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Home My WebLink About19-086 Amending the City’s Wastewater Plan by Replacing the Outfall Section of Chapter 7 of the Wastewater Comprehensive Plan and All of Chapter 8 of the Wastewater Facilities Plan with the 2019 Facility Plan Amendment for a New Off-Shore Outfall Resolution 19-086 Page 1 of 2 RESOLUTION NO. 19-086 A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF PORT TOWNSEND, WASHINGTON, AMENDING THE CITY'S WASTEWATER PLAN BY REPLACING THE OUTFALL SECTION OF CHAPTER 7 OF THE WASTEWATER COMPREHENSIVE PLAN AND ALL OF CHAPTER 8 OF THE WASTEWATER FACILITIES PLAN WITH THE 2019 FACILITY PLAN AMENDMENT FOR A NEW OFF-SHORE OUTFALL WHEREAS, in Resolution 02-032 the Port Townsend City Council adopted the City's Wastewater Plan consisting of two volumes: the Wastewater Comprehensive Plan and the Wastewater Facilities Plan; and WHEREAS, the City's National Pollution Discharge Elimination System (NPDES) permit requires that the City prepare and submit a facility plan amendment for a new wastewater outfall by December 31, 2018 and approvable plans and specifications by December 31, 2019, and the City has requested a one-year extension to these deadlines; and WHEREAS, the City hired CH2M HILL (currently operating as Jacobs Engineering)to complete a facility plan amendment and design for the new outfall; and WHEREAS, Jacobs Engineering completed an outfall facility plan in 2018 and has since performed additional field work and updates and prepared the 2019 Facility Plan Amendment; and WHEREAS, the facility plan is an amendment to the City's Wastewater Plan, specifically replacing the Outfall Section of Chapter 7 of the Wastewater Comprehensive Plan and replacing Chapter 8 of the Wastewater Facilities Plan. NOW, THEREFORE, BE IT RESOLVED by the City Council of the City of Port Townsend, Washington, as follows: The City of Port Townsend Wastewater Plan is amended by replacing the Outfall section of Chapter 7 of the Wastewater Comprehensive Plan and all of Chapter 8 of the Wastewater Facilities Plan with the 2019 Facility Plan Amendment for a New Off-Shore Outfall (Exhibit A to this Resolution). Resolution 19-086 Page 2 of 2 ADOPTED by the City Council of Port Townsend, WA at a regular meeting thereof, held this 4th day of November 2019. de.borah S Stip]:111 Mayor Attest: Approved as to form: Joanna Sanders, MMC lleiclar' l�v�r ac City Clerk City Attorney Resolution 19-086ExhibitA Page I of 537 2019 Facility Plan Amendment for a New Off-Shore Outfall Prepared for the City of Port Townsend Citynf Port , Townsend Prepared by J/�C4BS® September 2019 Resolution 19-086 Exhibit A Page 2 of 537 Resolution 19-086 Exhibit A Page 3 of 537 Contents 1. Introduction ....................................................................................................................................1 2. Background ........................................................................................Error! Bookmark not defined. 3. Updated Surveys in 2018 ..............................................................................................................1 4. Updated Water Quality Evaluation in 2018..................................................................................1 4.1 Reference to 2009 Water Quality Evaluation...................................................................... 1 4.2 Summary of Evaluation Methodology.................................................................................2 4.3 Key Elements of this Updated Water Quality Evaluation....................................................2 4.3.1 Water Quality Standards........................................................................................3 4.3.2 Actual, Field-Collected Water Quality Data Used in Evaluation ............................3 4.3.3 Dilution Modeling....................................................................................................4 4.3.4 Reasonable Potential Analysis (RPA) ...................................................................4 4.4 Summary of Results............................................................................................................4 4.4.1 Metals, Ammonia, and Total Residual Chlorine.....................................................4 4.4.2 Toxic Organics.......................................................................................................6 4.4.3 Conclusions............................................................................................................6 5. Implementation Schedule .............................................................................................................6 Tables Table 1. Summary of Wastewater Treatment Plant Effluent Data Evaluated .........................................3 Table 2. Summary of Results for metals, ammonia and total residual chlorine .....................................5 Attachments A Facility Plan Amendment to the City of Port Townsend's 2000 Wastewater Facilities Plan for a New Off-Shore Outfall B Overall Site Plan, dated August 2018 C North Beach Outfall Habitat Report dated 10/8/2018 D Excerpt from WAC 173-201A E Sampling Results for Organic Compounds F Reasonable Potential Analysis Worksheet Resolution 19-086 Exhibit A Page 4 of 537 Resolution 19-086ExhibitA Page 5 of 537 2019 Facility Plan Amendment .JACOBS 1 . Introduction This 2019 Facility Plan Amendment (FPA)for a New Off-Shore Outfall is an amendment to the City's Comprehensive Wastewater Plan, replacing the Outfall section in Chapter 7 of the Wastewater Comprehensive Plan and Chapter 8 of the Wastewater Facilities Plan. This 2019 FPA is also prepared to comply with WAC 173-240-060 (Engineering Report) and the supplemental requirements presented in Table G1-1 of the Washington State Department of Ecology's (Ecology's) Criteria for Sewage Works Design (Orange Book). This 2019 FPA incorporates the material from the draft Facility Plan Amendment (FPA) that was prepared by CH2M HILL in December 2009 (attached as Attachment A). The draft 2009 FPA was submitted to Ecology for review and approval, but it was never formally approved because the State Environmental Permit Approval (SEPA) process was not completed. The purpose of this 2019 FPA is to document the City's updated water quality analysis and planning efforts to replace the off-shore portion of its existing wastewater treatment plant outfall with a new outfall system and diffuser. The appendices and attachments to this FPA will become attachments to the City's Wastewater Plan. 2. Background Planning work on this project began in 2007 and continued through the end of 2009. The document in Attachment A is unchanged from what was submitted at the end of 2009; it is incorporated into the 2019 Plan Amendment as Attachment A. Attachments B through F to the e 2019 Facility Plan Amendment are new material since the 2009 draft Plan. 3. Updated Surveys in 2018 In 2018, the design consultant's sub consultants collected additional eelgrass and surf grass survey data, bathymetry data, and kelp data. The eelgrass and surf grass survey showed the distribution of eelgrass and surf grass were similar to the survey preformed in 2008. The updated eelgrass and surf grass survey is shown in Attachment B in relation to the eelgrass and surf grass survey from 2008, which also indicates the proposed new outfall location. The updated bathymetry is also shown in Attachment B, which has not changed much since the 2008 survey. The reconnaissance kelp survey showed that within the project area the kelp is dense and abundant. Attachment C, The North Beach Outfall Habitat Report, outlines reconnaissance level survey data and results on macroalgae (primary kelp, surf grass and eelgrass) relative to the proposed sewer outfall and the existing outfall locations. A reconnaissance kelp survey was undertaken at the request of Washington State Department of Fish and Wildlife (WDFW) and Washington State Department of Natural Resources (DNR) to assess the spatial relationship of the existing outfall to the local kelp habitat. The City's current proposed outfall alignment and diffuser location is the same as what was proposed in the 2009 draft FPA and is also presented in Attachment B. 4. Updated Water Quality Evaluation in 2018 This section presents an evaluation of compliance with Washington State Surface Water Quality Standards (Washington Administrative Code [WAC] 173-201 A)for the proposed replacement outfall. 4.1 Reference to 2009 Water Quality Evaluation An evaluation of compliance with Ecology's water quality standards was completed as part of the 2009 draft FPA, refer to Attachment A. A majority of the required state water quality standards that were analyzed for this proposed project as part of the 2009 draft FPA have remained unchanged. Since 2009, state water quality standards for a number of pollutants have been newly promulgated or revised, including cadmium, nickel, and a number of toxic organics. Also, since 2009, the WWTP has collected new effluent water quality data per the City's NPDES permit requirements. The purpose of this updated evaluation is to confirm that the location and configuration of the diffuser, as selected in 2009, remains adequate to enable compliance with the current Ecology water quality standards. Section 2 of the 2009 Resolution 19-086ExhibitA Page 6 of 537 JACOBS 2019 Facility Plan Amendment draft FPA(Attachment A) present discussion of the water quality evaluation and Section 6.1 summarized how the City's dilution analysis and diffusor design meets the water quality standards. The detailed evaluation can be found in Appendix B of Attachment A to this 2019 draft FPA, the 2009 draft FPA. 4.2 Summary of Evaluation Methodology The summary presented here expands upon Section 2 of the 2009 draft FPA(Attachment A) and identifies the key methods necessary to assess compliance by the new outfall with state water quality standards. State water quality standards must be met at a certain distance from an outfall diffuser, which are the mixing zone boundaries. There are two types of mixing zone boundaries which surrounds the outfall diffuse, the Acute Mixing Zone (AZB) and the Chronic Mixing Zone Boundary (MZB). The 2009 draft FPA, Section 2 (Attachment A) describes further detail on the mixing zone boundaries. Modeling is used to predict the amount of mixing (dilution)that occurs at that mixing zone boundary. Dilution modeling for the proposed replacement outfall was completed in 2009 and the results of the modeling is presented in Section 6.1 of the 2009 draft FPA. The use of the 2009 model-predicted dilutions was done in order to provide conservative conditions for both the AZB and the MZB. If the maximum probable discharge concentration at the outfall is less than the water quality standard required at the AZB and MZB, while accounting for any background concentrations, then compliance with the standards has been achieved. The model-predicted dilutions are used to compute the predicted water quality concentrations at the AZB and MZB. These predicted water quality concentrations must be less than the standards required at the AZB and MZB to demonstrate compliance. Refer to Table 2 Summary of Results below. The compliance evaluation presented herein is based on a required calculation approach that is referred to as a "reasonable potential analysis," or RPA. An RPA is a calculation used to determine whether a facility's discharge has a "reasonable potential"to cause or contribute to a violation (exceedance) of water quality standards. The RPA calculation is based on the procedures outlined in the U.S. Environmental Protection Agency's (EPA) 1991 Technical Support Document For Water Quality-based Toxics Control as well as Ecology's Water Quality Program Permit Writer's Manual(Ecology Publication no. 92-109, Revised January 2015). The RPA calculation incorporates the required water quality standards, actual field-collected data, and dilution factors. The RPA calculation for this evaluation was completed using Ecology's "PermitCalc" spreadsheet tool (version 11/22/2016). 