7.
Table 8-7
Aerobic Holding Tank Design Criteria from 1990 Project
At the 2043 maximum month loading condition, the WWTF is expected to produce WAS at
approximately 4,000 pounds per day (ppd) total solids. At an average concentration of 8,000 mg/L,
this equates to 60,000 gallons per day (gpd). As shown in Table 8-7, the two aerobic holding tanks
provide a total volume of approximately 360,000 gallons. With one tank offline, the system should
provide approximately 3 days of storage volume without thickening. The operators currently
decant the tanks to increase the solids concentration and reduce the volume fed to the belt press.
With or without decanting, 3 days should be sufficient equalization for the dewatering system
should one tank be offline. The aeration system also appears sufficiently sized to maintain an
aerobic environment in the tanks without allowing significant volatile solids destruction. By utilizing
the composting system to provide sludge stabilization, the aerobic holding tank system is expected
to provide sufficient capacity and redundancy in WAS storage through the planning period.
The design criteria from the 1990 project for the dewatering system is shown in Table 8-8.
Table 8-8
Dewatering System Design Criteria from 1990 Project
The belt press is currently operated up to 3 days per week for approximately 8-hour shifts. Based
on staff input, it is preferred that the belt press be operated no more than 4 days per week for
8 hours per day. Given this, the belt press is operating at about 75 percent or less of the allowable
operating time per week. Based on the projected increase in flow and loading in Table 8-1, sludge
production would be expected to increase approximately 20 percent by 2033 and 40 percent by
2043 compared to existing levels. As such, it is likely that the belt provides sufficient capacity to
approximately 2033 by operating up to 4 days per week. Beyond 2033, the belt press may need to
be operated up to 5 days per week to provide sufficient capacity or be replaced with a larger unit.
Aerobic Digesters Quantity
Number of Digesters 2
Total Volume (ft 3)6,480
Total Volume (gal)360,000
Digester Blowers 3
Capacity Each (cfm)720
Horspower, Each (hp)75
Dewatering System Quantity
Size (meters)1.5
Feed Rate (gpm/meter)50
Polymer Usage (lb/dry ton)30
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It should be noted that the City has a single belt press, so there is no inherent dewatering system
redundancy. If needed, the City could rent a mobile dewatering unit to process sludge.
Appropriately sized units for the City’s WWTF should be readily available for rental in an
emergency.
Recommendations
As noted in Chapter 7, the existing on-site solids handling system is generally in good condition. As
discussed in this section, the system provides sufficient capacity and redundancy for the City’s
needs. However, the aerobic holding system tankage is expected to be over 70 years of age at the
end of the planning period, while the belt press and ancillary equipment will generally be over
50 years of age by 2043. It is prudent to plan for replacement of the major mechanical equipme nt
for the solids handling equipment, such as the belt press, sludge pumps, blowers, etc., as well as
other refurbishments, such as the aerobic holding tankage, late in the planning period. It is difficult
to predict the scope of this work. Further, the WWTF is expected to be significantly reconfigured by
the end of the planning period as discussed in the Activated Sludge System section. Based on these
factors, it is recommended that the City establish a budgetary allocation for on-site solids handling
system improvements late in the planning period. As an initial allocation, $3 million is
recommended. The scope of the improvements and associated costs should be reviewed
thoroughly in the future, likely as part of the Engineering Report that will be required for the major
WWTF expansion project.
Off-Site Compost Facility
The City operates a Compost Facility at the Jefferson County (County) Transfer Station site. The City
transports dewatered sludge from the WWTF to the facility for composting. An aerial image of the
facility is included in the Chapter 7.
Summary of Analysis
The composting system utilizes the aerated static pile method. The facility includes two covered
areas, referred to as “barns.” The south barn occupies approximately 11,000 square feet (sf) and is
used for the aerated static piles. The north barn is 8,000 sf and is primarily used as a
finishing/storage barn. The City received carbon in the form of yard waste collected by the City’s
solid waste hauler and provided by self-haulers at the Jefferson County transfer station. The City
chips yard waste annually for use as a bulking agent in the composting process. The City owns
screening equipment, a front-end loader, and other heavy equipment necessary to operate the
composting system.
Based on the projected increase in loading shown in Table 8-1, sludge hauled to the compost
facility would be expected to increase approximately 20 percent by 2033 and 40 percent by 2043
compared to existing levels.
The City is also contracting to take waste activated sludge from the new Port Hadlock WWTF. Port
Hadlock will purchase and operate a gravity dewatering system and haul the dewatered sludge to
the Compost Facility. The City will mix with the Port Hadlock sludge with the City’s WWTF solids to
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compost on site. It is estimated that Port Hadlock will supply a 5 yard load approximately 8 times
per year.
The Compost Facility site has ample space for the existing operation and has sufficient available
space to expand in the future if desired. As growth occurs, the City likely will convert the north barn
first to house additional aerated static piles. At a minimum, this would consist of adding aeration
equipment to this barn. An additional barn likely would be the next major addition with growth.
Septage Receiving System
As discussed in Chapter 7, the City also receives septage to the Compost Facility from the County,
which necessitates a small SBR treatment plant at the facility. The SBR system discharges to an
engineered wetland treatment system west of the Compost Facility. As noted in Chapter 7, some
improvements to the SBR are required to replace and rehabilitate aging items. Septage solids are
mixed with City sludge and composted. For the purposes of this GSP, it is assumed that if septage
receiving were expanded, the overall impact on the solids portion of the composting operation
would not be significantly impacted. On the other hand, if septage receiving was expanded,
significant improvements to the liquid treatment potion of the compost facility would be required.
The current CIP in Chapter 10 includes operations and maintenance and repair/replacement
projects to keep the existing septage facility running for the next 20 years. This would keep the
system functioning at the same treatment capacity as current. However, the City was approached
by the County to evaluate options to take all of the County’s septage.
The City’s septage receiving facility currently handles approximately 40 percent of the County’s
total annual septage generation. The remainder is trucked to facilities outside of the County for
treatment. When including 20 years of growth, the facility would need to treat a maximum month
average daily flow of 6,500 gpd, and a peak day of 10,000 gallons. This is significantly higher than
the rated capacity of the existing facility.
Alternatives were analyzed, including upgrading the on-site facilities, trucking to the City’s main
WWTF, and building a pump station and pumping from the septage facility to the main W WTF. The
recommended alternative was to expand capacity at the site, as the other alternatives were much
more costly or unfeasible. The upgrade alternative would cost approximately $4M (2023 dollars).
This information was presented to County staff and County Commissioners for review.
The County is considering their options and the availability of funding. The next step for this
upgrade would be a dedicated Engineering Report to analyze and recommend the SBR
improvements and detail the associated costs.
As noted previously, this GSP only includes repair/replacement projects at this time. If expansion is
decided upon, and funding is found by the County, then a separate amendment would be
submitted.
ELECTRICAL AND CONTROLS
Chapter 7 identified necessary improvements for the electrical and control systems. Chapter 10
includes the CIP projects for these items to maintain the reliability and operability of these systems.
However, one of the main considerations for electrical improvements is the timing of the
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recommended motor control center (MCC) and generator replacements due to these items nearing
the end of their useful life. As discussed in this chapter, a major reconfiguration of the WWTF is
planned to support the necessary treatment objectives. As noted in the Activated Sludge System
Recommendations, the major improvements to the WWTF are likely to consist of abandonment of
the existing Headworks and oxidation ditches and replacement with a new Headworks and plug
flow aeration basins on adjacent property. Additionally, the IPS will be reconfigured or replaced to
pump to the new Headworks at a higher elevation than the existing Headworks. The project also
may include, or at least allow provisions for, an additional secondary clarifier on the existing site.
The improvements associated with the major reconfiguration of the WWTF will significantly impact
the electrical system at the WWTP by decommissioning major motor loads through removal of
existing processes, as well as adding new motor loads associated with the new systems. It would be
most economical for the City to maintain the existing MCCs and generator until they are completely
replaced through the major reconfiguration project. However, Chapter 7 conservatively
recommended replacement of this equipment in 5 to 10 years. This timing may be slightly in
advance of the major improvements that are expected to occur between 10 and 20 years. For
conservative planning purposes, it is recommended that the City budget for replacement of this
equipment in 5 to 10 years. However, pending the progress on the major improvements project, as
well as continued spare parts availability for the existing electrical equipment, it may be possible to
forego some of the recommended in-kind electrical equipment replacements prior to the major
reconfiguration project.
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REFERENCES
Metcalf & Eddy Inc., Tchobanoglous, G., Burton, F. L., Tsuchihashi, R., & Stensel, H.D. (2013).
Wastewater engineering: Treatment and resource recovery (5th ed.). McGraw-Hill
Professional.
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9 | OPERATIONS AND MAINTENANCE
INTRODUCTION
The City of Port Townsend’s (City) wastewater operations and maintenance (O&M) program
consists of the following elements:
1. Normal operation of the wastewater collection system, wastewater treatment facility
(WWTF), and Compost Facility.
2. Emergency operation of the wastewater collection system , WWTF, and Compost
Facility, when one or more of the components is not available for normal use due to
natural or human-made events.
3. A preventive maintenance program to ensure that the wastewater system is receiving
maintenance in accordance with generally accepted standards.
NORMAL OPERATIONS
City Personnel
The City’s wastewater division functions under the provisions of the City’s National Pollutant
Discharge Elimination System (NPDES) Permit and the direction of the Public Works Director.
Wastewater treatment facilities have special employment requirements for staff as outlined in
Chapter 70A.212 Revised Code of Washington (RCW).
In accordance with the RCW, it shall be unlawful for any person, firm, corporation, municipal
corporation, or other governmental subdivision or agency to operate or maintain a wastewater
treatment facility unless the individual persons performing the duties of an operator as defined
in NPDES Permit S.5.3.B, or in any lawful rule, order, or regulation, without being duly certified
under the provisions of the chapter.
The municipality is required to designate a person on site at its WWTF as the operator in
responsible command of the operation and maintenance of the system. This person is required
to be certified at a level equal to or higher than the classification rating of the facility, or
Group II for the City.
The WWTF also is required, while staffed on more than one daily shift, to have a shift
supervisor designated in charge of each shift at a level no lower than one level lower than the
classification rating of II for the City. Based on the RCW, all staff shall be subordinate to the
operator in responsible charge.
The current wastewater division organization structure is as shown in Figure 9-1. Staff must:
1. Institute adequate O&M programs for the entire sewage system;
2. Keep maintenance records on all major electrical, supervisory control and data
acquisition (SCADA), and mechanical components of the WWTF, as well as the
collections system and pumping stations. Such records must clearly specify the
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frequency and type of maintenance recommended by the manufacturer and must show
the frequency and type of maintenance performed ;
3. Ensure all operations and maintenance tasks done on the WWTF process equipment or
systems are operated or supervised by an operator certified by the State of Washington.
The Permittee may allow qualified mechanics, programmers, network engineers,
electricians, or other trained tradespersons appropriate for specific tasks to perform
work on equipment as long as a certified operator is on site to supervise, authorize , and
verify that the work performed does not adversely impact facility operations, effluent
quality, or process monitoring and alarm reliability; and
4. Make maintenance records available for inspection at all times.
Figure 9-1
Wastewater Division Organization Chart
Personnel Responsibilities
The key responsibilities of the wastewater O&M staff are summarized as follows.
Public Works Director – Under the direction of the City Manager, the Public Works Director
leads or facilitates planning, implements capital improvement projects, and directs the
Wastewater Seasonal and/or Apprentice
Vacant Currently
Operator
Josh Graves
Operator
Mike Bartkus
Public Works Director
Steve King
Operations Manager
Bliss Morris
Wastewater Treatment Facility Compost Facility
Operator
Jim Aman
Operator
Adam Freitas
Crew Chief
Vacant Currently
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long-term programs of the department, including Engineering and Construction, Streets
Maintenance and Collections, Stormwater, Transportation, Water Resources, Wastewater,
Compost Facility, Parks, Facilities, and contractual management of Trash Collection/Recycling.
Operations Manager – Under the direction of the Public Works Director, the Operations
Manager provides oversight and management of the City’s wastewater division. This position
coordinates planning objectives, capital improvement projects, and O&M plans to implement
City-defined objectives for the wastewater division. The Operations Manager coordinates
closely with other divisions and City departments to develop operational strategies, budgets,
and long-range planning efforts. The Operations Manager also serves as Operator in Charge
when there are vacant positions.
WWTF Operator Crew Chief – The Operator Crew Chief serves to assist the Operations
Manager in the leadership and management of the WWTF. This position provides backup and
support when the Operations Manager is unavailable or on leave.
WWTF Operators – The Operator is a fully skilled journey level position capable of operating
and maintaining all functional areas of the WWTF with minimal guidance or direction.
Compost Facility Operator – The Operator is a fully skilled journey level position capable of
operating and maintaining all functional areas of the Compost Facility with minimal guidance or
direction.
Wastewater Seasonal and/or Apprentice – The Apprentice will serve both the Compost Facility
and the WWTF to help with additional work and receive training to become a certified
Operator. This position will be especially important during construction of the WWTF upgrades,
when staff is stressed with additional work caused by construction disruptions.
Certification of Personnel
Table 9-1 shows the current certifications of the City’s WWTF and Compost Facility O&M staff.
Table 9-1
Personnel Certification
It is City policy to maintain a well-qualified, technically trained staff. The City annually allocates
funds for personnel training, certification, and membership in professional organizations. The
City believes that the time and money invested in training, certification , and professional
organizations are necessary to provide safety and meet permit compliance.