4.3 Key Elements of this Updated Water Quality Evaluation To predict compliance with state water quality standards, the following key criteria were necessary and implemented to complete this evaluation. These include: • Water Quality Standards. These are the required pollutant concentrations upon which compliance is determined. • Actual, Field-Collected Water Quality Data. These are the data that are required to be collected per the City's current NPDES permit. • Dilution Modeling. Dilution modeling predicts the rate of dispersion of pollutants in an effluent discharge. In doing so, it enables compliance for pollutants in the effluent stream that exceed the required water quality standards. • Reasonable Potential Analysis (RPA). Ecology's "PermitCalc" spreadsheet tool (version 11/22/2016) was used to implement this required calculation approach. Discussion of these criteria are presented in the subsections below. Resolution 19-086 Exhibit A Page 7 of 537 2019 Facility Plan Amendment .JACOBS 4.3.1 Water Quality Standards The current water quality standards that apply to outfalls discharging to waters of the state are presented in WAC 173-201A-240. The entire WAC 173-201A-240 is excerpted and included in Attachment D for reference. The City is not required to test for all of the pollutants regulated by WAC 173-201A-240 presented in Attachment D. The City is only required to test for pollutants identified in its NPDES permit, as prescribed by Ecology. Therefore, the City is not required to demonstrate compliance for the pollutants for which it is not required to monitor. 4.3.2 Actual, Field-Collected Water Quality Data Used in Evaluation The City's wastewater treatment plant effluent monitoring data from 2015 to 2018 was used in this evaluation. All of these data are available to the public on Ecology's online permit database (https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/W ater-quality-permits- database). In general, the maximum pollutant concentrations measured in the effluent have not changed substantially since the 2009 evaluation. For some pollutants, laboratory detection limits improved or changed such that a direct comparison between values from the 2009 evaluation and this updated evaluation is not entirely possible. A summary of the City's wastewater treatment plant effluent used in this evaluation is presented in Table 1. For each of the pollutants evaluated, the number of samples included in the evaluation and the maximum effluent concentration used in the evaluation are presented. Maximum effluent concentrations are the highest value taken from the City of Port Townsend samples (column three in Table 1) and the number of samples collected between 2015 to 2018 is listed in column 2 in Table 1. Table 1. Summary of Wastewater Treatment Plant Effluent Data Evaluated Number of Samples Collected, Maximum Effluent Concentration Pollutant Reviewed,and Included in Evaluation Used in Evaluation(pg/L) Antimony 3 1.0 Arsenic 3 1.2 Cadmium 3 0.3 Chromium(hexavalent) 3 10(undetected)a Copper 3 31.7 Lead 3 0.7 Mercury 3 0.002 Nickel 3 2.5 Selenium 2 0.3(undetected)a Silver 3 0.2(undetected)a Thallium 3 0.3(undetected)a Zinc 2 86.5 Ammonia 3 430 Total Residual Chlorine 971 30 b Toxic Organics(Total Phenolic 2 to 3 Varies(most undetected) Compounds,Volatile Organic Compounds,Acid-extractable Compounds,Base-neutral Compounds) a The pollutant was not detected in any of the samples;this value represents the maximum laboratory detection limit for the pollutant in the data set. b Value represents the 95th-percentile effluent concentration.The 96th-percentile value may be used when more than 10 samples have been collected and included in the evaluation. The maximum copper concentration in the effluent of 31.7 pg/L, reported in 2016, appears to be an outlier. A reasonable explanation for this outlier could be sample contamination. All other effluent copper Resolution 19-086ExhibitA Page 8 of 537 JACOBS 2019 Facility Plan Amendment concentrations since 2005 are below 10 pg/L. However, this high value was still used in this updated evaluation to provide confidence in the assessment of compliance. 4.3.3 Dilution Modeling The 2009 draft FPA presented model-predicted dilutions for the proposed diffuser for both existing discharge flows and ultimate build-out (far-future)WWTP effluent flows. Refer to Attachment A the 2009 draft FPA Appendix B Table 7b of for a detailed summary of the multi-model approach used to identify dilution factors for this (and the 2009) evaluation. A summary of the dilution factors used for the 2009 evaluation, based on the ultimate build-out flow conditions, are summarized in Section 6.1 of the 2009 draft FPA(Attachment A). These very conservative model-predicted dilutions from the 2009 draft FPA were also used for this updated evaluation. The diffuser site, design, and WWTP effluent flows have not been modified since 2009; therefore, it is appropriate to use the same dilution factors. Since 2009, average daily flows from the City's WWTP have shown a downward trend. As such, the 2009 draft FPA's model-predicted dilutions remain valid and representative of reasonable worst-case discharge conditions according to Ecology guidance. As presented in Section 6.1 of the 2009 draft FPA, the dilution factors are: • AZB (Acute Aquatic Life Criteria): 22 • MZB (Chronic Aquatic Life and Human Health Criteria): 99 4.3.4 Reasonable Potential Analysis (RPA) The RPA calculation calculates the predicted "Maximum Probable Discharge Concentration" at the mixing zone boundaries based on field-collected data, and multiplier factors that add an element of conservatism to the analysis. The RPA tool then calculates the estimated maximum concentration at the edge of the mixing zone boundaries, accounting for any background pollutant concentrations. Compliance with required water quality standards can be demonstrated if the Maximum Probable Discharge Concentration for a pollutant is less than the water quality standard, such that dilution is not required to achieve compliance at the mixing zone boundary. If that is not the case, the dilution factors modeled for the AZB and MZB can be used to show that the diluted concentrations of the actual field-collected pollutants are less than the applicable water quality standard. 4.4 Summary of Results The results of this water quality evaluation are presented in a tabular format for metals, ammonia, and total residual chlorine, refer to Table 2 below. The results of the evaluation of these pollutants indicate compliance with the required water quality standards. However, the evaluation of toxic organic pollutants is somewhat more complicated, and those results are presented in narrative format in Section 3.4.2 below. 4.4.1 Metals, Ammonia, and Total Residual Chlorine Table 2 presents a summary of the results of this water quality evaluation for metals, ammonia and total residual chlorine. Table 2 shows that only a few of the pollutants require dilution to meet water quality standards. Note that the water quality standards for copper are still met using the maximum effluent value of 31.7 pg/L, which as noted above, is likely an outlier. In summary, compliance with each of the required standards for metals, ammonia, and total residual chlorine are demonstrated by the results presented in Table 2. Resolution 19-086 Exhibit A Page 9 of 537 2019 Facility Plan Amendment .JACOBS Table 2. Summary of Results for metals, ammonia and total residual chlorine Water Quality after Dilution: Acute Chronic Human Maximum Probable Acute Chronic Human Dilution Needed to Water Quality Aquatic Life Aquatic Life Health Discharge Aquatic Aquatic Health Meet Water Quality Pollutant Criteria Criteria Criteria Concentration(ug/L)a Life Criteria Life Criteria Criteria Standard(s)? Met? Antimony -- -- 90 3.0 -- -- 0.012 No Arsenic a 69 36 -- 3.6 0.335 0.215 -- No -- -- -- 0.14 1.4 -- -- 0.015 Yes Yes Cadmium 42 9.3 -- 0.9 0.212 0.187 -- No Chromium 1,100 50 30 2.146 1.115 No (hexavalent) Copper 4.8 3.1 95.1 4.351 1.589 -- Yes Yes Lead 210 8.1 2.1 0.377 0.317 -- No Mercury a 1.8 0.025 -- 0.006 0.0002 0.0001 -- No -- -- 0.15 0.002 -- -- 0.000024 No - Nickel a 74 8.2 -- 7.5 1.235 1.005 -- Yes b Yes -- -- 100 3.0 -- -- 0.96 No Selenium 290 71 -- 1.1 0.052 0.011 -- No -- -- 200 0.5 -- -- 0.00462 No Silver 1.9 -- 0.6 0.920 0.937 -- Yes b Yes Thallium -- -- 6.3 0.4 -- -- 0.00365 No - Zinc a 90 81 -- 328 17.55 6.7 -- Yes Yes -- -- 1,000 130 -- -- 4.90 No Ammonia° 6,771 ° 1,0171 -- 1,290 591 131 -- Yes Yes Total 13 7.5 -- 30 1.364 0.303 -- Yes Yes Residual Chlorine 'The maximum probable discharge concentration calculation uses different multiplier factors for evaluating against aquatic life criteria and human health criteria. bAlthough the discharge concentration is below the standard(s),dilution still needed due to background pollutant concentrations in the receiving water. Unionized ammonia concentrations assumes an un-ionized fraction of 2.8%,which is calculated based on ambient receiving water temperature of 15 deg.C, pH of 8.1,and salinity of 29.97 practical salinity units(equivalent to parts per thousand). Resolution 19-086 Exhibit A Page 10 of 537 JACOBS 2019 Facility Plan Amendment 4.4.2 Toxic Organics The laboratory analysis results of the toxic organics, required per the City's NPDES permit to monitor, are presented in Attachment E. The vast majority of these pollutants were not detected at the laboratory detection limits. The few pollutants that actually detected are identified by the lack of a "less-than"symbol in the "Value Qualifier" column. The required water quality standards for many of these undetected pollutants was much greater than the associated laboratory detection limits, therefore, the pollutant was not evaluated further. The toxic organics with laboratory detection limits or measured values greater than the required water quality standards were evaluated using the required PermitCalc spreadsheet tool. The RPA spreadsheet tool is included as Attachment F. The standard RPA approach for pollutants that are not detected at the laboratory detection limit involves assuming they could be present at a concentration of half of the detection limit for that particular pollutant. Based on this approach, twelve toxic organic pollutants were predicted using the PermitCalc tool to exceed the required water quality standards. Note, however, that the detection limits required of the City per its NPDES permit do not enable demonstration of compliance. If the City were to analyze for these pollutants at laboratory lower detection limits, compliance with these required water quality standards could, in fact, be demonstrated. One toxic organic pollutant presents an apparent exceedance of the required water quality standard for different reasons. Using the PermitCalc tool, Bis(2-Ethylhexyl) Phthalate (BEHP) results in an exceedance of the current human health marine water quality standard. However, this pollutant is commonly detected as a byproduct of composite sampling practices, which incorporate the use of plastic tubing. These composite sampling practices are a requirement of the City's NPDES permit. The plastic tubing can contaminate the sample, resulting in a "false positive" for this pollutant. As such, we cannot conclude with confidence that the effluent is in fact causing a violation of water quality standards. Future sampling with an emphasis on clean sampling techniques, low detection limits, and quality control measures could demonstrate compliance for this chemical. 4.4.3 Conclusions The results summarized herein demonstrate that the proposed outfall can still achieve compliance with state water quality standards, similar to what was demonstrated in the 2009 evaluation. This is true even considering the additional and, in some cases, more stringent current water quality standards. 5. Implementation Schedule The City plans to complete design and permitting in 2020 and construction in 2021. Details related to the implementation schedule will be developed in the early stages of permitting, which is expected in early-to mid-2020. Resolution 19-086ExhibitA Page 11 of 537 Attachment A Facility Plan Amendment to the City of Port Townsend's 2000 Wastewater Facilities Plan for a New Off-Shore Outfall Resolution 19-086 Exhibit A Page 12 of 537 Resolution 19-086 Exhibit A Page 13 of 537 r AGENCY-RE R QpRT Ci aR AM:. A— Ir Qkr '.,�^- �..� .tip - • � �� . 4�„'~','• .1 I� � '- �� i ��- , i _ • - ` w .. w iI.* ► r - 4+ - - `s —f Resolution 19-086 Exhibit A Page 14 of 537 Resolution 19-086ExhibitA Page 15 of 537 FaCilitV PlanAmendment To the City of Port Townsend's 2000 Wastewater Facilities Plan for a New Off-Shore Outfall AGENCY-REVIEW DRAFT epRT?b 'ET 4 in = v u OP Prepared by CH2MHILL December 2009 Resolution 19-086 Exhibit A Page 16 of 537 Resolution 19-086 Exhibit A Page 17 of 537 FACILITY PLAN AMENDMENT Contents 1. Introduction......................................................................................................................1 1.1. Project Objective..................................................................................................1 1.2. Existing Outfall....................................................................................................1 1.3. Site Description....................................................................................................2 2. Description of Discharge Requirements.....................................................................2 3. Sensitive Habitat Conditions at Project Site..............................................................3 4. Future Conditions............................................................................................................4 5. Alternatives Evaluation..................................................................................................5 5.1. Preliminary Evaluation of Alternatives ...........................................................5 5.2. Evaluation of Installation Methods...................................................................5 5.3. Evaluation of Pipeline Materials.......................................................................6 6. Selected Alternative........................................................................................................8 6.1. Dilution Analysis and Diffuser Design............................................................8 6.2. Hydraulic Analysis .............................................................................................9 6.2.1. Analysis Conditions and Approach..................................................10 6.2.2. Results....................................................................................................11 6.2.3. Selection of Outfall Diameter.............................................................12 7. Estimated Costs..............................................................................................................12 8. Required Permits...........................................................................................................12 9. Anticipated Project Schedule......................................................................................13 Tables 1. Flow Data Used For Evaluating the Capacity of Proposed New Outfall System 2. Comparison of Required Dilutions with Dilution Performance 3. Estimated Concentrations at 50 Feet From Diffuser 4. Hydraulic Conditions 5. Estimated Gravity Capacity of New Outfall System 6. Summary of Estimated Project Costs 7. List of Permits and Approvals Anticipated to be Required Exhibits 1. Anticipated Project Schedule Figures (at end of body of report) 1. Location Map 2. Distribution of Eelgrass and Surfgrass and Proposed Outfall Diffuser Location PORT TOWNSEND WWTP FPA.DOC 111 DECEMBER 2009 Resolution 19-086 Exhibit A Page 18 of 537 FACILITY PLAN AMENDMENT Appendices A. Technical Memorandum: 2007 Outfall Condition Assessment--Port Townsend WWTP Outfall and Diffuser;November 30,2007 B. Technical Memorandum: Port Townsend WWTP Outfall Replacement Project: Diffuser Conceptual Design Evaluation;October 2009 C. Eelgrass/ Seagrass Surveys from 2007 and 2008 D. Technical Memorandum: City of Port Townsend WWTP Outfall Project: Evaluation of Repair/Replacement Alternatives;April 17,2008 E. Technical Memorandum: Evaluation of HDD as Installation Method;January 7,2009 F. Preliminary Design Drawings G. Detailed Breakdown of Construction Cost Estimate H. State Environmental Policy Act (SEPA) Checklist and Determination of Non-Significance (DNS) PORT TOWNSEND WWTP FPA.DOC v DECEMBER 2009 Resolution 19-086 Exhibit A Page 19 of 537 FACILITY PLAN AMENDMENT 1 . Introduction This Facility Plan Amendment (FPA) is prepared to comply with WAC 173-240-060 (Engineering Report) and the supplemental requirements presented in Table G1-1 of the Washington State Department of Ecology's (Ecology's) Criteria for Sewage Works Design (Orange Book). This FPA amends the City of Port Townsend's (City's) existing Wastewater Facilities Plan, dated November 2000. The purpose of this FPA is to address the City's ongoing proactive efforts to replace the off-shore portion of its existing wastewater treatment plant outfall with a new outfall system and diffuser. 1.1. Project Objective The City's wastewater treatment plant outfall has experienced several near-shore leaks in recent years and appears to be drawing near to its anticipated useful life expectancy. The purpose of this project is to replace the off-shore portion of the existing outfall system with a new outfall (including new diffuser) that is roughly parallel to the existing outfall. The new outfall will provide hydraulic capacity for current and projected effluent flows,will meet state water quality standards under defined critical conditions,and is located to minimize adverse construction and permanent impacts to near-shore sensitive habitat. This project follows in the wake of the City's replacement of the on-shore portion of the outfall system that was completed in 2005. The on-shore portion was replaced because of recurrent blockages caused by root-intrusion resulting in surcharging at maintenance holes along the outfall. While the primary reason for replacing the on-shore and off-shore portions of the outfall system are both related to their condition,an important secondary benefit of this project is expanded capacity to accommodate projected increases in future flows by gravity under varying tide conditions. Related to this secondary capacity benefit,the length of the off- shore outfall system(distance off shore)was determined in accordance with the Ecology's discharge standards,as discussed in Section 6.1,the diameter of the system was selected based on hydraulic analysis to assess the gravity capacity of the system in conjunction with the recently-replaced on-shore portion of the outfall. If additional outfall capacity is needed in the long-term future,the City will consider incorporating a low-head pump station at the upstream end of the outfall. However,this added element is not anticipated to be necessary until many years into the long-term future,if ever. 1.2. Existing Outfall The City's wastewater treatment facility is located on the north side of the City just inland from the Strait of Juan de Fuca. A key component of the outfall disposal system is the existing ocean outfall (off-shore) that extends 900 feet from shore into the Strait of Juan de Fuca. The existing outfall was originally installed in the 1940s or 1950s and then extended in the 1960s. The original outfall installation extended approximately 450 feet into the Strait using 3-foot lengths of 18-inch-diameter concrete pipe (commonly called"shorts'). In the late 1960s,the outfall was extended an additional 450 feet into the strait using 18-inch- diameter cast iron pipe in 18-foot lengths. The new cast iron section was connected to the older concrete pipe section, and a new cast iron diffuser was installed at the end of the extended outfall,approximately 900 feet offshore. PORT TOWNSEND WWTP FPA.DOC 1 DECEMBER 2009 Resolution 19-O86Exhibit A Page 20 of 537 FACILITY PLAN AMENDMENT The City's off-shore outfall has experienced several near-shore leaks in recent years and appears to be drawing near to its anticipated useful life expectancy. The condition of the existing off-shore outfall was assessed during the fall of 2007. The results of this detailed internal and external condition assessment included a recommendation for replacement of the outfall because of its deteriorating condition. A copy of the condition assessment is presented in Appendix A of this document. Dye testing showed leaks in the original concrete reach of the outfall in the near-shore portion. A visual inspection of the outside of the existing outfall was conducted by divers. While significant marine growth was observed on the unburied portions of the pipe,no further leaks were found in the stretch of cast iron pipe. Closed circuit television(CCTV) extending into the outfall from the nearest onshore clean out was conducted in 2005 by the City. The CCTV inspection revealed deposition of gravel in the cast iron reach significant enough in depth to halt the CCTV inspection. 1.3. Site Description The existing outfall extends northward into Admiralty Inlet from the City of Port Townsend's WWTP. The replacement outfall will be installed parallel and just to the west of the existing outfall by approximately 100 feet. The on-shore portion of the new outfall will be installed in City right of way and a County Park. The off-shore portion of the outfall will extend approximately 700 feet from shore and be installed in between,and partially among,existing surf grass and eel grass beds. The site and approximate outfall alignment is shown in Figure 1. 2. Description of Discharge Requirements The disposal of the City of Port Townsend's wastewater treatment plant effluent into the state's receiving waters must comply with the Washington State Surface Water Quality Standards (Washington Administrative Code [WAC] 173-201A) and be engineered to handle the range of existing and projected effluent flows. These water quality standards are based on the receiving water body type and its biological uses. These water quality standards define the distance from the discharge point for compliance. There are two zones that surround the discharge point,the zone of acute criteria exceedance (acute zone boundary or AZB) and the chronic mixing zone boundary (MZB). The acute criteria for the protection of aquatic life must be met at the AZB. The chronic criteria for the protection of aquatic life and human health-based water quality criteria must be met at the MZB. The MZB in Puget Sound is defined as 200 feet from the discharge point plus the water depth at Mean Lower Low Water (MLLW). The AZB is defined as 10 percent of the distance to the MZB. The City of Port Townsend routinely monitors its wastewater treatment plant effluent for the parameters specified in their NPDES permit. In addition,the City is required to periodically collect and test for metals and organics (including nutrients) that are not included in the NPDES permit. The combined effluent water quality data set collected by the City was used,as applicable,to establish the dilution required to comply with the water quality standards described above. PORT TOWNSEND WWTP FPA.DOC 2 DECEMBER 2009 Resolution 19-086 Exhibit A Page 21 of 537 FACILITY PLAN AMENDMENT There are acute and chronic water quality discharge standards for several of the metals for which the City has collected data. In addition,there are discharge standards related to ammonia and total residual chlorine. The proposed design and location of the outfall diffuser is based on complying with these water quality discharge standards. Where the City's wastewater treatment plant effluent concentration is greater than these water quality standards or where the detection limits for each of the constituents exceed the applicable standards, dilution requirements are established for the outfall diffuser. These dilution requirements are developed for acute and chronic aquatic criteria as well as human health criteria for each constituent using a reasonable potential analysis. The procedure for developing the reasonable potential analysis is defined in Section 3.3.2 of EPA's Technical Support Document for Water Quality-based Toxics Control and Ecology's Permit Writer's Manual. The reasonable potential analysis is designed to predict the effluent chemical concentrations at the 95th-percentile upper-bound confidence level (based on the maximum concentration measured in the existing samples data set). The data set used for development of the dilution requirements was collected between 2005 and July of 2009. A detailed discussion of the discharge requirements for this outfall replacement project is presented in Section 4 and Table 5 of the technical memorandum entitled"Port Townsend WWTP Outfall Replacement Project: Diffuser Conceptual Design Evaluation," which is presented in Appendix B of this document. The dilution requirements for each of the water quality constituents for which there is a standard are presented in Table 5 of the subject technical memorandum in Appendix B. What is clear from Table 5 is that the required dilutions to meet these standards (presented in the three columns on the right) range from zero to relatively low. A summary of the required dilutions are as follows: • For aquatic life at the AZB: 5:1 for copper and 4:1 for total residual chlorine • For aquatic life at the MZB: 7:1 for copper and 9:1 for mercury* • For human health at the MZB: 8:1 for arsenic*and 2:1 for mercury* *The required dilutions presented above for arsenic and mercury are based on minimum detection limits and not actual measured values. These constituents were not actually detected in the wastewater treatment plant effluent. The diffuser outfall design and location for this project were developed and modeled to predict the actual dilutions to be achieved at the AZB and MZB. The results of that work are presented in Section 6.1. 