Last Name First Name
Certificate
Number Group
Morris Bliss 7234 II
Bartkus Mike 6354 II
Freitas Adam 8277 II
Aman Jim 8839 I
Graves Josh 8721 I
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Available Equipment
The wastewater division has several types of equipment available for daily routine O&M of the
wastewater system. If additional equipment is required for specific projects, the City will rent or
contract with a local contractor for the services needed. A stock of supplies in sufficient
quantities for normal system O&M and anticipated emergencies are stored at each facility. A
list of major equipment and chemicals used in the normal operation of the wastewater division
can be found in Table 9-2.
Table 9-2
Wastewater Division Equipment List
The following representatives typically provide supplies and chemicals to the City.
• Supplies: MASCO Petroleum, 727 Marine Drive, Port Angeles, WA 98363, (360) 640-4444
• Equipment: NAPA Auto Parts, 2321 W Sims Way, Port Townsend, WA 98368,
(360) 385-3131
• Equipment: McGuire Bearing Company, 915 S Center Street, Tacoma, WA 98409,
(253) 572-2700
Wastewater division employees are equipped with cell phones. The phones provide the
capability for personnel to communicate with other cities and Jefferson County as needed.
Routine Operations
Routine operations involve the analysis, formulation , and implementation of procedures to
ensure that the facilities are functioning efficiently and treating sewer to meet discharge
standards.
WWTF Compost Facility Collection System
MultiQuip Power 45 Tow Behind Generator Case Loader Vactor Truck with Rodder and Cutter
Katolight Tow Behind Generator John Deere Loader Push Camera
Chambers Boss LTG Light Tower John Deere Backhoe CCTV Camera Truck
12-inch Cargo Sport Box Trailer Rotomix Mixer (2) International Dump Truck (25%)
--Kubota/Brush Hog (33%)GMC Dump Truck (33%)
--International Dump Truck John Deere Loader (25%)
----Excavator (25%)
----John Deere Backhoe (33%)
----Skid Steer with Attachments (33%)
----Kenworth Dump Truck (25%)
----HMA Trailer (15%)
----Asphalt Roller (15%)
----Equipment Trailer (25%)
--Polymer RootX
--Methanol --
--Chlorine Gas --
Equipment
Chemical Inventory
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Continuity of Service
As the local sewer authority and publicly owned treatment works, the City shall maintain a
structure of authority and responsibility to ensure that wastewater service is continuous. For
example, changes in City Council or staff shall not have a pronounced effect on the City’s level
of treatment in terms of meeting the requirements of the NPDES Permit and water quality
standards.
Routine Wastewater Quality Sampling
The Washington State Department of Ecology (Ecology) has adopted federal regulations that
specify minimum monitoring requirements for the wastewater system. There are two types of
reporting at the treatment facility: process and compliance reporting. Process reporting
involves collecting data by analyzing samples collected in the facility and reporting the data to
the operations team. The data is used by the operations team to evaluate the facilit y’s
performance, monitor trends, and make appropriate daily adjustments. These minor daily
adjustments ensure the facility is continuously operated meeting the discharge limits identified
in the NPDES Permit. Compliance testing includes analytical and record data reported to
Ecology that demonstrates the City is compliant with the discharge limits. Reporting
requirements are contained in the NPDES Permit, a copy of which is included in Appendix C.
EMERGENCY OPERATIONS
Capabilities
The City is well equipped to accommodate short-term system failures and abnormalities. Its
capabilities are as follows.
Emergency Equipment
The City is equipped with the necessary tools to deal with common emergencies. If a more
serious emergency should develop, the City will hire a local contractor who has a stock of spare
parts necessary to make repairs to alleviate the emergency condition. The primary emergency
response tool for the collection system are two Vactor trucks and a portable back-up generator.
The WWTF and lift stations are monitored by staff through the Mission telemetry system.
Emergency Telephone
The wastewater division has an emergency phone number for public or City staff to directly
contact sewer department personnel after normal business hours. The number is
(360) 344-9779.
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Standby Personnel
The designated standby person can generally respond to a call within 30 minutes. A list of
emergency telephone numbers is provided to each on-call employee. New employees will be
added to the end of the list at the beginning of the next calendar year’s standby schedule.
Contacts
The City maintains a list of utility and agency contacts for routine and emergency use as shown
in Table 9-3.
Table 9-3
Utility and Agency Contacts
Material Readiness
Some critical repair parts, tools, and equipment are on-hand and kept in fully operational
condition. As repair parts are used, they are re-ordered. Inventories are kept current and
adequate for most common emergencies that reasonably can be anticipated. The City has ready
access to an inventory of repair parts, including parts required for repair of each type and size
of pipe within the service area. Additionally, the City has been provided with after-hours
emergency contact phone numbers for key material suppliers, which gives the City 24-hour
access to parts not kept in inventory. The City’s 24-hour contact at Ferguson is Daryl Clark at
(360) 340-8088.
Agency Phone
Jefferson County Public Utility
District (360) 385-5800 (24 Hours)
Astound (800) 427-8686
CenturyLink (833) 591-0933
JeffCom Non-Emergency Line (360) 344-9779
Other Emergencies 911
Ecology SW Regional Office (360) 407-6300 (24 Hours)
Department of Health
Shellfish
(360) 236-3330 (Daytime)
(360) 789-8962 (After Hours)
Jefferson County Health
Department (360) 385-9444
Utility Contacts
Agency Contacts
For collection system overflows, plant bypasses, upsets, or loss of
disinfection, contact the following immediately.
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PREVENTIVE MAINTENANCE
Maintenance schedules that meet or exceed manufacturer’s recommendations have been
established for all critical components in the City’s wastewater system.
Each year the Public Works Department cleans approximately one-quarter of the City’s sewer
lines. This process begins in March and is completed by the end of October.
The sewer lines are cleaned with a cleaning nozzle that is propelled from one maintenance hole
to the next using water under high pressure (1,500 to 2,000 pounds per square inch). The
nozzle is then pulled back to the starting maintenance hole. As the nozzle is pulled back, water
scours the inside of the sewer pipe. Any debris in the pipe is pulled back with the water. The
debris is removed from the maintenance hole with a vacuum unit. If roots are found, they are
cut with a root cutter. The City cleans and root cuts any problem areas on ce or twice per year.
City sewer lines requiring a higher level of maintenance are cleaned annually or semi-annually.
Per the recommendations in Chapter 6, the City will begin a video inspection program with the
goal of viewing the interior of all pipes and maintenance holes within the next 5 to 10 years.
This program will help identify mains most urgently in need of repairs or replacement and will
help prevent overflows.
The lift stations are checked three times weekly and include wireless monitoring and alarm
equipment for flows, backups, and power outages.
The following schedule is used as a minimum for preventive maintenance; the manufacturer’s
recommendations should be followed where conflict exists.
Wastewater Division
Wastewater Treatment Facility
Frequency Task or Activity
Daily Sample influent and effluent water quality per state and federal requirements.
As Needed Adjust the treatment process in the field as influent wastewater quality or
quantity changes to maintain high quality effluent.
As Needed Dewater the biosolids produced at the WWTF and haul the dewatered biosolids
to the Compost Facility.
As Needed Repair, maintain, and replace WWTF equipment.
As Needed Clean, paint, and perform small repairs at the WWTF buildings.
As Needed Clean and perform small repairs for the WWTF vehicles.
As Needed Water, mow, and trim the landscaping.
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Compost Facility
Frequency Task or Activity
Monthly Grease blowers, mixer, screen, and rotary screen thickener (RST). Check
mixer gear box and fill, if needed.
Monthly Run bio-filter fans and grease, if needed.
Monthly Exercise valves, spin blower shafts, and lift station heaters.
Monthly Fill shower drain and flush with hot water. Inspect fire extinguishers.
Monthly Change dissolved oxygen membrane and loader bucket pin.
Every 2 Months Spray down sequencing batch reactor (SBR).
Every 2 Months Sample compost for finished product quality.
Quarterly Sample water quality at the facility per state and federal requirements.
Quarterly Inspect the first aid kit.
Quarterly Clean the bar screen. Drain and clean the RST flock mixer tank.
Every 4 Months Clean catch basins and septage holding tanks.
Every 6 Months Grease motor control center room vent fan.
Every 6 Months Change oil for septage blower nos. 1 and 2 and the SBR blower.
Annually Sample water quality at the facility per state and federal requirements.
Annually Perform an annual safety inspection of the facility. Change batteries in the
smoke detectors.
Annually Grease screens and bio-filter fans. Change oil for the septage pump, air
filters, and tractor. Change fluids for the SBR mixer.
Annually Deep clean the RST and inspect lube latches.
Every 2 Years Change fuel at the filter diesel tank.
Every 2 Years Change oil for the pond pump, waste pump, filtrate pump, air compressor,
and pressure washer.
As Needed Water, mow, and trim the landscaping.
Sewage Lift Stations
Frequency Task or Activity
3 Times per
Week
Inspect and maintain the Gaines Street, Monroe Street, and Port Lift
Stations.
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Weekly Inspect and maintain the remaining smaller lift stations.
As Needed Perform routine maintenance on the pumps, valves, and controls.
As Needed Perform routine maintenance of lift station structures and surrounding site.
Collection System
Frequency Task or Activity
Semi-Annually Clean identified problem sewer lines of clogs and debris. Cut roots if found.
Annually Clean approximately 2.4 miles of sewers not identified as problem lines.
As Needed Inspect, clean, and evaluate maintenance holes and sewer pipeline condition
when hours are available for the program.
As Needed Perform unscheduled cleaning of periodic clogs and backups in the sewer
system.
As Needed Perform minor construction to maintain the existing system, including
maintenance hole cover replacements, maintenance hole replacements, and
spot pipe repairs.
STAFFING
The preventive maintenance procedures, as well as the normal and emergency operation s of
the utility, are described in the previous sections. The hours of labor and supervisory activity
required to effectively provide this ongoing maintenance and operations schedule forms the
basis for determining adequate staffing levels.
Current Staff
The City’s wastewater division staff currently includes approximately eight personnel assigned
to the operation and maintenance of the sewer system. The staff is made up of management
personnel and operators as shown in Figure 9-1.
Currently, the City’s wastewater collections, which is part of the Streets Maintenance and
Collections crew, consists of 2.23 full-time equivalents (FTEs). In addition, the WWTF has a total
of 3.5 FTEs, and the Compost Facility has a total of 2.5 FTEs.
Proposed Staffing
The City currently is preparing a rate study for the wastewater division. The following FTEs will
be planned for as part of this study.
The 2024 budget includes a position to increase the wastewater collections FTE count to 2.56.
In addition, the City is hoping to retain two seasonal positions, which would equate to 0.33 FTE
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annually, for seasonal assistance with the collections system. Therefore, a total of 2.6 FTEs is
recommended for the wastewater collections.
The City has budgeted in 2024 to add 1.0 FTE for the WWTF and Compost Facility. This new
position would be a shared maintenance worker with the ability to become an operator. This
position also is intended to help with the additional workload caused by projects being
performed at the WWTF. As a result, 0.5 FTE would be added to the WWTF, for a total of
5.0 FTEs. The other 0.5 FTE would assist with the Compost Facility, for a total of 3.0 FTEs.
Finally, the City has budgeted for a full-time electrician to be shared between the Facilities
(0.5), Water (0.2), and Wastewater (0.3) divisions.
After positions have been filled according to the 2024 budget, the following FTE counts apply
(including the Operation Manager’s pro-rated portion):
• Wastewater Collections – 2.6
• WWTF – 5.0
• Compost Facility – 3.0
• Total is 10.6 FTEs
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10 | CAPITAL IMPROVEMENT PLAN
INTRODUCTION
This chapter presents proposed improvements to the City of Port Townsend’s (City) sewer
system that are necessary to resolve existing system deficiencies and plan for the projected
sewer system growth. The sewer system improvements were identified from the results of the
collection system evaluation presented in Chapter 6, the Wastewater Treatment Facility
(WWTF) and Compost Facility evaluation presented in Chapter 7, and WWTF improvements
alternatives analyses presented in Chapter 8. The sewer system improvements were sized to
meet the system’s projected 2040 flow and loading conditions.
A Capital Improvement Plan number, herein referred to as a CIP number, has been assigned to
each improvement. The improvements are organized and presented in this chapter according
to the following primary categories. Note: The number symbol will be replaced with a
corresponding improvement number in the descriptions.
• 5-Year System Improvements
o Wastewater Treatment Facility Improvements (CIP F#)
o Compost Facility and Solids Handling Improvements (CIP C#)
o Lift Station and Miscellaneous Collection System Improvements (CIP WW#)
o Sewer Main Improvements (CIP SM#)
• 6- to 10-Year System Improvements
o Wastewater Treatment Facility Improvements (CIP F#)
o Sewer Main Improvements (CIP SM#)
• 11- to 20-Year System Improvements (long-term planning capital improvements)
o Wastewater Treatment Facility Improvements (CIP F#)
o Compost Facility and Solids Handling Improvements (CIP C#)
o Sewer Main Improvements (CIP SM#)
• Planning Improvements
o Miscellaneous and Planning Improvements (CIP M#)
The remainder of this chapter presents a brief description of each group of improvements, the
criteria for prioritization, the basis for the cost estimates, and the schedule for implementation.
For planning purposes, the improvement projects described herein are based on one
alternative route or conventional concept for providing the necessary improvement. Other
methods of achieving the same result, such as obtaining flow capacity increases by adding one
large gravity main versus using multiple gravity pipes, force main/gravity main combinations, or
multiple force mains, should be considered during design to ensure the best and lowest cost
alternative design is selected. Further evaluation should be performed when more information
is available regarding when and where future developments will occur.