3. Sensitive Habitat Conditions at Project Site The proposed replacement outfall will be installed adjacent to,and in part,through sensitive seagrass (eelgrass and surfgrass)habitat. The alignment of the outfall was selected to minimize impact to this sensitive habitat. The distribution of seagrass was mapped on two separate occasions in 2007 and 2008. The combined results of those mapping efforts are presented in Figure 2 along with the alignment of the existing outfall and the alignment of proposed replacement outfall. Copies of the seagrass studies from 2007 and 2008 are presented in Appendix C of this document. PORT TOWNSEND WWTP FPA.DOC 3 DECEMBER 2009 Resolution 19-086 Exhibit A Page 22 of 537 FACILITY PLAN AMENDMENT A Seagrass Mitigation Plan that addresses restoration of impacts during construction will be developed in support of this project and submitted to the applicable agencies,as presented in Section 8 of this document,for review and approval. Other permit-related workproducts such as a Cultural Resources Report and a Biological Assessment are being developed to assess related impacts. These workproducts will be submitted under separate cover to applicable agencies and will be available for review in conjunction with this Facility Plan Amendment. 4. Future Conditions The City of Port Townsend's Wastewater Facilities Plan (Plan) was completed in 2000. The Plan estimates growth in population and corresponding effluent flows from the Wastewater Treatment Facility (Plant). The estimated increase in effluent flows developed in the Plan exceeds what has been observed in the years since. Estimated future Plant flows are important to this project because they provide a basis for the gravity flow capacity of the new outfall system- specifically providing a sizing criterion for the diameter of the proposed new off-shore portion of the outfall. The flow data used for evaluating the capacity of the proposed new outfall system are presented in Table 1. TABLE 1 Flow Data Used For Evaluating the Capacity of Proposed New Outfall System Flow Data From Facilities Plan Actual Flow Data(2006—2009) Ultimate Flow Types 2000 Buildout 2006 2007 2008 2009 Average Day 915,310 2,905,038 977,000 918,000 900,000 - Peak Hour 4,811,876 10,647,897 -- Peak Day -- 1,979,000 1,813,000 1,376,000 2,060,000 What is apparent from Table 1 is that actual Plant flows are less than what was predicted. It appears the City is no closer to approaching the"ultimate buildout" flow conditions that were predicted in the Plan. Average plant flows have been relatively flat since 1995 -based on historical data presented in the Plan and the actual data presented in Table 1. This is primarily due to two key factors: (1) an overall heightened consciousness related to using water efficiently (as has been commonly observed in Washington State over the past 10 to 15 years) and (2) on-going,periodic improvements within the system related to correcting infiltration and segregating non-sanitary-waste inflow sources. It is important to note that there is limited driving head between the existing Plant and the outfall system. This limited driving head restricts the capacity of the outfall system under gravity flow conditions,especially under high tides. For this reason,the gravity flow capacity of the proposed new outfall system will not be sufficient to meet the predicted ultimate buildout peak hour flow conditions at high tide conditions. The estimated gravity capacity of the outfall system,and discussion related to estimated future Plant flows,is presented in Section 6.2. It is important to note that the City's strategy for accommodating Plant flows that exceed the gravity capacity of the new outfall system is to install a pump station to provide the additional hydraulic head necessary to convey these potential future PORT TOWNSEND WWTP FPA.DOC 4 DECEMBER 2009 Resolution 19-O86Exhibit A Page 23 of 537 FACILITY PLAN AMENDMENT higher flows. This pumped strategy was developed at the time the on-shore portion of the existing outfall system was replaced. As stated previously,the likelihood that such a pump station will ever be needed is uncertain at best. What is clear is that based on historic development trends in the City of Port Townsend such a pump station would likely not be needed for many years. 5. Alternatives Evaluation The City's evaluation of rehabilitation/replacement alternatives is presented in the following three subsections based on how the evaluation process developed over time. 5.1. Preliminary Evaluation of Alternatives Several alternatives were evaluated to address the City's aging off-shore outfall pipeline. These alternatives were grouped into the following three major categories: No-Action Alternative,Repair/Rehabilitation Alternatives,and Replacement Alternatives. Specifically, the alternatives (and sub-alternatives) evaluated include: 1. No Action Alternative 2. In-Place Repair/Rehabilitation Alternatives - Removal of Deposited Gravel - Repair of Identified Leakage Points - Slip-Lining - Cast-In-Place Pipe (CIPP) - Pipe Bursting 3. Replacement Alternatives - Cut and Cover - Horizontal Directional Drilling (HDD) - Micro-Tunneling A technical memorandum summarizing the evaluation of these alternatives is presented in Appendix D of this document. The evaluation summarizes the rationale for the approach the City selected,which was to pursue a replacement alternative. The No Action alternative was deemed inappropriate for pursuit primarily because of the potential for environmental contamination and potential public health concerns. The In-Place Repair/Rehabilitation alternatives were not pursued further because they were either deemed technically infeasible, they didn't result in an effective long-term solution, or they resulted in reduced outfall gravity flow capacity. After determining to pursue a replacement alternative,the City moved forward with evaluating three alternative installation methods: cut and cover, HDD,and micro-tunneling. 5.2. Evaluation of Installation Methods As stated above,the three replacement alternatives are linked to three different methods of installing the outfall pipeline,cut and cover, HDD,and micro-tunneling. The technical memorandum included in Appendix D summarizes preliminary evaluation (prior to geotechnical evaluation) of these three alternative installation methods. Generally,these three alternative installation methods can be characterized as follows: PORT TOWNSEND WWTP FPA.DOC 5 DECEMBER 2009 Resolution 19-O86Exhibit A Page 24 of 537 FACILITY PLAN AMENDMENT • Cut and cover methods have a high likelihood of success but are likely to have the most environmental impact during construction • HDD could minimize construction impact to sensitive near-shore seagrass environments. However,as a trenchless approach,HDD is only feasible under favorable subsurface geologic conditions. • Micro-tunneling is estimated to be the most costly of the three replacement alternatives and is also only feasible under favorable subsurface geologic conditions. Prior to finalizing the evaluation of the three installation methods,a geotechnical evaluation of the site conditions was undertaken. The geotechnical data report for this project is presented as an appendix (Appendix B) to a technical memorandum summarizing an evaluation of HDD as a potential installation method. This technical memorandum is presented in Appendix E of this document. The technical memorandum in Appendix E focuses on HDD as an installation approach and not the other two installation methods because it was estimated to be less costly than micro- tunneling. If deemed feasible,it would be pursued in lieu of micro-tunneling. Cut and cover methods are not addressed in the subject technical memorandum because if HDD were deemed feasible,it would be pursued in lieu of cut and cover because it is potentially less environmentally impactful. Furthermore,it was understood that if HDD were deemed to be infeasible because of geotechnical conditions,micro-tunneling would similarly be deemed infeasible-resulting in cut and cover as the only remaining installation method to be pursued. As discussed in Appendix E,the results of the geotechnical evaluation revealed that subsurface conditions are not suitable for trenchless installation methods-whether by HDD or micro-tunneling. Surface and subsurface conditions in the project site are replete with cobbles and large boulders. Such subsurface conditions are not suitable for trenchless installation methods. As a result,trenchless installation methods were not pursued further. 5.3. Evaluation of Pipeline Materials After determining to pursue a cut and cover installation method, several alternative pipeline materials applicable to the cut and cover method were evaluated. These materials included: • Low head concrete • Prestressed concrete cylinder pipe • Ductile iron • High density polyethylene (HDPE) • PVC (bell& spigot joints or fusible) • Steel (cement coated and lined) Steel pipe using carnegie push on joints restrained with thrust collars and tie rods was selected as the pipe type for the proposed new outfall. This selection was based primarily on the following: • It is a high durability pipeline type. PORT TOWNSEND WWTP FPA.DOC 6 DECEMBER 2009 Resolution 19-O86Exhibit A Page 25 of 537 FACILITY PLAN AMENDMENT • It is heavy,will not float,and does not require concrete anchors to hold it in place once buried. • It is easy to install relative to other options. This pipe material can be equipped with thrust collars and tie rods that hold the joints together during installation and ensure that the joints are made with maximum stab depth. • While outfalls have been constructed over the years of a variety of materials, steel with a cement coating and lining has been shown to be a common and successful pipeline type for outfall installations. • While steel is inherently corrodible,the cement coating and lining provide an effective corrosion barrier. • Installation can be accomplished in relatively short open-trench sections and does not require a long section of trench to be held open. The reasons the other pipeline types were not selected and/or were not considered for further evaluation,include: • Low head concrete: This pipeline material is good with respect to corrosion resistance. However,this pipe type cannot be easily restrained using common methods. Not being able to restrain the pipe and ensure an effective pipe joint is maintained during installation makes this pipeline type undesirable. • Prestressed concrete cylinder pipe: This pipe type is essentially a lower-cost,lower-quality version of the pipe type selected. It uses a thin-walled steel pipe that is lined and coated with cement mortar. Prestressed wires are used in place of thicker-walled steel for the pipe cylinder. Because the cost of the pipe itself is relatively small with respect to the overall cost of the construction project,this pipeline type was not considered further. • Ductile iron: This is a high-quality,common pipe material that can be effectively restrained to ensure a good installation. However, ductile iron is not commonly coated with anything other than the thin asphaltic coating with which it comes standard. Without a high-quality cement mortar coating, this pipeline type is greatly compromised with respect to corrosion. As a result,it was not considered further. • High density polyethylene(HDPE): HDPE is attractive from a corrosion standpoint. Its biggest drawback is that it presents challenges being installed in a buried configuration in a non-quiescent environment. Because HDPE is installed as a completely-fused system,it must be assembled and fused on land and then floated into place and sunk into the trench. Doing so requires the trench to be excavated and maintained in a completely open position for an extended period of time. It is imprudent to rely on excellent weather and sea conditions to allow for an ideal installation. Without ideal conditions,installation of HDPE would be challenging,and the risk of damaging the pipe during installation great. • PVC (bell&spigot joints or fusible): PVC presents some attraction with respect to corrosion resistance. However, it presents challenges with respect to installation-in particular flotation. It is also not considered a durable pipe and could more likely be damaged PORT TOWNSEND WWTP FPA.DOC 7 DECEMBER 2009 Resolution 19-086 Exhibit A Page 26 of 537 FACILITY PLAN AMENDMENT during installation than other pipe materials. Similar to HDPE,it is susceptible to flotation. 6. Selected Alternative As presented in Section 5,the selected alternative for this project is to replace the off-shore portion of the existing outfall with a new,parallel off-shore outfall pipeline and diffuser. The new outfall pipeline will be installed by cut and cover methods. Steel,coated and lined with cement,will be the pipeline materials used. Preliminary design drawings of the proposed new outfall and diffuser are presented Appendix F of this document. The location of the diffuser with respect to its distance off-shore and submergence depth was determined by a dilution analysis that is presented in Section 6.1. The diameter of the outfall pipeline was determined by hydraulic analysis,as presented in Section 6.2. 6.1. Dilution Analysis and Diffuser Design The proposed location and configuration of the diffuser were determined based on worst- case site-specific current and water quality information for the receiving water as well as the water quality characteristics of the wastewater being discharged. Dilution modeling was completed to establish the predicted minimum dilutions from the new outfall diffuser. The proposed location of the outfall diffuser is shown in Figure 2 at a depth of approximately- 15 to-16 feet below MLLW,which is the location on which the drawings shown in Appendix F are based. This diffuser location was selected based on the results of the dilution modeling. Two optional diffuser sites were modeled in the vicinity of the anticipated location of the diffuser to somewhat bracket predicted dilutions in that vicinity. The development of results for two optional sites was arbitrary. The methods used for the dilution analysis,the results of the dilution analysis,and preliminary design configuration of the diffuser are presented in the technical memorandum entitled"Port Townsend WWTP Outfall Replacement Project: Diffuser Conceptual Design Evaluation," which is included in Appendix B of this document. The results of the dilution analysis are presented in Tables 7a and 7b of Appendix B. Table 7b presents the results of the proposed site for the new outfall diffuser. Predicted wastewater treatment plant effluent flow data from the 2000 Port Townsend Facilities Plan were used in the dilution modeling. It should be noted that these flow conditions represent predicted"ultimate buildout" conditions that are likely excessively conservative and are several times greater than any flows ever observed at the wastewater treatment plant. As stated in Section 2,there has been no increase in average wastewater treatment plant flow since 1995. The predicted dilutions presented in the last four columns of Table 7b are for ultimate buildout flow conditions. Two different models (DKHW and UM3) were used to predict dilution performance. The more-conservative results from the two models(UM3 results were more conservative) were used for comparison with the dilution requirements presented in Table 5 of Appendix B and summarized in Section 2 above. PORT TOWNSEND WWTP FPA.DOC 8 DECEMBER 2009 Resolution 19-O86Exhibit A Page 27 of 537 FACILITY PLAN AMENDMENT The predicted dilutions presented in Table 7b of Appendix B for ultimate buildout are summarized as follows: • For aquatic life at the AZB: 22:1 (the 10th percentile current velocity controls) • For aquatic life at the MZB: 99:1 • For human health at the MZB: 99:1 A comparison of the required dilutions summarized in Section 2 and the model-predicted dilutions summarized above are presented in Table 2. TABLE 2 Comparison of Required Dilutions with Dilution Performance(Model-Predicted Dilutions in Parentheses) Chemical Constituent AZB (22:1) MZB (99:1) Human Health (99:1) Copper 5:1 7:1 n/a Arsenic n/a n/a 8:1* Mercury n/a 9:1* 2:1* Total Residual Chlorine 4:1 n/a n/a Meets Required Dilutions yes Yes Yes *The required dilutions presented above for arsenic and mercury are based on minimum detection limits and not actual measured values. These constituents were not actually detected in the wastewater treatment plant effluent. The comparison presented in Table 2 shows that despite the very conservative effluent flow criterion used in the modeling,a very large margin of safety with respect to dilution will be provided by the new outfall diffuser. The predicted dilutions from the proposed new outfall diffuser will provide greater average (averages of the two models cited above) dilutions than those provided by the existing outfall diffuser. In addition to evaluating compliance with dilution requirements,as presented in Table 2, the dilution model was used to show estimated concentrations (maximum and average) of several key constituents of the City's wastewater treatment plant effluent at a distance of only 50 feet from the diffuser. These estimated concentrations are presented in Table 3. Copper and zinc are the only metals modeled because they are the only metals that were consistently measured above analytical detection limits. What is clear is that at a distance of 50 feet from the diffuser,the constituents presented in Table 3 (all except for Copper and Zinc do not have discharge standards) are essentially diluted to background levels,as reflected in the minor percent changes in receiving water for each constituent. 6.2. Hydraulic Analysis The proposed new outfall system was analyzed to estimate its gravity flow capacity and to select the diameter of the proposed new off-shore portion of the outfall. Three alternative diameters (18-,20-,and 24-inch)were considered for the new outfall pipeline. PORT TOWNSEND WWTP FPA.DOC 9 DECEMBER 2009 Resolution 19-086 Exhibit A Page 28 of 537 FACILITY PLAN AMENDMENT TABLE 3 Estimated Concentrations at 50 Feet From Diffuser Effluent Conc. (1) Plume Conc. at 50 feet from Diffuser(3) Receiving % Change in Constituent Maximum Average Water Conc.(2) Maximum Average Receiving Water Total Nitrogen 9.16 mg/L 5.32 mg/L 1.04-3.05 3.08 mg/L 1.06 mg/L 1.1%-2.2% Total 9.45 mg/L 7.1 mg/L 1.7-2.6 mg/L 2.64 mg/L 1.73 mg/L 1.5%- 1.8% Phosphorus Total Suspended 7.7 mg/L 3.9 mg/L 1 -6 mg/L 6.01 mg/L 1.02 mg/L 0.2%-2% Solids BODS 7.8 mg/L 4.9 mg/L <1.0 mg/L <1.0 mg/L <1.0 mg/L <1% pH 7.3 6.8 6.7-8.3 8.3 6.8 <1% Copper 9.5 ug/L 8.0 ug/L 0.8 ug/L 0.85 ug/L 0.84 ug/L 4%-5% Zinc 51 ug/L 49 ug/L 3.6 ug/L 3.86 ug/L 3.85 ug/L 7% (1) Effluent concentrations are based on Port Townsend WWTP effluent monitoring during 2005-2009. (2) Background marine water concentrations from Ecology's marine monitoring station ADM002 and Romberg,et.al,1984(dissolved metals). (3) Dilution modeling predicts that the average discharge plume dilution for the new diffuser at 50 feet will be 182:1 based on current average flows,and subsequent dilution and dispersion will continue to the mixing zone boundary and beyond. 6.2.1. Analysis Conditions and Approach The outfall system,which includes the existing, recently-replaced on-shore portion, extending from the chlorine contact basin at the Plant, as well as the new off-shore portion was analyzed at several tide conditions. The upstream and downstream hydraulic conditions used in the analysis,reflecting the water surface elevation at the chlorine contact basin and the tide conditions are presented in Table 4. TABLE 4 Hydraulic Conditions(feet) Elevation at Chlorine Contact Basin Effluent Chamber Tide Description Tide Elevation Available Driving Head 17.20(2) EHW 10.62 6.58 17.20 MHHW 7.41 9.79 17.20 MSL 3.88 13.32 17.20 MLLW -1.11 18.31 (1) Extreme High Water Elevation(EHW),Mean Higher High Water(MHHW),Mean Sea Level(MSL),Mean Lower Low Water(MLLW) (2) Actual elevation of the Chlorine Contact Basin effluent weir is 18.2 feet in NAVD88,as determined by survey measurements in December 2009. A high water elevation of one foot below the effluent weir was used to define the outfall system gravity capacity to avoid hydraulic impacts to upstream treatment process elements. PORT TOWNSEND WWTP FPA.DOC 10 DECEMBER 2009 Resolution 19-086 Exhibit A Page 29 of 537 FACILITY PLAN AMENDMENT The existing onshore reach of the outfall system consists of: • 140 feet of 24 inch ductile iron(DI) pipe extending from the chlorine contact basin at the wastewater treatment plant roughly to the treatment plant property line. This reach was installed with the treatment plant in the early 1990s. Hazen-Williams"C" factor for this reach of pipe was assumed to be 120. • 1,428 feet of 22-inch high density polyethylene (HDPE) pipe (DR 17) with an inside diameter of approximately 19.3 inches extending from the treatment plant property line to the beach. This reach was installed in mid to late 2005. Hazen-Williams"C" factor for this reach of pipe was assumed to be 140. As stated above,three different pipeline diameters (interior diameters)were analyzed for the 1,003 feet of the proposed new offshore outfall. The outfall pipe material is planned to be cement mortar coated and lined steel. The C factor used to reflect the mortar lining was 130. The diffuser was analyzed based on the proposed six 10-inch-diameter risers,each with a tide flex valve installed. Although the tide flex valves require driving head to open and have some impact on the capacity of the outfall system,they enhance the dispersion characteristics of the outfall and prevent sediment from entering and settling inside the diffuser. Head loss associated with the 10-inch tide flex valves were calculated using information provided by the manufacturer. 6.2.2. Results The estimated gravity capacity of the new outfall system is presented in Table 5 for the three pipeline diameters considered and for the four tide conditions considered. Implementing the new off-shore outfall as a 24-inch diameter pipeline as opposed to an 18-inch diameter pipeline (same as existing off-shore reach) significantly improves the overall hydraulic capacity of the system. Considering EHW conditions and the historical and projected flows presented in Table 5,the additional 1.18 mgd of gravity capacity provided by a 24-inch diameter pipeline as opposed to an 18-inch diameter pipeline could enable the City to defer implementation of an outfall pump station for many years. Implementing an outfall pipeline with a diameter larger than 24 inches would result in minimal additional capacity. This is because flow velocities are already relatively low in a 24-inch diameter pipe. TABLE 5 Estimated Gravity Capacity of New Outfall System(mgd) Diameter of New Off-Shore Outfall Tide Condition 18-inch Diameter 20-inch Diameter 24-inch Diameter EHW 4.27 4.86 5.45 MHHW 5.30 6.05 6.78 MSL 6.27 7.16 8.04 MLLW 7.46 8.52 9.56 PORT TOWNSEND WWTP FPA.DOC 11 DECEMBER 2009 Resolution 19-086 Exhibit A Page 30 of 537 FACILITY PLAN AMENDMENT 6.2.3. Selection of Outfall Diameter A 24-inch diameter pipeline was selected for the proposed 1,003 feet of new off-shore outfall. This selection is based on the substantial increase in capacity over 18-inch and 20-inch diameter sizes and because the increased cost of 1,003 feet of 24-inch diameter over the smaller sizes is relatively minor. The cost of installing pipelines off-shore is several times greater than similar on-shore construction,and it is very challenging to obtain the requisite environmental permits to construct off shore. The 24-inch diameter was selected to improve the chances of avoiding future replacement of the off-shore portion of the outfall system because of gravity capacity needs that might potentially arise. 