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DESCRIPTION OF IMPROVEMENTS
This section provides a general description of each group of improvements and an overview of
the system deficiencies they will resolve. Some of the improvements are necessary to resolve
existing system deficiencies. These improvements are discussed in Chapters 6, 7, and 8.
Collection system improvements to accommodate new growth are not shown in detail in this
CIP. It is assumed that most of the new growth will occur at or near the Mill site. This CIP
includes a lift station to allow development of the Mill site and conveyance for the new lift
station’s discharge throughout the existing collection system.
It is intended that this General Sewer Plan (GSP) contain an inclusive list of recommended
system improvements; however, additional projects may need to be added or removed from
the list as growth occurs or conditions change. The City will evaluate the capacity of the
wastewater collection system, WWTF, and Compost Facility as growth occurs and as
development permits are received.
5-Year System Improvements
The following improvements were identified by City staff, from the results of the WWTF and
system analyses, and from previously prepared CIPs, as discussed in Chapters 6, 7, and 8. These
improvements are primarily necessary to serve the existing sewer service area. The
improvements include the major pipeline and facility construction that is required to properly
serve the existing sewer service area now and within the next 5 years. The improvement costs
shall be borne by the existing customers unless over-sizing of the improvements provides a
benefit to developers, in which case the City may pass those costs on depending on goals and
policies for development, especially as it relates to housing.
The improvements are based on existing peak hour flow rates; however, the proposed pipe
diameters for recommended replacement pipelines are based on peak hour flow projections.
The proposed system improvements are illustrated in Figure 10-1. RH2 Engineering, Inc.’s (RH2)
analysis shows the best apparent replacement alignment for the collection system
improvements based on information currently available. A variety of alternatives are possible
for the collection system CIP projects listed, and alternatives should and will be considered
during the design of each project.
Wastewater Treatment Facility Improvements (F#)
CIP F1 – Influent Pump Station and Odor Control Improvements
Deficiency: Portions of the Influent Pump Station (IPS) are heavily corroded, and the interior
liner is detaching from the concrete. The electrical conduits and equipment inside the pump
station also have corroded severely. In addition, a 2019 conditions assessment by Jacobs
Engineering Group (Jacobs) recommended odor control system improvements to increase
treatment capacity.
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Improvement: Repair the concrete liner system within the IPS and Headworks channels. Repair
the ductwork of the odor control system, upsize the fan, and add a new carbon tank. A full
conditions assessment of the mechanical components inside the IPS is recommended to
determine if the pipes and fittings need to be replaced. Replace the electrical and supervisory
control and data acquisition (SCADA) equipment and instrumentation inside the IPS. All flows
entering the IPS will need to be temporarily bypassed while improvements within the IPS are
being performed.
Cost: $2,120,000
CIP F5 – Non-Potable Water Pump Replacements (City to Install)
Deficiency: The existing non-potable water (NPW) pumps located at the end of the chlorine
contact basins are heavily corroded and in need of replacement.
Improvement: Replace the NPW pumps in-kind. Provide equipment and instrumentation
necessary to allow a fully functional and integrated system. This work is anticipated to be
completed by City staff.
Cost: $120,000
CIP F6 – SCADA Upgrades
Deficiency: The existing SCADA system at the WWTF is aging and in need of replacement as
spare parts become harder to acquire. The existing software is outdated and needs updating.
Improvement: Replace the programmable logic controller (PLC) and uninterruptible power
supply (UPS) equipment in all three control panels and replace the existing SCADA human
machine interface (HMI) computer hardware. Upgrade the network to an Ethernet Device Level
Ring network and convert the existing Allen-Bradley PLC-5 system to ControlLogix PLC
equipment.
Cost: $1,140,000
CIP F7 – Electrical Upgrades
Deficiency: Most of the existing electrical equipment and instrumentation is original to the
WWTF and is recommended to be upgraded or replaced as failures occur.
Improvement: Replace aging electrical equipment as failures occur and/or stock up on spare
parts. Replace all variable frequency drives (VFDs), aging field instrumentation, and
miscellaneous panel components.
Cost: $630,000
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CIP F8 – Near-Term Oxidation Ditch Improvements
Deficiency: Near-term improvements are recommended to upgrade the equipment at the
oxidation ditch. The system is losing treatment capacity due to the nitrogen removal operations
at the WWTF.
Improvement: Upgrade the oxidation ditches to replace one of the mixer aerators in-kind, and
install independent mechanical mixers and instrumentation and access platforms at both
ditches. Install the necessary equipment and instrumentation to automate flow isolation into
the ditches. These improvements will enable cyclical operation of the ditches by alternating
between oxic and anoxic cycles as discussed in Chapter 8. A preliminary design for the ditches is
recommended before implementing the improvements. While the improvements are being
performed within the ditches, rehabilitate the structures and remove sludge and grit as
necessary.
Note that the engineering will begin in the 5-year plan, but the City has currently budgeted
construction in the 6- to 10-year CIP for purposes of rate mitigation. However, if funding can be
procured, this project should be constructed sooner to minimize potential risk.
Cost: $2,940,000
CIP F9 – Outfall Upgrades
Deficiency: The existing outfall needs to be replaced due to the age of the infrastructure.
Improvement: Plan and design a replacement outfall project.
Cost: $4,000,000
CIP F11 – Land Acquisition for WWTF Expansion
Deficiency: The WWTF will require additional footprint to construct additional infrastructure
necessary for providing sufficient long-term treatment capacity.
Improvement: In anticipation of the future WWTF expansion, acquire additional parcels of land
as described in Chapter 8.
Cost: $2,000,000
Compost Facility and Solids Handling Improvements (C#)
CIP C1 – Solids Handling Influent Screening and Grit Removal
Deficiency: The bar screens currently are manually raked and washed down by haulers. This
process should be automated and grit should be removed in the process.
Improvement: Install a packaged septage screening and grit removal system with a new
influent meter to monitor flow.
Cost: $890,000
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CIP C2 – Solids Handling Tank Replacement and Mechanical Upgrades
Deficiency: One of the two existing septage holding tanks has accumulated a significant amount
of grit, making only one tank operable. The equipment associated with the septage treatment
system also needs to be replaced due to its age.
Improvement: Replace the existing solids handling tanks with a larger 50,000-gallon holding
tank with new blowers. Replace the pumps for the waste activated sludge (WAS), chlorination,
and wetland disposal processes, and replace the sequencing batch reactor (SBR) blower.
Cost: $700,000
CIP C3 – Compost Screen Replacement
Deficiency: The existing composting screen is nearing the end of its useful life and is due for
replacement.
Improvement: Install a new compost screen to replace the existing screen.
Cost: $460,000
CIP C4 – Compost Case Loader Replacement
Deficiency: The existing front-end loader in the Compost Facility is nearing the end of its useful
life and is due for replacement.
Improvement: Replace the existing front-end loader with a new loader.
Cost: $390,000
CIP C5 – Compost Blowers Replacements
Deficiency: The existing composting aeration blowers are nearing the end of their useful life
and are due for replacement.
Improvement: Replace the existing compost blowers with new compost blowers.
Cost: $80,000
CIP C7 – 6-Inch Hydrant Line
Deficiency: The Compost Facility needs additional water supply to meet process demands.
Improvement: Install approximately 1,100 linear feet (lf) of 6-inch water main from the facility’s
primary water main and connect to a hydrant located on the Compost Facility site.
Cost: $670,000
CIP C8 – Office with Dedicated Lunchroom
Deficiency: Expanding the Compost Facility and its associated processes will require more space
for City staff.
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Improvement: Add an office space with a dedicated lunchroom for City operators and staff use.
Cost: $300,000
Lift Station and Miscellaneous Collection System Improvements (WW#)
CIP WW1 – Existing Monroe Street Lift Station Improvements
Deficiency: The existing Monroe Street Lift Station does not have adequate pumping capacity
to meet existing hydraulic loads. The sewers on Lawrence Street, tributary to the Monroe Street
Lift Station, are still combined and the station is overwhelmed by stormwater inflow during
peak rainfall events. These extreme events cause all three pumps at the station to run. The
pump capacity deficiency could be mitigated by the separation of storm sewers from sanitary
sewers on Lawrence Street. For this reason, the upgrade of the lift station should be performed
after the Lawrence Street sewer separation project (CIP SM9) and after flows into the Monroe
Street Lift Station have been observed for at least 2 years.
The station must be relocated or elevated to prevent the access hatches from being inundated
as sea level continues to rise.
Improvement: Relocate the station to a new site that minimizes the risk of flooding over a
75-year design life. Rebuild the Monroe Street Lift Station with pumps, valves, and electrical
gear capable of handling the higher flow rates being received. Begin predesign for this project
after the Lawrence Street storm and sanitary sewer separation project has been completed and
influent flows have been analyzed. It is possible that influent flows to the Monroe Street Lift
Station could be significantly reduced with the Lawrence Street improvement project.
Cost: $5,000,000
CIP WW2 – Sewer Camera Van, Video Camera and Tractor, Recording Software and
Hardware, and Staff Training
Deficiency: The City’s existing video inspection equipment is outdated and no longer
functioning. New pipeline video equipment is needed to allow the City to inspect every pipe in
its system at least once every 10 years, and preferably every 5 years. Lack of functioning video
inspection equipment leaves the City unaware of the condition of its aging collection system.
The Water Street collapse may have been avoided if the City were able to see its deteriorating
condition. Knowledge of pipeline condition is an essential component of an asset management
system to schedule and budget repairs and replacements of aging mains and maintenance
holes.
Improvement: Procure new video camera, camera tractor, and software to record, store, and
annotate digital videos. Procure a van to house the equipment with power supply, cable reels,
and workstation with multiple monitor screens. This CIP item also includes training for the new
equipment.
Cost: $300,000
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CIP WW3 – General Lift Station Improvements
Deficiency: Replace components at various lift stations as needed due to aging parts and
equipment failures.
Improvement: Replace pumps, generators, valves, electrical power supply equipment, and
other essential lift station components as needed.
Cost: $1,000,000
CIP WW4 – Mill Lift Station
Deficiency: Currently, there is no sewer service at the Mill site. This lift station and force main
will allow for development of the Mill site to its potential.
Improvement: Procure property and construct a submersible lift station with an ultimate firm
capacity of 1,062 gallons per minute. The station is to include backup power generation and a
4,500-foot-long, 10-inch-diameter force main as shown in Figure 10-1. Costs also include gravity
piping in the area to supply the lift station.
Cost: $6,300,000
Sewer Main Improvements (SM#)
CIP SM1 – Sims Way Crossing and Wilson Street Realignment
Deficiency: The concrete gravity sewer main in W Sims Way and Wilson Street lacks the
hydraulic capacity to convey the projected 5-year flows from the proposed Mill Lift Station.
Furthermore, portions of this pipeline pass beneath an existing residence.
Improvement: Replace approximately 786 lf of existing 8-inch gravity pipe with new 18-inch
gravity sewer in a different alignment on an easement to be procured. This project must be
completed concurrently with the construction of the Mill Lift Station (CIP WW4).
Cost: $1,212,000
CIP SM8 – Sewer System Defect Investigation and Repair
Deficiency: There are a number of known structural deficiencies throughout the sewer system,
particularly in the older parts of the sewer collection system. The degree of structural
degradation at sites the City was able to video inspect indicate there may be additional
structural defects in other areas of the system.
Improvement: Systematically investigate and repair high priority, compromised sewer mains
with an emphasis on the areas of known structural degradation. Investigations will include
video inspections with some smoke testing of gravity sewer mains in areas where defects are
suspected by the City’s collections operations staff. Replacements will be made to the extent
allowed by the yearly collection system repair budget.
Cost: $3,300,000
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CIP SM9 – Lawrence Street Combined Sewer Separation
Deficiency: The Lawrence Street sewer combines sanitary sewer and stormwater in the same
pipe. Stormwater peak flows impose significant hydraulic loads on the sanitary sewer collection
system and the Monroe Street Lift Station and consumes treatment capacity at the WWTF.
Improvement: Reconstruct the storm and sanitary sewer collection pipelines in Lawrence
Street from Fillmore Street to Monroe Street to fully separate the storm drains. Perform smoke
testing and video inspection of the Lawrence Street sewer first to determine the level of
connectivity between the storm and sanitary sewers. The amount of asphalt disturbance will
require full street repaving and modification of street geometric design to provide Americans
with Disabilities Act compliant ramps at intersections. This project is split evenly with the City’s
stormwater division because of the magnitude of the cost and the equal benefit received by the
wastewater and stormwater divisions. The cost shown is the half share to be funded by the
City’s wastewater division.
Cost: $2,826,000
CIP SM10 – Suitcase Pipe Replacement on Washington Street
Deficiency: During a video inspection in 2023, it was observed that the vitrified clay pipe in
Washington Street between Taylor and Adams Streets was becoming crushed and in imminent
danger of collapse. The video inspector classified the failure as a “suitcase” because of cracks
observed at the 12, 3, 6 and 9 o’clock positions on the pipe. These cracks were acting like
hinges, allowing the pipe to slowly close like a suitcase. Replacement of this main is urgent to
prevent it from completely losing its ability to convey wastewater.
Improvement: Replace the existing pipeline with new 8-inch polyvinyl chloride (PVC) pipe by
open-cut methods.
Cost: $399,000
CIP SM12 – Water Street Sewer Replacement
Deficiency: The existing 14-inch-diameter, asbestos cement pipe in Water Street collapsed
during a king tide on December 27, 2022. After an emergency repair of the collapse, video
inspection of the 14-inch gravity sewer detected corrosion, broken pipe, and sediment
accumulation in the main, indicating a breach in the pipeline. The sediment prevented a full
pipeline inspection and hydraulic cleaning methods were abandoned because of the risk to the
fragile main. In early 2023, the City deemed the main to be in immediate need of replacement
and applied for funding. The City received funding from the State of Washington’s Public Works
Board in August 2023, and design has been underway since that time with the intent of
constructing the project in 2024.