7. Estimated Costs Estimated project costs for the new outfall are summarized in Table 6. A detailed breakdown of the estimated construction costs are presented in Appendix G of this document. The estimated construction cost was prepared in accordance with the guidelines of the AACE International, (the Association for the Advancement of Cost engineering) for a "Class 3 Estimate." According to the definitions of AACE International, a Class 3 Estimate is defined as being suitable to form the basis for project authorization and/or funding. Typically engineering is from 10% to 40% complete (30 percent in this case). This cost estimate identifies the necessary capital funding for this project based on the level of design completed to this point. Additional refinement of this cost estimate will be completed once more detailed design is completed. TABLE 6 Summary of Estimated Project Costs Cost Category Cost($) Preliminary Design and Study 330,000 Permitting-Related Activities 140,000 Detailed Design 110,000 Engineering Services During Construction 100,000 Non-Construction Subtotal 680,000 Construction Contract(incl. contingency and sales tax) 1,700,000 Seagrass Restoration (allowance) 200,000 Project Total 2,580,000 8. Required Permits Permits and approvals anticipated to be required for this project are presented in Table 7. The State Environmental Policy Act(SEPA) process is required to be completed prior to Ecology approval of Facility Plan and Engineering Report documents. A copy of the SEPA Checklist and the Declaration of Non-Significance for the SEPA process for this project is presented in Appendix H. PORT TOWNSEND WWTP FPA.DOC 12 DECEMBER 2009 Resolution 19-086 Exhibit A Page 31 of 537 FACILITY PLAN AMENDMENT TABLE 7 List of Permits and Approvals Anticipated to be Required Permit/Approval Process Granting/Lead Agency Comments SEPA City of Port Townsend SEPA declaration of non- significance is included in Appendix H Critical Areas Ordinance City of Port Townsend The Critical Areas Report is prepared under separate cover for submittal to the City of Port Townsend. JARPA Corps, Ecology,WDFW, City of JARPA is the application process Port Townsend that comprises several permit applications(as indicated below). Shoreline Substantial Development City of Port Townsend Part of JARPA. Permit Rivers and Harbors Act—Section 10 Corps Part of JARPA Clean Water Act-Nationwide Permit Corps Part of JARPA (Section 404) Endangered Species Act- Section 7 Corps, NMFS, USFWS Part of JARPA Consultation (Biological Assessment) Hydraulic Project Approval WDFW Part of JARPA Clean Water Act-Section 401 Water Ecology Part of JARPA Quality Certification Coastal Zone Management Act Ecology Part of JARPA Consistency Determination Aquatic Use Authorization DNR Part of JARPA Cultural Resources Survey Corps Part of JARPA NPDES General Construction Permit Ecology Stand-alone submittal for file(no review typically) NPDES Discharge Permit Ecology Separate, stand-alone application process 9. Anticipated Project Schedule Preliminary evaluation and study related to this project began in the summer of 2007 with the survey of the distribution of seagrass. Evaluation of alternatives,further study,and analysis has been completed since that time and continues to the present. This FPA reflects relevant work completed thus far related to this project. The anticipated project schedule for the remainder of this project is presented in Exhibit 1. It should be noted that monitoring of surfgrass restoration will likely last several years to confirm its success. PORT TOWNSEND WWTP FPA.DOC 13 DECEMBER 2009 Resolution 19-086 Exhibit A Page 32 of 537 FACILITY PLAN AMENDMENT Exhibit 1, Anticipated Project Schedule Task Name _ — -- __ -2010 _ _ 2011 Sep act'Nov i Dec Jan Feb Marl Pyx_ _Jul_Aug!Sep I Oct Nov Qec J9n Feb Mar Apr Mey Jun -Jul Auq Sep Oct Facility Plan Amendment 1011 Detailed Design Al2B 611D Ermfontnantal Pemittlog 11116 1�I28 foiling o1 C4n6lruptlon C4Mraol 119 3119 Construction Mobikxation,Plarwting,Prep- 3/16 7158 Cn•SNe Cmsv=lon ?MR*=-R022 Surlgr R"lomilon wa fir 9119 PORT TOWNSEND WWTP FPA.DOC 14 DECEMBER 2009 Resolution 19-086 Exhibit A Page 33 of 537 Figures Resolution 19-086 Exhibit A Page 34 of 537 Resolution 19-O86Exhibit A Page 35 of 537 U N O d O CCQ >a C 3: > O O -a N ++ C N J j O� r � CO L d O LL. a LL U c CE) 1 Z3 � o 1 CO 1 Y N O a O m N� 1 � � Ni6m a w N 7� O IL 1 `° 1 6 O I M p n 6 J �0 X 1 >OC7 7 0 0 0 O U H 0 N O 1 c O 1 0 N CO 'a N�Q < 57th Street - 1 d z o 0 1 LLI 0 I® a I U � N O IL m_ 1 in mo v — ww 1 I d z EH [I] N a+ EHc W 1 1 _� 1 � 1 IC a 1 -O 7 F 1 1 O z z -EHI-i F-H FF- ,E w 1 O 0 y 1 z N I w -EEI a � 1 1 a 53rd treet I J � U � F-IM ::1co zc G a C7, I y UC7� 1 F 1 I w =1 M M L �p �n 1 N � 1 � 0 1 0 F�] P F-I Wn I N 3 1 $ 0 1 w 1_ 49 ee - I o 1 0 1 a I O F 1 U 1 O LEl I i _ mra ree m Resolution 19-086 Exhibit A Page 36 of 537 Resolution 19-086 Exhibit A Pa e 37 of 537 C�C�C�C�C 0 50 100 150 Scale in Feet CD 7� , ? o a 1 i ALIGNM NT EXISTIN OU F L i b ` KUHN ST. ,o m OD 1 P AL ME OF NE OUT F ® ® J LO Ln p _ Ln LANDES ST. `—J LANDES 57e (VACATED) LEGEND `----------1 EELGRASS SURFGRASS Figure 2 OBSERVED DURING SURVEYS ON DISTRIBUTION OF EELGRASS AND SURFGRASS SEPTEMBER 17,2007&JUNE 16,2008. AND PROPOSED OUTFALL DIFFUSER LOCATION CH2MHILL Resolution 19-086 Exhibit A Page 38 of 537 Resolution 19-086 Exhibit A Page 39 of 537 Appendices Resolution 19-086 Exhibit A Page 40 of 537 Resolution 19-086ExhibitA Page 41 of 537 Appendix A Technical Memorandum: 2007 Outfall Condition Assessment -- Port Townsend WWTP Outfall and Diffuser; November 30, 2007 Resolution 19-086 Exhibit A Page 42 of 537 Resolution 19-086 Exhibit A Page 43 of 537 TECHNICAL MEMORANDUM CH2MHILL 2007 Outfall Condition Assessment -- Port Townsend WWTP Outfall and Diffuser PREPARED FOR: Mary Heather Ames,Project Manager, City of Port Townsend PREPARED BY: David Wilson, CH2M HILL Phil Martinez, CH2M HILL COPIES: John Merchant,Wastewater Superintendent, City of Port Townsend David Peterson, City Engineer, City of Port Townsend Kenneth Clow,Public Works Director, City of Port Townsend DATE: November 30, 2007 This technical memorandum presents the background, objectives, study approach,and results of CH2M HILL's outfall condition assessment of the Port Townsend Wastewater Treatment Plant(WWTP) outfall and diffuser. The assessment includes a detailed review of the June 2005 internal inspection videotape of the City of Port Townsend's outfall (shoreline to offshore),as well as the October 2007 external diving inspection of the outfall diffuser and outfall alignment(offshore to shoreline). Background The existing WWTP outfall is a relatively old structure that was constructed in two phases. In the 1940's the original outfall pipeline was constructed. The original outfall section extended 413 feet from the shoreline manhole to its terminal single port approximately 17 feet below Mean Lower Low Water (MLLW). The original outfall pipeline section was buried and consists of 3-foot reinforced concrete pipe segments (18-inch diameter) with bell and spigot connections -transitioning to cast iron at the original terminus. The limited available drawings indicate that the outfall terminated with an open ended 18-inch port at grade,and the outfall terminus was secured with a concrete block. This shallow single port outfall functioned for approximately twenty years until the City extended and improved the outfall in 1966. In 1966,the outfall pipeline was extended approximately 500 feet further offshore from the existing terminus. The buried outfall extension consisted of 18-foot section of Cl pipe with bell and spigot joints. The outfall extension was connected to the existing outfall terminus with a flex-coupling and anchor lugs. The outfall extension was designed to emerge from the seabed approximately 860 feet offshore of the shoreline manhole and terminate with a 36-foot long Cl pipe diffuser section. The outfall diffuser section is secured by two concrete anchor blocks that surround the pipe. The diffuser has four 6-inch ports that are situated on alternating sides of the pipe springline and one 6-inch terminal port that is located in the middle of the terminal flange. The design drawing shows two ports on each side of the diffuser with 9-foot spacing between ports,however,this inspection documented that the as-built configuration is different than the design. 1 Resolution 19-086 Exhibit A Page 44 of 537 PORT TOWNSEND WWTP OUTFALL AND DIFFUSER The nearshore (intertidal) outfall pipeline has shown leakage and failures that have led the City to repair several sections. The original 18-inch outfall pipeline from the treatment plant to the shoreline manhole was replaced in 2005 with 20-inch HDPE pipe by means of pipe- bursting. At that time,the shoreline manhole was relocated 15 feet upshore from the original site to remove it from the upper intertidal zone. The outfall length from the shoreline manhole to the outfall diffuser end is approximately 900 feet. Outfall Internal Inspection The City of Port Townsend (City) conducted an internal inspection of the offshore portion of the WWTP outfall pipe on June 30,2005. This internal inspection was performed using a video camera with lights mounded onto a track crawler that was inserted into the outfall at the beach manhole. The video camera and lights are capable of pivoting to allow a 360 degree view around the interior pipe wall. The internal inspection video was performed in two stages: stage 1 - shoreline to offshore (interior invert and sidewalls view),and stage 2- offshore to shoreline (interior crown view). For the first stage,the camera and lights were oriented to view forward and slightly downward to record the pipe invert and side-walls. For the second stage,the camera and lights were oriented to view upward and slightly forward. CH2M HILL has reviewed the internal inspection video record in detail and developed a summary of the findings to define problem areas and potential significant issues with the outfall operation and future use. Table 1 summarizes our review of the internal inspection video. Tables and figures are included at the end of thie technical memorandum. The internal inspection did not include the outfall diffuser section because the track crawler encountered a large accumulation of rocks that blocked passage approximately 40 feet from the outfall terminus. The following list summarizes the key aspects of the internal condition of the outfall: 1. Outfall invert contains substantial amount of gravels and rocks (small to large) that reduces the pipe volume by 5 to 15% along the pipe-essentially a continuous layer is present in the pipe from 117 feet offshore to 862 feet offshore (end of inspection); 2. Outfall invert contains some specific regions with accumulations of large (4-6") rocks that reduce pipe volume by 10 to +20% at the following offshore reaches;247 feet,621- 641 feet, 708-712 feet,and 855-862 feet; 3. Rock accumulation in the outfall invert at 862 feet had sufficient depth to block passage of the track crawler with camera (possibly >25%) and precluded internal inspection of diffuser length. Outfall joint offsets and discontinuities were noted at numerous joints in the older section of the outfall,but no clear joint failures were observed; 4. Outfall invert contains substantial growths (possible bacteria mats) on top of gravels and rocks that reduce the pipe volume (117 feet offshore to 862 feet offshore),and along the pipe side walls in certain reaches;and 5. Biological growth on the invert was populated with large numbers of white/gray worms (1-3 inch lengths) of unknown type. 2 Resolution 19-086 Exhibit A Page 45 of 537 PORT TOWNSEND WWTP OUTFALL AND DIFFUSER The outfall blockage with gravels and rocks presents a hydraulic constraint to high effluent flows. The large rocks could potentially be transported into the diffuser section where they could eventually plug diffuser ports and restrict effluent discharge. Outfall and Diffuser External Inspection On October 16 and 17,2007, CH2M HILL performed an external inspection of the WWTP outfall and diffuser to document its external integrity and function. This work included visual inspection and video taping of the exposed outfall diffuser section and the seabed along the outfall alignment. The external inspection also included the injection of tracer dye into the treated wastewater effluent and the use of an instrument to detect the presence of the tracer along the buried outfall alignment to detect leakage from the outfall. Photographs of the diffuser and seabed along the outfall alignment are presented in Attachment A. The outfall inspection video record is provided on a DVD disc that accompanies this memorandum in Attachment B. The key objectives for this outfall external inspection include: • Document the exposed outfall pipe conditions and functionality; • Document the location of the outfall terminus,diffuser length,and other exposed features; • Conduct surveillance along the outfall length to locate potential pipeline leaks;and • Record pipe corrosion features for evaluation by CH2M HILL's corrosion specialist. Field Methods The external inspection was conducted by two CH2M HILL outfall specialists and experienced divers-David Wilson and Brad Paulson. The inspection dives were performed on October 16th and 17th while the tide elevation at the outfall site ranged between+7.0 and +8.0 feet above MLLW. Inspection dives were conducted from a 21-foot Munson boat operated by David Orders. Mary Heather Ames (City of Port Townsend Project Manager) was onboard and assisted throughout the inspection process. The only references available for locating the outfall diffuser were the outfall design drawings (not as-builts) from 1966,and therefore other methods were needed to locate the outfall diffuser. Prior to the inspection,temporary onshore markers were installed on the beach directly over the outfall pipe alignment to assist offshore navigation. The shoreline manhole was located and GPS coordinates were recorded to assist the survey vessel to locate the outfall terminus using the distance from the shoreline manhole. The location of the shoreline manhole and diffuser terminus were determined in the field and recorded using a Garmin GPS unit and they are listed below: Shoreline Manhole-- Lat. 48 deg. 08' 32.4" North; Long. 122 deg. 46' 55.0" West Outfall Diffuser Terminus-- Lat. 48 deg. 08'41.6" North; Long. 122 deg. 46' 56.4" West Based on these GPS readings the distance between the shoreline manhole and outfall diffuser terminus is 900 feet (+/-15 feet),and this is a close match to the outfall drawings. 3 Resolution 19-086 Exhibit A Page 46 of 537 PORT TOWNSEND WWTP OUTFALL AND DIFFUSER During the offshore inspection,a tracer dye (Rhodamine WT) was injected into the effluent flow entering the outfall pipe at the Port Townsend WWTP. The dye injection rate (-20 ml/min) and concentration was sufficient to provide a visual reference for potential outfall pipeline leaks. The dye was also detectable to very low concentrations (<1 ppb) using a submersible fluorometer (Self-contained Underwater Fluorometry Apparatus or SCUFA) that CH2M HILL's divers carried along the seabed during the inspection dives. To allow the diver to survey the seabed over the buried outfall pipe,a weighted and sinking bottom-line was layed down along the outfall alignment. This weighted bottom line was started at the offshore diffuser and deployed along the alignment from the survey vessel. Outfall Diffuser Inspection On October 16�h the outfall diffuser was located approximately 910 feet offshore of the shoreline manhole directly in line with the shoreline markers. A visible surface dye patch was observed in the immediate area of the diffuser location. The vessel fathometer indicated water depth at the diffuser was 28-29 feet at 1400 hours (tide level at+7.0 feet above MLLW). Divers descended the marker buoy line to the seabed and located the outfall diffuser. Diver visibility during the dive ranged from 30 to 50 feet. The divers inspected the outfall diffuser starting at the terminal flange (with port),then along the west side of the diffuser to the point of pipe burial (approx. 5 feet inshore of second diffuser joint),and then back along the east side of the diffuser to the terminal flange. During the inspection of the diffuser the dye injection at the WWTP was suspended due to a blockage in the dye tube and therefore the port plumes are normal(uncolored) in the diffuser inspection video from October 16th (Video file: Port Townsend Video 2-Diffuser.avi). To confirm the functionality of the diffuser ports, dye plumes from the diffuser ports were recorded on October 17th- as shown in the video. The outfall diffuser consisted of two 18-foot long pipe sections with four 6-inch ports (two ports on each side of the diffuser-2 pipe sections),two pipe joints, one terminal flange with one 6-inch port,and two large concrete pipe-fit anchors. Figure 1 (based on the 1966 outfall extension project design drawing) provides an annotated illustration of the diffuser section including the port locations and the observed seabed elevation along the diffuser. All five diffuser ports were fully functional and discharing treated wastewater. The diffuser ports are not located at the outfall pipe springline, as depicted in the design drawing. The inspection showed that the four lateral diffuser ports were located with the port inverts approximately 4 inches above the outfall pipe invert,and the invert on the terminal port on the blind flange was approximately 2-3 inches above the pipe invert. The port configurations along the diffuser pipe sections were also different than the design drawing (refer to Figure 1). Table 2 provides a summary of the outfall diffuser conditions and port configurations in the same sequence as the video inspection record. The seabed at the diffuser site consisted of sands, gravel,cobbles,and some large rocks. There was a large amount of macro-algaes attached to the diffuser pipe and anchor blocks. The attached macro-algaes included kelps and leafy red and brown algaes. Water depth measured by divers at the diffuser terminus was 29 feet at the offshore terminus and 26 feet 4 Resolution 19-086 Exhibit A Page 47 of 537 PORT TOWNSEND WWTP OUTFALL AND DIFFUSER at the inshore end of the diffuser section where it entered the seabed (recorded at +7 foot tide stage). Outfall Corrosion Assessment During the inspection of the outfall diffuser,the inspection divers tapped the pipe,joints and bolts with a hammer to assess integrity. Removal of a bolt from the end-flange of the diffuser or mechanical joint fitting for corrosion analysis was not feasible or prudent given the condition of the exposed Cl pipe. CH2M HILL's corrosion specialist,Jerry Duppong, was consulted regarding the condition assessment and his input is incorporated into this subsection. The outfall diffuser is comprised of relatively thick-walled cast iron(minimum thickness of 18-inch-diameter cast iron pipe used at that time was about 0.5 inches),which was commonly used in the 1960s-before the development of ductile iron. An extensive corrosion layer covers the entire extent of the diffuser section. The exposed joints and bolts were completely"fused" within a thick corrosion layer and the fasteners were almost indistinguishable within the corrosion deposits. Much of the diffuser section is also covered in thick biological growth as well. While the diffuser section remains in tact, it's not clear the extent to which"graphitization' of the pipe surface has occurred. Graphitization is the process under which iron is leached from the pipe,leaving a structure comprised mostly of carbon. The structure has significantly reduced strength,is brittle,and eventually fails. Graphitization is common in near-shore seawater conditions where the water is rich in oxygen. Because of the abundant current energy at the diffuser location oxygen levels are likely relatively high. In warmer, shallower conditions severe graphitization of cast iron pipe has been found to occur in 20 years or less. It's not possible to assess the precise amount of graphitization without removing a sample of the diffuser for further analysis. The divers did not collect a sample because of concerns with damaging the diffuser. Due to the corroded nature of the pipe,a fastener or piece of the diffuser would probably have to be torch cut for removal. While subsequent collection and collection of a section of the diffuser would aid in assessing the remaining useful life of the diffuser to a greater level of detail,we don't believe that is necessary to assist in development of a strategy for moving forward in pursuit of an approach that addresses the detioriating condition of the existing outfall. Outfall Alignment Survey— Offshore to Shoreline On October 17th,the outfall pipeline alignment was inspected for leak, discontinuities and seabed plant/algae cover. The outfall diffuser was located and marked and a weighted dive transect line was deployed and anchored along the outfall alignment from the inshore end of the diffuser section to within 100 feet of the waters edge (total distance of 750 feet). The dye injection was active at the WWTP and a distinct surfacing plume was observed in the area of the diffuser. Divers descended the marker buoy line to the seabed and located the start of the transect line inshore of the outfall diffuser. Diver visibility during the inspection dive ranged from 30 to 40 feet. The divers inspected the outfall alignment route and either side of the 5 Resolution 19-086 Exhibit A Page 48 of 537 PORT TOWNSEND WWTP OUTFALL AND DIFFUSER alignment(within visual range). The divers video taped the seabed conditions along the alignment and used the SCUFA instrument to detect and record the presence of dye leaking from the outfall. The time increments and location along the outfall alignment were kept by the divers and then compared with the SCUFA time record to assess possible leak locations. The video record of the conditions on the outfall alignment on October 17th is in video file Port Townsend Video 3-Outfall Alignment.avi in Attachment B. Figure 2 provides a summary of the conditions observed along the outfall alignment from the diffuser to the shoreline. The seabed immediately inshore of the exposed diffuser (where the outfall emerges from burial-Station 0) consisted of sands, gravels,and some large rocks. The"stationining" used for this discussion begins at the outfall diffuser and increases toward shore. It is intended simply to track the location of the diver observations for this discussion and does not correlate to the stationing presented in Figure 2. The depth at Station 0 was 25 feet. There were some leafy macro-algaes attached to rocks and some kelp,but there were also scattered patches of surf grass for a distance of 50-75 feet along the alignment from the pipe burial(start of transect). The seabed at Station 75 to 350 along the outfall alignment was densely covered with attached macro-algaes including kelps and leafy red and brown algaes. No dye leaks from the buried outfall or seabed discontinuities (e.g. scour depressions)were visible along the transect line. Beginning near Station 350 and continuing to approximately Station 450 feet the seabed along the outfall alignment was covered with dense stands of surf grass that reached 4 to 5 feet in height. No dye leaks from the buried outfall or seabed discontinuities were visible along the transect line. Near Station 400 a small concrete block was observed sitting on the seabed and this may have served as an anchor for work vessels in the past that were constructing the original outfall or extending the outfall. No pipe or joints were observed above the seabed. From Station 450 to Station 700 the seabed along the outfall alignment was sands with patches of surf grass and eelgrass. No dye leaks from the buried outfall or seabed discontinuities were visible along the transect line. At Station 700 the seabed changed to simply sands (water depth-12 feet) and continued as sands to the waters edge at Station 800. The divers observed small visible leaks of dye along the outfall alignment at roughly 35 feet from the shoreline. Following completion of the dive inspection the SCUFA instrument data were downloaded and analyzed. Figure 3 provides a time line plot of the dye measurements recorded along the outfall alignment. This plot clearly identifies the presence of numerous nearshore leaks from the buried outfall pipeline. The only leaks that were visible to the divers were two sites-one located at 35 feet from the waters edge and the second at 5 feet from the waters edge. These instrument data indicate that additional leaks were present between the two observed leaks as well as some additional leakage offshore approximately 200 to 300 feet. All of these outfall leaks were located in the older, original outfall pipeline section. 