Improvement: Replace approximately 1,600 lf of existing 14-inch gravity pipe by extending the
Monroe Street Lift Station force main by approximately 1,600 feet. This extension will be made
by horizontal directional drilling (HDD). Approximately 350 feet of the gravity main will be
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converted to force main by pipe bursting or sliplining the existing gravity main. Four service
laterals, currently connected to the gravity main being converted to a force main, will be
transferred to an 8-inch main sliplined into the failing 14-inch gravity sewer.
Cost: $2,100,000
6- to 10-Year System Improvements
The 6- to 10-year improvements were identified from the results of the WWTF and system
analyses discussed in Chapters 6 and 7 and the WWTF improvements alternatives analyses
presented in Chapter 8.
The 6- to 10-year system improvements are illustrated in Figure 10-1. Alternatives for the
collection system improvements are possible, and further evaluation should be performed
when more information is available regarding when and where future developments will occur.
Wastewater Treatment Facility Improvements (CIP F#)
CIP F2: Headworks Rehabilitation
Deficiency: The existing Headworks screen and grit mechanism are aging and in need of
replacement.
Improvement: Install a new replacement screen and remove the existing grit mechanism to
install a new mechanism and appurtenances. Increase the power feeder size and pr ovide
instrumentation for a fully integrated system.
Cost: $1,200,000
CIP F3 – Clarifier No. 1 Improvements
Deficiency: The original secondary clarifier mechanisms are reaching the end of their useful life
and are in need of replacement. Improvements are planned to be phased so that one clarifier
can remain online.
Improvement: Replace the existing Clarifier No. 1 mechanism with a stainless steel mechanism,
replace the drive unit, and recoat the launder. Remove the existing power feeder conductors
and re-land the conductors after the mechanism replacement is complete. Perform a conditions
assessment to determine if other improvements are needed.
Cost: $1,250,000
CIP F4 – Clarifier No. 2 Improvements
Deficiency: The original secondary clarifier mechanisms are reaching the end of their useful life
and are in need of replacement. Improvements are planned to be phased so that one clarifier
can remain online.
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Improvement: Replace the existing Clarifier No. 2 mechanism with a stainless steel mechanism,
replace the drive unit, and recoat the launder. Remove the existing power feeder conductors
and re-land the conductors after the mechanism replacement is complete. Perform a conditions
assessment to determine if other improvements are needed.
Cost: $1,250,000
Sewer Main Improvements (CIP SM#)
CIP SM2 – Howard Street and S Park Avenue
Deficiency: The gravity sewer main in Howard Street and S Park Avenue has hydraulic capacity
deficiencies, and a portion of these sewer mains need to be upsized.
Improvement: Replace approximately 1,079 lf of existing 8-inch gravity pipe with new 15-inch
gravity sewer pipe by open-cut methods as shown in Figure 10-1.
Cost: $1,578,000
CIP SM3 – Sims Way, 3rd Street, and Gise Street
Deficiency: The gravity sewer mains in Sims Way, 3rd Street, and Gise Street have hydraulic
capacity deficiencies, and a portion of these sewer mains need to be upsized.
Improvement: Replace approximately 273 lf of existing 8-inch gravity pipe with new 18-inch
gravity sewer pipe, and replace approximately 523 lf of existing 8-inch gravity pipe with new
15-inch gravity sewer pipe by open-cut methods as shown in Figure 10-1.
Cost: $1,186,000
CIP SM4 – Holcomb Street
Deficiency: The gravity sewer main in Holcomb Street has hydraulic capacity deficiencies and a
portion of the sewer main needs to be upsized.
Improvement: Replace approximately 531 lf of existing 12-inch gravity pipe with new 18-inch
gravity sewer pipe by open-cut methods as shown in Figure 10-1.
Cost: $819,000
11- to 20-Year System Improvements (Long-Term Planning Capital
Improvements)
The long-term improvements were identified from the results of the WWTF and system
analyses discussed in Chapters 6 and 7 and the WWTF improvements alternatives analyses
presented in Chapter 8. These improvements are necessary to serve projected population
growth in the City and expansion areas. The improvements include the major facility and
conveyance construction that will be required to serve those areas.
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The additional system improvements required for long-term improvements are illustrated in
Figure 10-1.
Wastewater Treatment Facility Improvements (CIP F#)
CIP F12 – Long-Term WWTF Expansion (Budgetary Estimate)
Deficiency: Long-term, major expansion of the WWTF is required to provide biological
treatment for the projected flow and loads and to provide nitrogen removal.
Improvement: Construct a new activated sludge system consisting of aeration basins and
secondary clarifiers. This involves constructing new aeration basins on the newly acquired
parcels and removing the existing oxidation ditches to construct future secondary clarifiers
within the existing footprint. Modify the hydraulics of the WWTF such that influent flow is lifted
to the new aeration basins. This may involve constructing a new Headworks and refurbishing or
replacing the existing IPS.
Cost: $30,000,000
Compost Facility and Solids Handling Improvements (C#)
CIP C6 – Compost Facility Infrastructure Upgrades
Deficiency: The Compost Facility needs infrastructure upgrades to bring the facility up to
current codes and to ensure safety for the operators.
Improvement: Perform infrastructure upgrades at the Compost Facility, including repairing and
sealing the asphalt around the facility, adding lights to the barns, and reinforcing the existing
concrete support poles of the barns.
Cost: $410,000
Sewer Main Improvements (SM#)
CIP SM5 – Howard Street, S Park Avenue, and McPherson Street
Deficiency: The gravity sewer mains in Howard Street, S Park Avenue, and McPherson Street
have hydraulic capacity deficiencies, and a portion of these sewer mains need to be upsized.
Improvement: Replace approximately 1,685 lf of existing 8-inch sewer with new 15-inch gravity
sewer pipe by open-cut methods as shown in Figure 10-1.
Cost: $2,463,000
CIP SM6 – West Sims Way and 3rd Street
Deficiency: The existing 8-inch concrete gravity sewer mains in West Sims Way and 3rd Street
have hydraulic capacity deficiencies, and a portion of these sewer mains need to be upsized.
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Improvement: Replace approximately 1,150 lf of existing 8-inch concrete sewer main with new
15-inch gravity sewer pipe by open-cut methods as shown in Figure 10-1.
Cost: $1,679,000
CIP SM7 – Future Interceptor Sizing
Deficiency: Existing 8-, 10-, 12-, and 18-inch sewer interceptor in the City’s collection system is
failing and has hydraulic capacity deficiencies. Portions of the sewer interceptor need to be
upsized.
Improvement: Replace approximately 3,785 lf of existing 10-, 12-, and 18-inch sewer
interceptor. Install approximately 220 lf of new 15-inch sewer interceptor, approximately
1,365 lf of new 18-inch sewer interceptor, approximately 1,165 lf of new 24-inch sewer
interceptor, and approximately 1,035 lf of new 30-inch sewer interceptor by open-cut methods
as shown in Figure 10-1.
Cost: $6,722,000
CIP SM11 – Long-Term Sewer System Investigation and Refurbishment
Deficiency: It is suspected that there are many structurally deficient sewer mains in the City’s
collection system. There are several known structural deficiencies, particularly in the older parts
of the collection system that have been video inspected. The degree of structural degradation
observed (such as Water and Washington Streets) indicates there are other structurally
deficient mains in the older parts of the sewer collection system. The condition of the collection
system is not well known because of a lack of adequate inspection equipment. The pipe
material and age of many of the mains is also unknown because of incomplete record drawings.
RH2 believes that many structurally deficient mains will be discovered once the City begins a
regular video inspection program and many of these mains will need to be replaced or repaired.
Improvement: Systematically investigate all un-inspected sewer mains with an emphasis on the
areas of known structural degradation that pose a threat of imminent pipe collapse. Replace or
line the existing mains and maintenance holes that are structurally deficient. The cost
presented represents the “least optimistic” scenario. That is, all pipes that are of concrete,
vitrified clay, asbestos cement, or unknown material are assumed to be deficient and will need
lining using cured-in-place pipe (CIPP) starting in 10 years. The estimated cost could be reduced
if vitrified clay pipes are still in good condition or if unknown pipes are made of PVC. If pipes are
in such dire condition that they cannot be lined (like the Water Street sewer in 2023), a more
expensive open-cut replacement method will be required. To be conservative, RH2 has
estimated that all pipes of substandard or unknown material will be lined with CIPP.
Cost: $56,000,000
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Planning Improvements
Miscellaneous and Planning Improvements (CIP M#)
CIP M1 – Arc Flash Analysis
Improvement: Perform an electrical short circuit, protective device coordination, and arc flash
analysis for the electrical distribution equipment at the City’s wastewater facilities. Prepare a
report summarizing the calculations and recommendations for protective device settings and
Personal Protective Equipment requirements.
CIP M2 – Public Works Shop (Sewer Collection Share)
Deficiency: The City Shops is home to the water, streets, stormwater, and wastewater
collections maintenance crews and equipment. The shops are in disrepair and a new
maintenance facility is needed. The first step is to do a schematic design and needs assessment.
Improvement: The cost shown is the share to be funded by the City’s Sewer Utility. The
estimated cost for the sewer utility portion of this assessment is $100,000.
CIP M3 – General Sewer Plan Update
Deficiency: The City’s GSP should be updated every 10 years in coordination with its Water
System Plan update.
Improvement: The City plans to update its GSP every 10 years. In addition, the City may review
the GSP at the 5-year mark and adjust the projections and improvements as necessary. This
may be completed between 2032 and 2033, and 2042 and 2043.
CIP M4 – Downtown Restrooms
Improvement: The cost shown is the share to be funded by the City’s Sewer Utility. The
estimated sewer fund cost is $250,000. Costs may vary depending on the location and size of
the facility. This estimate is planning-level only and anticipates use of other funding sources to
assist in the project development.
ESTIMATING COSTS OF IMPROVEMENTS
Project costs for the proposed improvements were estimated based on costs of similar recently
constructed sewer projects around the Puget Sound area and are presented in 2023 dollars.
The unit costs for each pipe size are based on estimates of all construction-related
improvements, such as materials and labor for installation, services, maintenance holes,
connections to the existing system, trench restoration, asphalt surface restoration, and other
work for a complete installation. Project cost estimates for sewer pipe projects were
determined from the unit costs (i.e., cost per foot-length) shown in Tables 10-1 and 10-2 and
the proposed diameter and approximate length of each improvement. The costs shown in
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Tables 10-1 and 10-2 include indirect costs estimated at 50 percent of the construction cost for
engineering preliminary design, final design, construction contract administration, project
administration, permitting, and legal and administrative services.
Table 10-1
Gravity Sewer Pipe Unit Costs for Open-Cut Construction
Table 10-2
Gravity Sewer Pipe Unit Costs for Cured-in-Place Pipe
The cost estimates shown in Table 10-3 include the estimated construction cost of the
improvement and indirect costs estimated at 50 percent of the construction cost for
engineering preliminary design, final design, construction contract administration, project
administration, permitting, and legal and administrative services. The construction cost
estimates include a sales tax of 8.6 percent.
Cost estimates prepared by RH2 for projects in the CIP are Class 5 estimates, based on
standards established by the American Association of Cost Engineers (AACE). Class 5 estimates
Sewer Main
Diameter
(in.)
Project Cost per
Linear Foot
(2023 $ per lf)
8 $1,314
12 $1,394
15 $1,461
18 $1,542
21 $1,668
24 $1,802
30 $2,119
36 $2,501
Sewer Main
Diameter
(in.)
Project Cost per
Linear Foot
(2023 $ per lf)
6 $350
8 $322
10 $331
12 $341
14 $399
15 $399
16 $475
18 $475
22 $686
24 $974
30 $1,357
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are described as generally being prepared with limited information and subsequently have wide
accuracy ranges. The typical accuracy range for this cost estimate class is from -20 percent
to -50 percent on the low side and from +30 percent to +100 percent on the high side.
The final cost of the projects will depend on actual labor and material costs, actual site
conditions, productivity, competitive market conditions, final project scope, final project
schedule, and other variable factors. As a result, the final project cost s likely will vary from
those presented. Because of these factors, funding needs must be reviewed carefully prior to
making specific financial decisions or establishing final budgets.
PRIORITIZING IMPROVEMENTS
The existing system improvements were prioritized by the City based on the perceived need for
the improvement to be completed prior to projects with fewer deficiencies or less risk of
damage due to failure of the system. Priority and schedule for any future developer-funded
projects is dependent on the timing and design of specific developments areas.
Future projects that are not identified as part of the City’s CIP may become necessary. Such
projects may be required to remedy an emergency situation or address unforeseen problems.
Due to budgetary constraints, the completion of such projects may require modifications to the
recommended CIP. The City retains the flexibility to reschedule, expand, or reduce the projects
included in the CIP and to add new projects to the CIP, as best determined by rate payers and
the City Council, when new information becomes available for review and analysis.
SCHEDULE OF IMPROVEMENTS
The results of prioritizing the improvements were used to assist in establishing an
implementation schedule that can be used by the City for preparing its CIP. The implementation
schedule for the proposed improvements is shown in Table 10-3. It should be noted that the
implementation schedule shown is, to some extent, flexible. The implementation schedule
should be modified based on City preferences, budget, or as development fluctuates. The City
should review Table 10-3 at least annually and reprioritize as necessary to match budget,
growth, flows, and other City conditions/priorities. This provides the City with the flexibility to
coordinate these projects with road or other projects within the same area.
Future Project Cost Adjustments
All cost estimates shown in the tables are presented in 2023 dollars. Therefore, it is
recommended that future costs be adjusted to account for the effects of inflation and changing
construction market conditions at the actual time of project implementation. Future costs can
be estimated using the Engineering News Record Construction Cost Index for the Seattle area or
by applying an estimated rate of inflation that reflects the current and anticipated future
market conditions.
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The CIP presented in Table 10-3 is based on the information currently available. As the City
implements the recommendations, the cost and timing of projects may be revised.
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Table 10-3
Proposed CIP Implementation Schedule
Estimated
CIP Length Cost
No.(LF)(2023 $)2024 2025 2026 2027 2028 6-10 years 11-20 years
SM1 786 $1,212,000 $100K $606K $506K
SM2 1,079 $1,578,000 $1,578K
SM3 796 $1,186,000 $1,186K
SM4 531 $819,000 $819K
SM5 1,685 $2,463,000 $2,463K
SM6 West Sims Way and 3rd Street 1,149 $1,679,000 $1,679K
SM7 Future Interceptor Upsizing 3,785 $6,722,000 $6,722K
SM8 --$3,300,000 $150K $350K $350K $350K $350K $1,750K
SM9 Lawrence Street Combined Sewer Separation*1,800 $2,826,000 $500K $1,163K $1,163K
SM10 Suitcase Pipe Replacement on Washington Street 303 $399,000 $399K
SM11 Long-Term Sewer System Investigation and Refurbishment**--$56,000,000 $56,000K**
SM12 Water Street Sewer Replacement 1,600 $2,100,000 $2,100K
$80,284,000 $2,350K $1,855K $2,019K $1,513K $350K $5,333K $66,864K
WW1 $5,000,000 $500K $4,500K
WW2 $300,000 $300K
WW3 $1,000,000 $50K $50K $50K $50K $50K $250K $500K
WW4 $6,300,000 $1,100K $3,200K $2,000K
$12,600,000 $1,450K $3,250K $2,050K $50K $550K $4,750K $500K
F1 $2,120,000 $300K $1,820K
F2 $1,200,000 $1,200K
F3 $1,250,000 $1,250K
F4 $1,250,000 $1,250K
F5 $120,000 $60K $60K
F6 $1,140,000 $150K $990K
F7 $630,000 $630K
F8 $2,940,000 $100K $400K $2,440K
F9 $4,000,000 $500K $600K $2,900K
F10 $3,000,000 $3,000K
F11 $2,000,000 $2,000K
F12 $30,000,000 $30,000K
$49,650,000 $860K $4,670K $4,580K $0K $400K $9,140K $30,000K
C1 $890,000 $160K $365K $365K
C2 $700,000 $150K $130K $130K $130K $160K
C3 $460,000 $460K
C4 $390,000 $390K
C5 $80,000 $19K $19K $19K $23K
C6 $410,000 $15K $395K
C7 $670,000 $100K $285K $285K
C8 $300,000 $300K
$3,900,000 $479K $974K $594K $803K $495K $160K $395K
M1 $90,000 $90K
M2 $2,850,000 $100K $2,750K
M3 $250,000 $250K
M4 $250,000 $250K
$3,440,000 $0K $440K $0K $0K $0K $2,750K $250K
$149,874,000 $5,139K $11,189K $9,243K $2,366K $1,795K $22,133K $98,009K
*50% cost shown in the CIP table. It is assumed an additional 50% will be paid by the Road and Storm Drainage departments.
**Costs are budgetary for pipe replacement of unknown materials. As the City video inspects the system and updates condition, this is subject to change. Rate analysis only includes anticipated grants to reduce City expenditure to $21 million.
Compost Screen Replacement
Solids Handling Tank Replacement and Mechanical Upgrades
Wastewater Treatment Facility Improvements
Mill Lift Station
Existing Monroe Street Lift Station Improvements
Sewer Camera Van, Video Camera and Tractor, Recording Software and Hardware, and Staff Training
Total - Lift Station Improvements
General Lift Station Improvements
Influent Pump Station and Odor Control Improvements
Headworks Rehabilitation
Clarifier No. 2 Improvements
Compost Facility and Solids Handling Improvements
Solids Handling Influent Screening and Grit Removal
Electrical Upgrades
Outfall Upgrades
Clarifier No. 1 Improvements
Howard Street and S Park Avenue
Sims Way, 3rd Street, and Gise Street
Total - Sewer Main Improvements
Lift Station Improvements
Howard Street, S Park Avenue, and McPherson Street
Sewer System Defect Investigation and Repair
Holcomb Street
Project Description
Sewer Main Improvements
Sims Way Crossing and Wilson Street Realignment
Compost Case Loader Replacement
Public Works Shop - Sewer Collection Share
General Sewer Plan Update
Total - Miscellaneous Improvements
Total Estimated Project Costs of City-funded Improvements
Compost Blowers Replacements
Compost Facility Infrastructure Upgrades
6-inch Hydrant Line
Office with Dedicated Lunchroom
Total - Facility Improvements
Miscellaneous and Planning Improvements
Arc Flash Analysis
Downtown Restrooms
Near-Term Oxidation Ditch Improvements
Non-Potable Water Pump Replacements (City to Install)
SCADA Upgrades
Total - Facility Improvements
Land Acquisition for WWTF Expansion
Long-Term WWTF Expansion (Budgetary Estimate)
On-Site Solids Handling Improvements
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Esri, HERE,
Garmin,
USGS, EPA
WW1
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SM6
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SM10
SM7
SM5
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SM3
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SM1
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SM6
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SM9
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SM4
SM7
Island County, WA State Parks GIS, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA,
NPS, US Census Bureau, USDA
DRAWING IS FULL SCALE
WHEN BAR MEASURES 2”
0 1,000 2,000500
Feet
1 inch : 2,000 Feet
Legend
CIP Project Time to Completion
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Vicinity Map
This map is a graphic
representation derived from the
CLIENT Geographic Information
System. It was designed and
intended for CLIENT staff use only;
it is not guaranteed to survey
accuracy. This map is based on the
best information available on the
date shown on this map.
Any reproduction or sale of this
map, or portions thereof, is
prohibited without express written
authorization by the CLIENT.
This material is owned and
copyrighted by the CLIENT.
Chinese
Gardens
Kah Tai
Lagoon
Port Townsend Bay
Strait of Juan De Fuca
Admiralty Inlet
WW4
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11 | FINANCIAL ANALYSIS
INTRODUCTION
The financial analysis assesses the ability of the City of Port Townsend’s (City) sewer utility to
remain financially viable during the planning period, considering its recent historical performance
as well as anticipated future needs. It also evaluates the affordability of the City’s sewer rates, both
at existing levels and with any rate increases needed to support the planned capital program.
FINANCIAL HISTORY
The City tracks the financial activities of its water and sewer utilities in a set of joint funds .
• Water/Sewer Operating Fund (411)
• Water/Sewer Capital Fund (415)
• Olympic Gravity Water System Fund (417)
• Water/Sewer Debt Reserve Fund (430)
• System Development Charge Fund (495)
The City has historically recovered the cost of ongoing operations and maintenance through a
combination of base fees and volume fees, imposing a separate capital surcharge to recover costs
associated with debt service and capital investment. Though the City originally introduced the
capital surcharge in 2013 to communicate the rate impacts of major capital projects to ratepayers,
it has decided to consolidate it into the “main” rate structure to recognize that capital investment
is an ongoing obligation of the City’s sewer utility. As a result, this analysis includes capital
surcharge revenue in the definition of “rate revenue.”
Table 11-1 summarizes the financial performance of the City’s sewer utility from 2018 through
2023, given its allocated share of revenues, expenses, and reserve balances from each of the funds
listed above. Key findings include:
• Though the City historically transferred utility taxes directly to its General Fund, it began to
account for utility tax revenue in Fund 411 in 2019. Excluding the impacts of this change in
accounting practices, the City’s sewer rate revenue increased by about 10 percent from
2018 to 2023. Most of this increase is attributable to the City’s decisions to increase its
sewer base fees and volume fees by a total of approximately 9 percent during this period.
The remainder can be explained by recent growth in the City’s sewer customer base ;
• Excluding the impacts of the City’s change in utility tax accounting practices, t he sewer
utility’s operating expenses increased by about 38 percent from 2018 to 2023. Inflation
likely contributed significantly toward this increase, as the Consumer Price Index for the
Seattle-Tacoma-Bellevue area increased by 26 percent during this period. In addition, labor
costs, including salaries and benefits, have increased at a rate exceeding inflation;
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Table 11-1
Summary of Historical Financial Performance ($000s)
Fund Resources and Uses Arising from 2018 2019 2020 2021 2022 2023
Cash Transactions – Sewer Utility Share Actual Actual Actual Actual Actual Budget
Beginning Cash & Investments ($000s) $2,160 $1,803 $2,288 $3,142 $4,057 $4,767
Operating Revenues
Intergovernmental $ - $ - $ 0 $ 0 $ - $ -
Rate Revenue 2,626 3,168 3,080 3,251 3,414 3,450
Other Charges for Services 258 285 190 200 198 222
Miscellaneous 3 10 8 10 13 2
Total ($000s) $2,886 $3,463 $3,279 $3,461 $3,625 $3,675
Operating Expenses
General Government $ 221 $ 217 $ 228 $ 0 $ - $ -
Utility Operations 1,885 2,527 2,477 2,911 3,067 3,456
Total ($000s) $2,106 $2,743 $2,704 $2,911 $3,067 $3,456
Net Operating Income (Loss) $780 $720 $575 $550 $558 $219
Operating Ratio 1.37 1.26 1.21 1.19 1.18 1.06
Other Increases (Decreases) in Fund Resources
Capital Revenues 19 544 396 495 617 259
Custodial Activities (Net) (1) - - - - -
Debt Proceeds - - 189 - 2 -
Net Transfers In (Out) (236) (90) 32 115 743 (8)
Debt Service (168) (167) (113) (119) (64) (52)
Capital Expenditures (751) (484) (224) (126) (1,175) (339)
Net Other Resources (Uses) 0 (38) - - 28 -
Net Change in Fund Position ($000s) (357) 485 855 915 710 80
Ending Cash & Investments ($000s) $1,803 $2,288 $3,142 $4,057 $4,767 $4,847
Days of Cash on Hand 313 304 424 509 567 512
• The operating ratio provides a means of evaluating the self-sufficiency of the City’s sewer
utility as an enterprise, measuring the ability of annual operating revenues to cover annual
operating costs. A ratio of 1.0 indicates that the City’s sewer utility is collecting exactly
enough revenue to pay for its operating costs. Table 11-1 indicates that while the sewer
utility was generally able to cover its operating expenses from 2018 to 2023, there was a
net cash flow deficiency in 2018 for the sewer funds overall after capital expenditures and
interfund transfers had been covered; and
• Days of cash on hand is a measure of financial security, quantifying how long the City’s
sewer utility would be able to fund daily operating and maintenance costs if it rec eived no
additional revenue. It is calculated by dividing unrestricted cash by the average daily cost of
operations. While there is no formal minimum standard for this metric, bond rating
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agencies have recently expressed a preference for a minimum of 180 days of cash on hand
for utilities seeking the highest bond ratings. Considering its operating and capital reserves,
the sewer utility maintained over 300 days of cash on hand between 2018 and 2023.
CAPITAL FUNDING RESOURCES
Other than cash financing, the City may fund the sewer Capital Improvement Plan (CIP) from a
variety of sources, described in further detail below.
Grant and Low-Cost Loan Programs
Historically, federal and state grant programs were available to local utilities for capital funding
assistance. However, these assistance programs have been mostly eliminated, substantially
reduced in scope and amount, or replaced by loan programs. Remaining miscellaneous grant
programs are generally lightly funded and heavily subscribed. Nonetheless, th e benefit of
low-interest loans makes the effort of applying worthwhile. Appendix N includes a document
published by the Washington State Department of Commerce that outlines state programs,
eligibility requirements, and contact information.
System Development Charges (SDCs)
SDCs are a form of connection charge authorized in Revised Code of Washington (RCW) 35.92.025.
The City imposes SDCs on development seeking to connect (or upsize an existing connection) to its
sewer system as a condition of service, and are in addition to any other costs of connection.
Typically based on a blend of historical and planned future capital investment in system
infrastructure, the underlying premise is that growth (future customers) will pay for growth-related
costs that the utility has incurred (or will incur) to provide capacity to serve new customers. The
key components of the SDC calculation are described below.
• Existing Cost Basis: The SDC recovers a proportionate share of the cost of existing assets
from growth. City records indicate a cumulative investment of $26.7 million in existing
assets.
• Interest: RCW 35.92.025 allows up to 10 years of interest accrued on existing assets to be
included in the cost basis. Based on the original cost and acquisition date of the sewer
utility’s assets, the SDC cost basis includes $14.9 million in interest .
• Future System Costs: The SDC recovers a proportionate share of costs associated with
future capital projects from growth to recognize that growth either directly drives or
otherwise benefits from these projects. Table 10-3 indicates a total projected capital cost of
$115.7 million in 2023 dollars – the SDC cost basis is adjusted to exclude $6.8 million in
costs that the City expects to fund with grants and other sources external to the sewer
utility on the premise that the SDC should only recover a share of the investment made in
the sewer system by the utility and its ratepayers. In addition, the SDC calculation deducts a
provision for future asset retirements to recognize that certain projects in the CIP will
replace existing assets. This adjustment intends to avoid double charging development for
an asset and its replacement concurrently, recognizing that the assets added through the
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CIP will generally cost more than the historical acquisition costs of the existing assets. Based
on the projected cost of replacement projects and the expected life of the facilities being
replaced, the estimated provision for asset retirements is $3.6 million.