6 Resolution 19-086 Exhibit A Page 49 of 537 PORT TOWNSEND WWTP OUTFALL AND DIFFUSER Summary of Findings The condition assessment is summarized as follows: • Numerous small outfall pipeline leaks were detected in the nearshore region between the shoreline and 300 feet offshore,however the outfall pipeline is functioning to convey most effluent flows to the offshore diffuser; • The outfall diffuser pipe,joints,and terminal flange were intact and without leaks, and all five outfall diffuser ports were intact,open,and fully functional; • The anchor blocks securing the diffuser section were intact and the interior of the diffuser section appeared to be clear of debris; • Pipe corrosion on the exposed outfall diffuser section and joints was extensive,evenly distributed,and what would be expected for a section of cast iron setting in seawater for 40 years or more; • The interior outfall pipeline invert contains substantial amount of gravels and rocks (small to large) and substantial growths (possible bacteria mats) that reduces the pipe volume by 5 to 15% along the pipe-essentially a continuous layer is present in the pipe from 117 feet offshore to 862 feet offshore (end of inspection); • Rock accumulation in the outfall invert at 862 feet could exceed 25% and this blockage did not allow for internal inspection of the diffuser section; • Outfall joint offsets and discontinuities were noted at numerous locations,but no clear joint failures were observed. Recommendations We recommend the City pursue development of alternatives for replacement of the existing WWTP outfall. The condition of the outfall system does not warrant pursuit of a"leave it as-is" or a"do nothing" approach. Some level of replacement will be needed soon. Whether such a replacement is for the entire system or only a portion will be evaluated in Task 2 of this project. Although it was mostly functional at the time of our inspection,it is clear the outfall system is nearing its useful life expectancy. The three key factors supporting our recommendation are: 1. The historic and on-going leakage of the older,near-shore section,which should reasonably be expected to continue and get worse over time 2. The substantial corrosion of the exposed cast iron outfall diffuser over its 40+years exposed to seawater. While it is remains intact and functional,it is likely undergoing active graphitization,and may not have too many years before it collapses. 3. The gravel debris in the outfall pipeline at the downstream end. This debris reduces the capacity of the outfall,which may not be an issue now,but could be an issue in the near- term future as the City expands. Removing this gravel material is possible but could result in damage to the outfall pipeline and the end diffuser. 7 Resolution 19-086 Exhibit A Page 50 of 537 PORT TOWNSEND WWTP OUTFALL AND DIFFUSER In addition to the condition of the existing outfall system warranting a pro-active approach, the apparent high-quality habitat through which the outfall traverses elevates the importance of a timely deliberate pursuit of a replacement strategy. As indicated above, and in work done by others to assess the extent of eelgrass growth in this location,the area in which the existing outfall is located is covered to a large degree in high-quality eelgrass. The presence of eelgrass will increase the regulatory scrutiny of any replacement alternatives that include disturbance of the seabed. 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a a ? a a i \ i > ? > / > > > 0 D 0 0 ° \ 2 \ ° \ 0 & t & \ b \ \ d f \ \ U) \ \ / / / / � 5 s s � s s c % / $ $ / $ $ / $ / / / / @ I e 2 2 0 2 2 _c 2 e @ 3 k ° \ $ � 7 / \ ƒ $ ƒ R @ -j / # # / @ @ / \ / / ƒ # # @ c E e w Resolution 19-086 Ex6a»a Page S of 5 z ° > U) _ \ U) E 2 0 % / �/ R o 7 \ 5 \ / o \ 7 \ 0 § / § $ k k _ _r_ _ _ a) @ a E E ƒ § $ § $ k c k // / E \ E E 2 g 0 _0 2 k , c ® % a = o \ ƒ \ \ \ § I q \ / > e @ o § m 0 m \ °ƒ 0 / f / c E E c 2 ± 2 2 0 \ 0 / ) k / k 7 \ \ \ 2 - - o 2 § o b o o / - U) _ ƒ m / \ CO 3 m CO 'a. 2 a) @ k / k 0 \ 2 F _ 2 a G G / o \ / U U) 7 2 a o $ / / / / § � \ g § / \/ \o E \ 0- \ 7 a ) e o 3 \ 7 \ / \ . . a \ ; 2 ƒ 3 3 % ƒ % ƒ \ 0 = _ 2 \ f \ \ ? ? » » 5 0 0 c@ § _� k k E t E t o % o o 0 k § 2 E E / / £ \ £ \ 0 a \ t 2 2 \ g \ E t 0 0 0 § \ e e ® n .R � ._ / $ 3 E 0 7 .R / / ® ® 7 3 7 ) � / / I a. f I E \ \ f f u) E u) E \ a 0 \ k \ \ 0 0 \ £ \ £ o 0 0 ® c c § \ f \ / / f f \ 2 0 0 > / 0 -0 \ \/ / 2 2 2 2 CL P o & E E o 0 0 § o m E t 0 § / g ) 2 2- C o c 0- a R 2 \ £ '0 n = \ ° n U g em \ u o \ 5 > § / / \ 2 \ 0 f = \ ■ % E E . 0 0 7 / \ \ k ) / \ % f / EL f f f f o o ° ° i = CL U) r e r & & f f / ) .a .a & ? \ \ \ \ / / \ \ C c- ƒ / t t t t t t o \ \ \ \ \ P 0 0 0 / / / / / / c ƒ $ ƒ ƒ 7 § 2 ƒ c ƒ ƒ ƒ ƒ ƒ ƒ o c c k ° \ \ © $ $ $ (0 b � @ - w / w 7 c c c ƒ c / / / w c c Resolution 19-086 Exhibit A Page 55 of 537 Table 2 Summary of Outfall Diffuser Conditions Observations Diffuser Feature Depth Description and Condition Measured Terminal Flange to 29 feet at port Terminal flange is heavily corroded.Terminal flange is bolted to the end of the Diffuser Pipe and centerline last pipe section and the connection completely fused with corrosion.Terminal Terminal Port(#1) port(6-inch)is located at the base of the flange-port invert is-2-3 inches above the invert of the 18-inch pipe. Port was clear and interior of diffuser pipe at terminus is clear with no obstructions or deposits. Port discharge was intermittent with velocities from zero to-0.5 fps. Outfall pipe is supported by the anchor block and pipe invert was approx. 18- inches above the seabed.Terminal flange is only 4-5 inches beyond the anchor block. West-side Diffuser Port 28 feet at port 6-inch port located 4.5 ft inshore of terminal flange and-18 inches from offshore (#2) CL anchor block. Port(6-inch)is located with invert-4 inches above the invert of the 18-inch pipe. Port was clear and interior of diffuser was clear with no obstructions or deposits. Port discharge was continuous with estimated velocities from 0.2 to -0.5 fps. Outfall pipe pipe invert was approx. 12-inches above the seabed. Diffuser Joint#1 28 feet Pipe joint intact with no leaks. Joint is fused due to corrosion and heavily encrusted with marine growths. Entire pipe and joint is above seabed(supported by concrete anchor blocks),with approximately 9-12 inches of space under the outfall joint. West-side Diffuser Port 28 feet at port 6-inch port located 13.5 ft inshore of Diffuser Joint#1 and 4.5 ft offshore of (#5) CL Diffuser Joint#2. Port(6-inch)is located with invert-4 inches above the invert of the 18-inch pipe. Port opening was slightly blocked by a large rock buried in seabed. Diffuser port invert was approx. 1-2 inches below the adjacent seabed but scoured out in front of port(except rock). Port was clear and functioning,and interior of diffuser pipe was clear with no obstructions or deposits. Port discharge was continuous with velocities from 0.2 to-0.5 fps. Diffuser Joint#2 27 feet Pipe joint intact with no leaks. Joint is fused due to corrosion and heavily encrusted with marine growths. Pipe mostly buried in seabed and only 12-14 inches of top of joint is visible(80%buried into seabed). Eastside Diffuser Port 28 feet at port 6-inch port located 13.5 ft offshore of Diffuser Joint#2 and 4.5 ft inshore of (#4) CL Diffuser Joint#1. Concrete anchor block located 18 inches offshore of port. Port (6-inch)is located with invert-4 inches above the invert of the 18-inch pipe. Diffuser port invert was approx.9 inches above the adjacent seabed,and the pipe invert is partially scoured out along eastside. Port was clear and functioning, and interior of diffuser pipe was clear with no obstructions or deposits. Port discharge was continuous with velocities from 0.2 to-0.5 fps. Eastside Diffuser Port 28 feet at port 6-inch port located 4.5 ft offshore of Diffuser Joint#1 and 13.5 ft inshore of (#3) CL terminal flange. Port(6-inch)is located with invert-4 inches above the invert of the 18-inch pipe. Diffuser port invert was approx. 12 inches above the adjacent seabed,and the pipe invert is scoured under pipe. Port was clear and functioning,and interior of diffuser pipe was clear with no obstructions or deposits. Port discharge was continuous with velocities from 0.2 to-0.5 fps. Resolution 19-086 Exhibit A Page 56 of 537 Resolution 19-086 Exhibit A Page 57 of 537 V. 1 Esc- r , 'jCA ILE West Side Port. (#5) West Side Port. (#2) Port slightly blocked on Port open and 6' to 8" invert by embedded rock. above seabed. 70,,0 63,c OY1T1eWZ,L r 91 W7, ON �.QT Joint intact and fused Joint intact and fused �",,with corrosion with corrosion ' _ / _ �.. Flange fused to pipe and intact ,,,ff; `- '� ,��'��•j 6" end port open (#1) . Observed seabed (sands and gravel) East Side Port. (#3) i 7'5` �`0,'9T Slight port occlusion East Side Port. #4 ( ) due to large barnacles NOTE: F[F-.r LIT 101FC v c [„yL. �'` Open and clear. on inshore side. Base drawing if from 1966 design drawings C�lFFrJSER SEC 7101V 01'v1 Y. of Port Townsend WWTP Outfall Extension. IVOTZ.' , 4DIF1=U5,Fe WILL Be MOUNT,5D X47 5LI61-17 i��`�'Wa�,yIlk . O�w�,,��r.' �,'f/"67 I,I 6L5, CO/V"E C T TQ Dt_ ,�, e4 Q - r;� �.,,� 0 UTI L I Z/I-1v A-10,eM,4G --1011V7 DEf'L EC T!0! 'ppb, ts:. CRT T WN ND SEWAGE SYSTEM IMVRCVEMENT PROGRAM DRAWING r;: 6C� CCUN T f .. w g SHINE TON UTF - - �- TFNSION FIGURE 1 �.� � F� L� .`l�F ay � r t��1 ' Field Observations of Diffuser WB112007003SEA C H 2M H I LL Resolution 19-086 Exhibit A Page 58 of 537 Resolution 19-086 Exhibit A Page 59 of 537 iJ U LJ _TJ 0 E�] U EG = Eel grass G1 SG = Surf grass p � K = Kelp o ❑ � � K K K K Diffuser 18"' Outfall K K K K K K SG K section SG SG K K (36 feet) EG EG EG SG G SG K K K K Y EG REGEG t� Point of Discharge EXISTING M \ +1 EXISTING AT BEACH �• M" E-' 3 small � LD leaks EXISTING WWfF Connection point 3 small (original outfall to leaks 03 extended outfall - 1966) - PLAN no structure above grade) 30 30 City of Port Townsend 20 Datum 0.00 =4.93 MSL 20 10 10 Extreme._Higher High Water, EI. 7.± EXISTING o Mean Higher High Water, EI. 3.47 0 RMH IM E� ,4.s RIM E� ,z.z E?tf�EIEACH"(M Mean Sea Level NGVD Ei. 0.00 CH 0 IE 5,5 1 R]M EL 12.2 1�'� Outfall IMAT Mean Lower Low Water El. -4.93 RIM EL 18.2 IL 2.8 -10 Approx. 36-foot diffuser -10 above grade. -20 IE -11 '3 • Ports functioning -2p 3 pipe leaks shallow (Not visib e • Anchor blocks (2) intact nearshore region during -3p Concrete block _30 inspection) EFFLUENT 25+00 below grade DIEFusER 3 Small leaks at ]E -28.8 -40 200-300' offshore -40 a End of internal inspection a•:rt* a -50 (partial blockage) -50 0+00 5+00 10+00 15+00 20+00 PROFILE 1"-200'HORIZ 1"-40' VERT FIGURE 2 Field Observations of Outfall WB112007003SEA C H 2M H I LL Resolution 19-086 Exhibit A Page 61 of 537 c � CD y m r c O9?� J cn L �. 0-0 L ?� O. 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