• System Capacity: The City imposes sewer SDCs based on water meter size as a
representation of how much wastewater a connection could generate, using
meter-and-service equivalent (MSE) ratios published by the American Water Works
Association (AWWA) to assign equivalent residential units (ERUs) to each meter size.
(AWWA also publishes equivalency ratios based on maximum continuous flow capacity,
which the City uses to assign ERUs to water service connections – because water meters are
often sized to meet demands that do not enter the sewer system, such as irrigation and fire
flow, the City’s SDC methodology uses MSEs to assign sewer ERUs.)
The SDC analysis estimates the ERU capacity of the sewer system by:
1. Estimating the number of existing ERUs using utility billing records. Based on a
current inventory of sewer customers by meter size, the City serves an estimated
4,781 ERUs;
2. Estimating the average flow/loading contributions per ERU using influent data from
the City’s wastewater treatment plant. An average of 2016 to 2021 data suggests
that an ERU contributes 174 gallons per day (gpd) of flow on an annual average
basis, 216 gpd of flow on a maximum month basis, 0.54 pounds per day of maximum
month 5-day Biochemical Oxygen Demand, and 0.55 pounds per day of maximum
month total suspended solids; and
3. Equating the design capacity of the wastewater treatment plant to an equivalent
number of ERUs, given the constraining measure of capacity. Based on the unit
flows/loadings summarized above, the wastewater treatment plant can
accommodate an estimated 6,673 ERUs based on annual average daily flow capacity
of 1.44 million gallons per day.
Table 11-2 summarizes the sewer SDC calculation.
Table 11-2
Sewer SDC Calculation
Sewer SDC Cost Basis ($000s)
Existing Assets as of 12/31/22 $ 26,685
Plus: Estimated 2023 Expenditures (Net of 50% Grant Funding) 300
Less: Estimated Cost of Assets Being Retired Through CIP Projects (3,567)
Plus: Interest on Existing Assets 14,905
Future Capital Projects (2023 Dollars) 115,128
Less: Projects Funded by Grants or External Contributions (6,796)
Net SDC Cost Basis $146,655
System Capacity in ERUs 6,673
Maximum Sewer SDC per ERU $21,978
Table 11-2 indicates that the City could justify increasing its sewer SDC to $21,978 per ERU.
Recognizing that such a high SDC could adversely impact growth in the City’s service area and
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contradict the City’s objective to encourage the development of affordable housing, the City
adopted the following changes effective April 1, 2024 (Ordinance 3330):
• Increasing the sewer SDC from $3,758 to $5,258 per ERU based on inflation in the
Engineering News-Record Construction Cost Index (20-City Average) from 2013 (when the
SDC had last been updated) to 2023. The financial plan assumes that beginning in 2025, the
City will adjust the sewer SDC annually for inflation.
• Establishing an alternate methodology for assigning ERUs to single-family connections
based on house size (excluding garages). Parcel data from the Jefferson County Assessor
informed the proposed structure, which includes five tiers based on square footage:
Residential – Single-Unit and Mobile Home
House Size in Square Feet (SF) Number of ERUs SDC
Up to 750 SF 0.36 $1,871
751 – 1,500 SF 0.70 $3,676
1,501 – 1,900 SF 1.00 $5,258
1,901 – 2,600 SF 1.30 $6,819
Larger Than 2,600 SF 1.90 $10,011
Bonds
While general obligation bonds pledge the full faith and credit of the issuing entity, revenue bonds
are typically secured by utility revenues. With this limited commitment, revenue bonds normally
bear higher interest rates than other types of debt and also require additional security conditions
intended to protect bondholders from default risk. These conditions may include the maintenance
of dedicated reserves and minimum standards of financial performance (e.g., debt service
coverage).
Revenue bonds can be issued in Washington State without a public vote. While there is no explicit
statutory bonding limit, the conditions that come with revenue bonds often impose practical limits
on a utility’s level of indebtedness. An excessive debt burden may reduc e a utility’s flexibility to
phase in rate increases, also resulting in a higher overall cost of capital investment given the related
interest payments. It is worth noting that bond rating agencies also consider a utility’s debt service
coverage when assigning a rating – higher levels of indebtedness make it more difficult for a utility
to meet the coverage ratios that the rating agencies require for the highest ratings (and the lowest
interest rates). In recent years, these coverage ratios have often exceeded the minimum legal
standards outlined in the applicable bond covenants.
CURRENT REVENUE
The primary goal of the financial analysis is to develop a viable financial plan to support execution
of the planned capital projects while funding ongoing operation s and maintaining affordable rates.
This study defines the amount of revenue needed to meet the system’s financial obligations
including:
• Operation and maintenance costs;
• Administrative and overhead costs;
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• Policy-based needs (e.g., reserve funding);
• Capital costs; and
• Existing/new debt service obligations.
The City operates its sewer utility as an enterprise, relying on revenue from its sewer rates (as
opposed to taxes or other external resources) to cover the expenses outlined above. The
rate-setting process includes both operating and capital elements.
Financial Policies
The ensuing discussion summarizes the key financial policies used in this analysis.
Utility Reserves
Reserves are a key component of any utility financial strategy, as they provide the flexibility to
manage variations in costs and revenues that could otherwise have an adverse impact on
ratepayers. The financial analysis separates resources into the following funds:
• Operating Reserve: Providing an unrestricted cash balance to accommodate the short-term
cycles of revenues and expenses, these reserves are intended to address variations in
revenues and expenses (including anticipated variations in billing/receipt cycles, as well as
unanticipated variations due to weather or economic conditions). The financial analysis
assumes a minimum balance target of 60 days of operating expenses for this reserve, which
based on projected 2024 operating expenses equates to about $725,000.
• Capital Reserve: Providing a source of cash for emergency asset replacements or capital
project overruns, this reserve enforces an appropriate segregation of resources restricted or
designated for capital purposes. This analysis does not include a minimum balance for this
reserve, assuming that the City would be able to delay or seek external funding for capital
projects as needed.
• Bond Reserve: Bond covenants establish reserve requirements as a means of protecting
bondholders against the risk of nonpayment. While the City’s sewer utility does not
currently have outstanding debt that requires such a reserve, the forecast assumes a
minimum balance equal to one year’s debt service payment for future revenue bonds.
Recognizing that revenue bonds will likely be needed to fund at least part of the projected capital
costs, this analysis also targets a combined unrestricted cash balance (including both operating and
capital reserves, but not restricted bond reserves) of 180 days of operating expenses. Though not a
formal requirement, this policy is based on recommendations from the bond rating agencies for
borrowers seeking to optimize their bond ratings. Given the near-term expense forecast, the
combined target balance would be roughly $2,178,000 in 2024.
Financial Performance Standards
The financial plan (revenue requirement analysis) uses a pair of sufficiency tests to establish the
amount of revenue needed to meet the annual financial obligations of the City’s sewer utility.
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• Cash Flow Test: To satisfy this test, operating revenues must be adequate to fund all known
cash requirements, including operations and maintenance (O&M) expenses, debt service,
rate-funded capital outlays, and reserve funding.
• Coverage Test: Though the sewer utility currently has no debt requiring coverage, the
financial analysis assumes that the utility’s net revenue would need to be greater than or
equal to 1.25 times annual parity debt service (based on the requirements typically outlined
in bond covenants) in the event of future debt issuance.
The annual revenue requirement is broadly defined as the amount of revenue needed to satisfy
both of these tests. Short-term cash flow deficits may occur as part of a strategy to phase rate
increases in, as long as the utility has sufficient reserves on hand to absorb them ; however, any
applicable debt service coverage requirements must always be met.
Capital Funding Plan
As shown in Table 11-3, the sewer utility’s 20-year CIP includes $115.1 million in project costs (in
2023 dollars) with $51.9 million expected to occur in the next 10 years (2024 to 2033). Based on
input from City staff, the financial plan assumes construction cost inflation of 5 percent for 2024
and 4 percent per year thereafter. Adjusting for inflation, Table 11-3 shows a total 20-year capital
expenditure of $180.1 million, of which $63.8 million is projected to occur within the next 10 years.
Note that Table 11-3 only includes $21.3 million of the $56.0 million estimated for the long-term
sewer system refurbishment program – due to financing constraints, the remainder will either need
to be funded by grants or delayed beyond the 20-year period.
Shown in further detail in Table 11-4, the capital funding plan for the 10-year CIP (2024 to 2033)
consists of the following components:
• $6.3 million in grant funding, including $4.1 million for the Mill Road Lift Station,
$1.2 million for the Lawrence Street Combined Sewer Separation, and $1.1 million for the
Water Street Sewer Replacement (in addition to $300,000 in grant funding attributable to
2023 expenditures on the Water Street project).
• $483,000 in funding from the City’s Equipment Rental & Replacement (ERR) Fund f or the
purchase of a new screen for the City’s Compost Facility (the ERR Fund is an internal service
fund of the City that is external to the sewer utility).
• $1.1 million in Public Works Trust Fund loans for the Water Street Sewer Replacement. At
an interest rate of 0.86 percent, the annual payment on this loan (including an additional
$300,000 attributable to 2023 expenditures on this project) would be about $80,000.
• A $4.5 million State Revolving Fund (SRF) loan for the outfall upgrades. At an interest rate of
1.2 percent, the annual payment on this 20-year loan would be about $253,000.
• $30.9 million in revenue bond proceeds to fund various capital projects over the 10 -year
planning period. With interest rates of 3.5 to 4.0 percent, the annual payment on these
20-year bonds would increase to $2.3 million by the end of the planning period.
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• $2.0 million in Local Facilities Charges imposed on properties in the area benefitting from
the Mill Road Lift Station at the time of connection.
• $18.6 million in sewer utility cash resources, including $3.1 million in SDCs and $15.5 million
of cash contributions generated through rates.
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Table 11-3
Capital Cost Forecast
Capital Project Expenditures ($000s) 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 Future Total
Sewer Main Improvements
Sims Way Crossing & Wilson Street
Realignment $ 100 $ 606 $ 506 $ - $ - $ - $ - $ - $ - $ - $ - $ 1,212
Howard Street & South Park Avenue - - - - - - - - 400 1,178 - 1,578
Sims Way, Third Street, & Gise Street - - - - - - - - 300 886 - 1,186
Holcomb Street - - - - - - - - 150 669 - 819
Howard St., South Park Ave, & McPherson
St. - - - - - - - - - - 2,463 2,463
West Sims Way & 3rd Street - - - - - - - - - - 1,679 1,679
Future Interceptor Upsizing - - - - - - - - - - 6,722 6,722
Sewer System Defect Investigation &
Repair 150 350 350 350 350 350 350 350 350 350 - 3,300
Lawrence Street Combined Sewer
Separation - 500 1,163 1,163 - - - - - - - 2,826
Suitcase Pipe Replacement on
Washington St. - 399 - - - - - - - - - 399
Long-Term Sewer System Refurbishment - - - - - - - - - - 21,250 21,250
Water Street Sewer Replacement 2,100 - - - - - - - - - - 2,100
Lift Station Improvements
Existing Monroe St. Pump Station
Improvements - - - - 500 1,000 3,500 - - - - 5,000
Sewer Camera Van, Video Camera, &
Tractor 300 - - - - - - - - - - 300
General Lift Station Improvements 50 50 50 50 50 50 50 50 50 50 500 1,000
Mill Road Lift Station 1,100 3,200 2,000 - - - - - - - - 6,300
Wastewater Facility Improvements
Influent Pump Station & Odor Control
Improvements 300 1,820 - - - - - - - - - 2,120
Headworks Rehabilitation - - - - - 100 500 600 - - - 1,200
Clarifier No. 1 Improvements - - - - - 150 475 625 - - - 1,250
Clarifier No. 2 Improvements - - - - - 150 475 625 - - - 1,250
NPW Pump Replacements 60 - 60 - - - - - - - - 120
SCADA Upgrades - 150 990 - - - - - - - - 1,140
Electrical Upgrades - - 630 - - - - - - - - 630
Near-Term Oxidation Ditch Improvements - 100 - - 400 150 1,072 1,222 - - - 2,944
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Table 11-3
Capital Cost Forecast (Continued)
Capital Project Expenditures ($000s) 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 Future Total
Outfall Upgrades 500 600 2,900 - - - - - - - - 4,000
Onsite Solids Handling - - - - - 200 1,300 1,500 - - - 3,000
Land Acquisition for WWTP Expansion - 2,000 - - - - - - - - - 2,000
Long-Term WWTP Expansion - - - - - - - - - - 30,000 30,000
Compost Facility & Solids Handling
Improvements
Solids Handling Influent Screening & Grit
Removal - - 160 365 365 - - - - - - 890
Solids Handling Tank Repl. & Mechanical
Upgrades - 150 130 130 130 32 32 32 32 32 - 700
Compost Screen Replacement 460 - - - - - - - - - - 460
Compost Case Loader Replacement - 390 - - - - - - - - - 390
Compost Blower Replacements 19 19 19 23 - - - - - - - 80
Compost Facility Infrastructure Upgrades - 15 - - - - - - - - 395 410
6-Inch Hydrant Line - 100 285 285 - - - - - - - 670
Office with Dedicated Lunchroom - 300 - - - - - - - - - 300
Miscellaneous & Planning Improvements
Arc Flash Analysis - 90 - - - - - - - - - 90
Public Works Shop (Sewer Collection
Share)
- 100 - - - - - - - 2,750 - 2,850
General Sewer Plan Update - - - - - - - - - - 250 250
Downtown Restrooms - 250 - - - - - - - - - 250
Total (2023 Dollars) $5,139 $11,189 $ 9,243 $2,366 $1,795 $2,182 $ 7,754 $5,004 $1,282 $5,915 $ 63,259 $115,128
Total Projected Expenditures (with
Inflation)
$5,396 $12,218 $10,497 $2,795 $2,205 $2,787 $10,302 $6,914 $1,842 $8,840 $116,270 $180,067
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Table 11-4
Capital Funding Strategy
Capital Reserve Projections ($000s) 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2024-2033
Total
Beginning Balance $ 259 $ 5,019 $11,309 $2,783 $ 1,502 $10,948 $9,786 $1,648 $4,273 $5,924 $ 259
Plus: Interest Earnings 4 75 170 42 23 164 147 25 64 89 802
Plus: Grants – Mill Lift Station Project 1,000 3,100 - - - - - - - - 4,100
Plus: Grants – Lawrence Street Sewer
Separation Project - - 581 582 - - - - - - 1,163
Plus: Grants – Water Street Sewer
Replacement 1,050 - - - - - - - - - 1,050
Plus: PWTF Loan – Water Street Sewer
Replacement 1,050 - - - - - - - - - 1,050
Plus: SRF Loan – Outfall Upgrades 4,474 - - - - - - - - - 4,474
Plus: Revenue Bonds - 14,200 - - 10,100 - - 6,600 - - 30,900
Plus: ERR Reserves – Compost Screen
Replacement 483 - - - - - - - - - 483
Plus: Transfer from Operating Fund 1,552 570 637 288 903 813 1,644 2,534 3,040 4,233 16,216
Plus: Transfer from SDC Fund 344 363 382 403 425 448 173 180 188 197 3,103
Plus: Local SDC for Mill Road Lift Station Project 200 200 200 200 200 200 200 200 200 200 2,000
Less: Capital Expenditures (5,396) (12,218) (10,497) (2,795) (2,204) (2,787) (10,302) (6,914) (1,842) (8,840) (63,796)
Ending Balance $5,019 $11,309 $ 2,783 $1,502 $10,948 $9,786 $ 1,648 $4,273 $5,924 $1,803 $1,803
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Revenue Requirement
The revenue requirement analysis evaluates the sewer utility’s ability to cover its projected costs
under its currently adopted rates. In the event of any projected deficiencies, this analysis will serve
as the basis for a strategy of recommended rate revenue adjustments.
Projected Financial Performance
The revenue requirement analysis is developed from the City’s adopted 2023 Budget with other
assumptions:
• The forecast of sewer rate revenue is based on 2023 budgeted revenue provided by the
City, adjusted for customer growth. Based on the forecast of the City’s sewered population
presented in Table 3-3, the analysis assumes growth of about 1.4 percent per year (the
long-term annual average growth rate) through 2029 and 0.5 percent annual growth
thereafter. These projections are somewhat lower than the population projections
presented in Table 3-3, recognizing the difference between conservatism for financial
planning and conservatism in system planning. As previously noted, the projection of “rate
revenue” reflects the consolidation of the capital surcharge into the “main” sewer rate
structure;
• Interest earnings are calculated on the sewer utility’s projected fund balances assuming an
annual interest earnings rate of 1.5 percent;
• The operating forecast generally holds most of the sewer utility’s other operating revenues
at 2023 levels moving forward;
• The forecast of operating expenses generally adjusts the 2023 budgeted expenditures for
inflation assuming 5.0-percent inflation for 2024 and 4.0-percent inflation thereafter.
Though lower than recent inflation observed in the Consumer Price Index, these inflation
assumptions intend to recognize longer-term inflationary trends while maintaining a
reasonable degree of conservatism; and
• Taxes are calculated based on the projected revenues and prevailing rates:
o City Utility Tax: 16.0 percent;
o State Excise Tax (Sewer): 3.852 percent; and
o Business & Occupation (B&O) Tax: 1.75 percent.
Table 11-5 summarizes the sewer utility’s projected financial performance and rate revenue needs.
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Table 11-5
Projected Financial Performance and Revenue Requirements ($000s)
2024 2025 2026 2027 2028 2029 2030 2031 2032 2033
Revenue
Rate Revenue at 2023 Rates $3,072 $3,114 $3,156 $3,199 $3,243 $3,287 $3,304 $3,321 $3,337 $3,354
Other Operating Revenues 237 237 237 237 237 237 237 237 237 237
Use of Fund 430 for Debt Service 18 83 873 - - - - - - -
Total Revenues $3,327 $3,433 $4,266 $3,436 $3,480 $3,524 $3,541 $3,558 $3,574 $3,591
Expenses
Operating Expenses $4,417 $4,061 $4,210 $4,364 $4,525 $4,692 $4,812 $4,985 $5,165 $ 5,351
Debt Service 69 335 1,421 1,421 1,420 2,230 2,230 2,229 2,758 2,758
Direct Funding for Capital Projects - - - - - - 169 - - 2,627
Additions to Operating Reserve - - 24 25 26 27 20 29 29 31
Total Expenses $4,487 $4,397 $5,655 $5,810 $5,971 $6,949 $7,231 $7,243 $7,952 $10,767
Net Cash Flow ($1,160) ($964) ($1,389) ($2,374) ($2,491) ($3,425) ($3,690) ($3,685) ($4,378) ($7,176)
Annual Rate Increase 39.7%1 13.0% 13.0% 13.0% 13.0% 13.0% 13.0% 13.0% 13.0% 13.0%
Rate Revenue After Rate Increases $3,986 $4,915 $5,630 $6,449 $7,387 $8,462 $9,609 $10,913 $12,393 $14,074
Net Cash Flow After Rate Increases ($411) $512 $662 $313 $930 $841 $1,495 $2,563 $3,070 $1,637
Debt Coverage After Rate Increases (N/A) (N/A) 1.62 1.98 2.54 1.92 2.19 2.59 2.46 2.96
Projected Ending Balances (Sewer Share)
Operating Fund $ 726 $ 668 $ 692 $ 717 $ 744 $ 771 $ 791 $ 819 $ 849 $ 880
Capital Fund 5,019 11,309 2,783 1,502 10,948 9,786 1,648 4,273 5,924 1,803
Total $5,745 $11,977 $3,475 $2,220 $11,692 $10,558 $2,439 $5,093 $6,773 $2,683
Combined Balance as Days of O&M 475 Days 1,076
Days 301 Days 186 Days 943 Days 821 Days 185 Days 373 Days 479 Days 183 Days
1. The 2024 rate increase reflects the consolidation of the capital surcharge into the “main” sewer rate, targeting a 13.0% incr ease over the total existing sewer bill.
Table 11-5 indicates that at 2023 rates, the City’s sewer revenues are insufficient to cover the
sewer utility’s expenses – with inflation, projected increases in debt service, and capital funding
needs, the cash-flow deficiency generally grows larger over time (except in 2025, when total
operating expenses are expected to decrease after accounting for several one-time expenses built
into the 2024 projections). Table 11-5 shows a strategy of 13.0-percent annual rate increases from
2024 to 2033, which are projected to enable the sewer utility to cover the projected needs while
maintaining a combined fund balance of at least 180 days of operating expenses. The City Council
passed Ordinance 3332 at its February 20, 2024, meeting, adopting the rate increases for 2024
(effective April 1, 2024) through 2028 – the City intends to revisit the sewer financial plan in 2028
and assess whether the rate increases shown for 2029 and future years are still needed given any
capital funding assistance (e.g., grants, low-cost loans, forgivable principal loans) that the City is
able to obtain.
CURRENT AND PROJECTED SEWER RATES
The City imposes a two-tiered base rate on residential users, with residences using more than
3,000 gallons paying a higher base rate than those using 3,000 gallons or less. Multi -family,
commercial, and governmental users pay a base rate based on their water meter size and a volume
rate per thousand gallons of water usage. Effective April 1, 2024, the City eliminated the capital
surcharge and increased the rest of the sewer rate structure proportionately to maintain reven ue
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neutrality. Table 11-6 shows the sewer rate schedule adopted by the City Council on
February 20, 2024.
Table 11-6
Sewer Rate Forecast
Sewer Rate Structure
(Including Utility Tax)
Jan-Mar
2024
Apr-Dec
2024 2025 2026 2027 2028
Monthly Base Rate
Residential (Including Duplexes)
Usage ≤ 3,000 Gallons $46.46 $63.36 $71.60 $80.91 $91.42 $103.31
Usage > 3,000 Gallons $57.44 $78.33 $88.51 $100.02 $113.02 $127.71
Multi-Family/Commercial/Government:
5/8” – 3/4” Meter $41.18 $56.16 $63.46 $71.71 $81.03 $91.57
1” Meter $61.77 $84.23 $95.18 $107.56 $121.54 $137.34
1-1/2” Meter $102.94 $140.37 $158.62 $179.24 $202.55 $228.88
2” Meter $157.84 $215.24 $243.23 $274.84 $310.57 $350.95
3” Meter $576.48 $786.12 $888.32 $1,003.80 $1,134.29 $1,281.75
4” Meter $645.11 $879.72 $994.08 $1,123.31 $1,269.34 $1,434.35
6” Meter $960.80 $1,310.22 $1,480.55 $1,673.02 $1,890.51 $2,136.28
8” Meter $1,317.67 $1,796.87 $2,030.46 $2,294.42 $2,592.69 $2,929.74
Volume Rate per 1,000 Gallons
Multi-Family (3+ Units) $4.73 $6.45 $7.29 $8.24 $9.31 $10.52
Commercial A (2” or Smaller Meter) $6.38 $8.70 $9.83 $11.11 $12.55 $14.18
Commercia B (3” or Larger Meter) $4.18 $5.70 $6.45 $7.28 $8.23 $9.30
Government $6.24 $8.51 $9.62 $10.87 $12.29 $13.88
Capital Surcharge per Month
Standard $9.00 - - - - -
Low-Income $4.50 - - - - -
Utility Rate Affordability Analysis
A key objective of this financial chapter is to evaluate the City’s ability to execute the planned
capital improvement projects while maintaining reasonable sewer rates. Recognizing that a holistic
assessment of rate affordability must consider the total ut ility bill, Table 11-7 shows a forecast of
combined utility bills under the adopted rates for a residential customer using 3,000 gallons of
water per month.
The City has historically offered citizens with income levels at or below 150 percent of the poverty
level (PL) for Jefferson County a 50-percent discount on their water base charge (excluding volume
charges), their sewer charge, and their stormwater charge. Effective April 1, 2024, the City replaced
its low-income discount program with an income-based discount program consisting of the
following tiers:
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Income Level Discount to Water Base Charge, Sewer Charge, and Stormwater Charge
> 350% of PL 0% (Customer Pays 100% of Charges)
300% – 350% of PL 25% (Customer Pays 75% of Charges)
200% – 300% of PL 50% (Customer Pays 50% of Charges)
≤ 200% of PL 75% (Customer Pays 25% of Charges)
Table 11-7 shows the bills for residential customers using 3,000 gallons of water per month under
each of these income thresholds.
Table 11-7
Combined Utility Bill Forecast
Average Monthly
Residential Bill @ 3,000 Gallons
Jan-Mar
2024
Apr-Dec
2024 2025 2026 2027 2028
Income > 350% of PL
Water1 $ 70.84 $ 74.31 $ 76.86 $ 77.79 $ 80.90 $ 84.14
Sewer 55.46 63.36 71.60 80.91 91.42 103.31
Stormwater 16.89 20.05 22.01 24.41 27.02 29.62
Total $143.19 $157.72 $170.47 $183.11 $199.34 $217.07
Change from Prior Year +$14.53 +$12.75 +$12.64 +$16.23 +$17.73
Percent Change from Prior Year +10.1% +8.1% +7.4% +8.9% +8.9%
Income Between 300% – 350% of PL
Water1 (25% Discount to Base Charge) $ 70.84 $ 59.14 $ 61.14 $ 61.91 $ 64.39 $ 66.96
Sewer (25% Discount) 55.46 47.52 53.70 60.68 68.57 77.48
Stormwater (25% Discount) 16.89 15.04 16.51 18.31 20.27 22.22
Total $143.19 $121.70 $131.35 $140.90 $153.23 $166.66
Change from Prior Year ($21.49) +$9.65 +$9.55 +$12.33 +$13.43
Percent Change from Prior Year -15.0% +7.9% +7.3% +8.8% +8.8%
Income Between 200% – 300% of PL
Water1 (50% Discount to Base Charge) $ 70.84 $43.97 $45.43 $46.04 $ 47.88 $ 49.80
Sewer (50% Discount) 55.46 31.68 35.80 40.46 45.71 51.66
Stormwater (50% Discount) 16.89 10.03 11.01 12.21 13.51 14.81
Total $143.19 $85.68 $92.24 $98.71 $107.10 $116.27
Change from Prior Year ($57.51) +$6.56 +$6.47 +$8.39 +$9.17
Percent Change from Prior Year -40.2% +7.7% +7.0% +8.5% +8.6%
Income ≤ 150% of PL
Water1 (75% Discount to Base Charge) $42.40 $28.79 $29.72 $30.16 $31.37 $32.62
Sewer (75% Discount) 27.73 15.84 17.90 20.23 22.86 25.83
Stormwater (75% Discount) 8.27 5.01 5.50 6.10 6.76 7.41
Total $78.40 $49.64 $53.12 $56.49 $60.99 $65.86
Change from Prior Year ($28.76) +$3.48 +$3.37 +$4.50 +$4.87
Percent Change from Prior Year -36.7% +7.0% +6.3% +8.0% +8.0%
1. Assumes 4% inflationary increases for 2027 and 2028; the City has only adopted water rates through 2026.
While the term “reasonable” is relatively subjective in its definition, agencies that offer low-cost
loans to utilities often use an “affordability index” based on median household income (MHI) to
define a threshold beyond which utility rates impose financial hardship on ratepayers. The
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benchmark most often used in this evaluation is 4.5 percent of the median household income in
the relevant demographic area for the combined water/sewer bill. The 2022 American Community
Survey indicates a median income of $59,193 (in 2022 dollars) for households in the City of Port
Townsend – adjusting for increases in the state minimum wage from 2022 to 2024 (12.3 percent),
the equivalent 2024 median income level would be $66,505. Table 11-8 summarizes the
affordability evaluation of the City’s rates based on median household income.
Table 11-8
Monthly Utility Bill as a Percentage of Median Household Income
Jan-Mar
2024
Apr-Dec
2024 2025 2026 2027 2028
Water Bill @ 3,000 Gallons $ 70.84 $ 74.31 $ 76.86 $ 77.79 $ 80.90 $ 84.14
Sewer Bill @ 3,000 Gallons 55.46 63.36 71.60 80.91 91.42 103.31
Combined Monthly Water/Sewer Bill $126.30 $137.67 $148.46 $158.70 $172.32 $187.45
Annual MHI1 $66,505 $66,505 $69,166 $71,932 $74,809 $77,802
Combined Bill as Percent of MHI 2.3% 2.5% 2.6% 2.6% 2.8% 2.9%
1. Assumes that MHI increases annually with inflation at 4% per year.
Table 11-8 shows that the combined water/sewer bill at 3,000 gallons is expected to remain within
the range of 2.5 to 3.0 percent of MHI through 2028 – even without the assumed inflationary
adjustments to MHI, the combined bill would only reach about 3.4 percent of MHI by 2028. Though
the City’s rates could be considered “affordable” by this standard, t here has been a growing
consensus in the industry that median household income is of limited value in assessing the
impacts of utility rates on customers with income levels far below the area median. As discussions
about rate affordability continue to evolve, two alternative metrics have been gaining traction as
providing a more meaningful basis for evaluating affordability:
Hours at Minimum Wage (HM)
HM quantifies the amount of time that someone earning minimum wage (currently $16.28 per
hour in Washington State) would need to work in order to pay their combined water/sewer bill,
assuming that they use a “lifeline” volume of 50 gallons per capita per day (gpcd). Based on the
City’s average household size of 1.85 people, this assumption equates to just over 2,800 gallons per
month per household (for simplicity, this assessment rounds the usage level up to 3,000 gallons per
month). The literature discussing HM recommends 8.0 hours as a threshold for defining
“affordable” rates.
Affordability Ratio at the 20th Income Percentile (AR20)
AR20 expresses the combined water/sewer bill (at 50 gpcd) as a percentage of the net disposable
income (NDI) of a household in the 20th income percentile after accounting for the cost of food,
housing, power, healthcare, and taxes.
• Based on data from the American Community Survey, the estimated gross income of a
household at the 20th income percentile is about $25,113 (roughly $2,100 per month).
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• Based on data from the Bureau of Labor Statistics’ Consumer Expenditure Survey, the
estimated annual expenditures for the essential needs listed above add up to $20,605 for a
household of two and $15,852 for a household of three. Though it is somewhat
counterintuitive that a household of two would spend more than a household of three on
these essential needs, the Consumer Expenditure Survey data suggests that on average, a
household of three gets a greater tax refund than a household of two (possib ly due to
dependent tax credits) and spends less on healthcare despite spending more in most other
areas.
The parameters above suggest that the NDI for a household in the 20 th income percentile falls into
the range of $376 to $772 per month, depending on whether the expense estimates for the
two-person or three-person household (which is more common for households in Washington
State) are used. The literature discussing AR20 recommends 10.0 percent of NDI as a threshold for
“affordable” rates.
Both HM and AR20 focus specifically on the combined water/sewer bill and do not explicitly account
for stormwater charges. While this is possibly because residential stormwater charges have
historically been low compared to water and sewer charges, stormwater rate increases driven by
infrastructure investments and water quality improvements are at a point where they arguably
should be considered in an affordability assessment. It is reasonable to expect that the
methodology for determining these metrics (as well as the suggested affordability thresholds) may
evolve over time as a result of stormwater rate increases. With this caveat, Table 11-9 summarizes
the affordability analysis for low-income residents based on the current definitions of HM and AR20.
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Table 11-9
Rate Affordability Assessment Based on HM and AR20
Jan-Mar
2024
Apr-Dec
2024 2025 2026 2027 2028
Residential (Income > 350% of PL)
Monthly Water/Sewer Bill @ 3,000 Gallons $126.30 $137.67 $148.46 $158.70 $172.32 $187.45
Bill as HM (Target: ≤ 8.0 Hours) 7.8 Hours 8.5 Hours 8.8 Hours 9.0 Hours 9.4 Hours 9.8 Hours
Bill as % of NDI (AR20, Target: ≤ 10.0%) 16.4 –
33.6%
17.8 –
36.6%
19.2 –
39.5%
20.6 –
42.2%
22.3 –
45.8%
24.3 –
49.9%
Residential (Income Between 300 – 350% of PL)
Monthly Water/Sewer Bill @ 3,000 Gallons $126.30 $106.66 $114.84 $122.59 $132.96 $144.44
Bill as HM (Target: ≤ 8.0 Hours) 7.8 Hours 6.6 Hours 6.8 Hours 7.0 Hours 7.3 Hours 7.6 Hours
Bill as % of NDI (AR20, Target: ≤ 10.0%) 16.4 –
33.6%
13.8 –
28.4%
14.9 –
30.5%
15.9 –
32.6%
17.2 –
35.4%
18.7 –
38.4%
Residential (Income Between 200 – 300% of PL)
Monthly Water/Sewer Bill @ 3,000 Gallons $126.30 $75.65 $81.23 $86.50 $93.59 $101.46
Bill as HM (Target: ≤ 8.0 Hours) 7.8 Hours 4.6 Hours 4.8 Hours 4.9 Hours 5.1 Hours 5.3 Hours
Bill as % of NDI (AR20, Target: ≤ 10.0%) 16.4 –
33.6%
9.8 –
20.1%
10.5 –
21.6%
11.2 –
23.0%
12.1 –
24.9%
13.1 –
27.0%
Residential (Income ≤ 150% of PL)
Monthly Water/Sewer Bill @ 3,000 Gallons $70.13 $44.63 $47.62 $50.39 $54.23 $58.45
Bill as HM (Target: ≤ 8.0 Hours) 4.3 Hours 2.7 Hours 2.8 Hours 2.9 Hours 3.0 Hours 3.1 Hours
Bill as % of NDI (AR20, Target: ≤ 10.0%) 9.1 –
18.7%
5.8 –
11.9%
6.2 –
12.7%
6.5 –
13.4%
7.0 –
14.4%
7.6 –
15.5%
Projected Minimum Hourly Wage1 $16.28 $16.28 $16.93 $17.61 $18.31 $19.05
Monthly NDI of Household @ 20th Percentile2 $376 –
$772
$376 –
$772
$376 –
$772
$376 –
$772
$376 –
$772
$376 –
$772
1Assumes that minimum wage increases annually with inflation (assumed to be 4% per year) per RCW 49.46.020.
2Range based on two-person and three-person homes; remains the same since both income and expenses are assumed to increase with inflation.
Table 11-9 shows that under the City’s “standard” residential rate schedule (applicable to
customers with annual income above 350 percent of PL), the bill for a residential customer using
3,000 gallons per month generally exceeds the suggested affordability thresholds based on HM and
AR20. The City’s introduction of a new income-based discount program in April 2024 appears to
materially improve the affordability of rates for customers below 350 percent of PL. It is worth
noting that the estimated annual income for a household in the City at the 20 th income percentile
($25,113) represents approximately 123 percent of the 2024 Federal Poverty Guideline of $20,440
for a household of two – in Table 11-9, this household would fall into the lowest income category
(150 percent of PL).
Rate Burden (EPA Methodology)
The U.S. Environmental Protection Agency (EPA) has developed a method for evaluating the
household burden of utility rates associated with water utilities. The framework for measuring
household affordability and financial capability include:
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1. The Household Burden Indicator (HBI), defined as basic water service costs (includes water,
wastewater, and stormwater combined) as a percent of the 20th percentile household
income (i.e., the Lowest Quintile of Income (LQI) for the Service Area); and
2. The Poverty Prevalence Indicator (PPI), defined as the percentage of community households
at or below 200 percent of the Federal Poverty Level (FPL).
Table 11-10 summarizes the guidelines for evaluating the relative rate burden using the EPA’s
methodology.
Table 11-10
Summary of Rate Burden Evaluation Based on EPA Methodology
HBI – Water Costs as a
Percent of Income at LQI
PPI – Percent of Households Below 200% of FPL
≥ 35% 20 – 35% < 20%
≥ 10% Very High Burden High Burden Moderate-High Burden
7 – 10% High Burden Moderate-High Burden Moderate-Low Burden
< 7% Moderate-High Burden Moderate-Low Burden Low Burden
Rates are generally considered to be “high burden” if total basic water costs are a relatively high
percentage of household income for the LQI household, and a relatively large proportion of the
community households are economically challenged. However, if less than 20 percent of
households are below 200 percent of FPL, the community as a whole may be affluent enough to
pay for water at a relatively cost without it becoming a high burden (although some households
might still struggle). This approach also suggests that utility service may be highly burdensome and
unaffordable if a large proportion of the community’s households are below 200 percent of FPL,
even if water bills are a relatively low percent of LQI (the lower-left portion of Table 11-10).
City staff estimated that approximately 29.5 percent of households in the City have income levels
below 200 percent of FPL. Table 11-11 summarizes the evaluation of rate burden under the EPA
methodology.
CHAPTER 11 CITY OF PORT TOWNSEND GENERAL SEWER PLAN
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Table 11-11
Rate Burden Assessment Based on EPA Methodology
Jan-Mar
2024
Apr-Dec
2024 2025 2026 2027 2028
Annual Income at 20th Income Percentile1 $25,113 $25,113 $26,118 $27,162 $28,249 $29,379
Monthly Income at 20th Income Percentile1 $2,093 $2,093 $2,176 $2,264 $2,354 $2,448
Residential (Income > 350% of PL)
Monthly Water/Sewer Bill @ 3,000 Gallons $126.30 $137.67 $148.46 $158.70 $172.32 $187.45
Bill as % of Monthly Income @ 20th Percentile 6.8% 7.5% 7.8% 8.1% 8.5% 8.9%
Rate Burden Mod. Low Mod. High Mod. High Mod. High Mod. High Mod. High
Residential (Income Between 300 – 350% of PL)
Monthly Water/Sewer Bill @ 3,000 Gallons $126.30 $106.66 $114.84 $122.59 $132.96 $144.44
Bill as % of Monthly Income @ 20th Percentile 6.8% 5.8% 6.0% 6.2% 6.5% 6.8%
Rate Burden Mod. Low Mod. Low Mod. Low Mod. Low Mod. Low Mod. Low
Residential (Income Between 200 – 300% of PL)
Monthly Water/Sewer Bill @ 3,000 Gallons $126.30 $75.65 $81.23 $86.50 $93.59 $101.46
Bill as % of Monthly Income @ 20th Percentile 6.8% 4.1% 4.2% 4.4% 4.5% 4.7%
Rate Burden Mod. Low Mod. Low Mod. Low Mod. Low Mod. Low Mod. Low
Residential (Income ≤ 150% of PL)
Monthly Water/Sewer Bill @ 3,000 Gallons $70.13 $44.63 $47.62 $50.39 $54.23 $58.45
Bill as % of Monthly Income @ 20th Percentile 3.7% 2.4% 2.4% 2.5% 2.6% 2.7%
Rate Burden Mod. Low Mod. Low Mod. Low Mod. Low Mod. Low Mod. Low
1Assumes that minimum wage increases annually with inflation (assumed to be 4% per year) per RCW 49.46.020.
Table 11-11 shows that under the “standard” residential rate schedule (applicable to customers
with annual income above 350 percent of PL), the bill for a residential customer using 3,000 gallons
per month would be considered a “moderate-high” rate burden. The City’s introduction of the
income-based discount program in April 2024 appears to help alleviate the burden to an extent,
reducing it to the “moderate-low” level through at least 2028. Given the expected rate increases
shown in Table 11-5 for 2029 and future years, it is reasonable to expect that the rate burden may
shift to higher levels over time unless the City can secure additional grant funding for the capital
plan.
Table 11-11 (as well as Table 11-9) show affordability assessments under each of the levels in the
City’s income-based discount program to recognize that: (a) not all qualifying customers will enroll
in the program; and (b) customers with below-average income levels that exceed the
20th percentile might also be burdened by rates.
CONCLUSION
Table 11-5 indicates that the City will need to increase its sewer rates significantly in order to cover
projected debt service payments on debt issued to fund several of the City’s upcoming capital
projects. In addition to debt service, this rate strategy also considers the need to keep up with
rising operating costs. The recommended strategy envisions rate increases of 13 percent per year
and inflationary increases to the City’s sewer SDC to provide additional funds to offset system
capital costs.
CITY OF PORT TOWNSEND GENERAL SEWER PLAN FINANCIAL ANALYSIS
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The affordability assessment suggests that the City’s utility rates may impose a significant burden
on lower-income citizens. By expanding its rate discount program, the City has taken a significant
step to alleviate the rate burden for customers that qualify for and enroll in the program.
Though the City Council has adopted sewer rates through 2028, the City may be able to reduce
future rate increases if it is successful in obtaining additional funding assistance for its capital
program. It would be prudent for the City to regularly monitor the financial position of its sewer
utility, revisiting the key underlying assumptions to ensure that the utility’s revenues remain
sufficient to meet its financial obligations.
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