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HomeMy WebLinkAbout2019.07.11 Operations & Maintenance Manual for the Rainier Street Regional Stormwater Pond Civil Engineers ● Structural Engineers ● Landscape Architects ● Community Planners ● Land Surveyors Operations and Maintenance Manual PREPARED FOR: City of Port Townsend 250 Madison Street Port Townsend, WA 98368 PROJECT: Rainier Street Regional Stormwater Facility Tax Parcel 001162017 Jefferson County, WA 2160137.10 PREPARED BY: Dan Osier, PE Senior Engineer REVIEWED BY: Doreen S. Gavin, PE, LEED AP BD+C President DATE: July 2019 Operations and Maintenance Manual PREPARED FOR: City of Port Townsend 250 Madison Street Port Townsend, WA 98368 PROJECT: Rainier Street Regional Stormwater Facility Tax Parcel 001162017 Jefferson County, WA 2160137.10 PREPARED BY: Dan Osier, PE Senior Engineer REVIEWED BY: Doreen S. Gavin, PE, LEED AP BD+C President DATE: July 2019 I hereby state that this Operations and Maintenance Manual for the Rainier Street Regional Facility project has been prepared by me or under my supervision, and meets the standard of care and expertise that is usual and customary in this community for professional engineers. I understand that Jefferson County does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities prepared by me. Operations and Maintenance Manual Rainier Street Regional Stormwater Facility 2160137.10 Table of Contents Section Page 1.0 Proposed Project Description ...................................................................................................... 1 2.0 Maintenance Importance and Intent ............................................................................................. 1 3.0 Responsible Parties ....................................................................................................................... 1 4.0 Facilities Requiring Maintenance ................................................................................................. 2 5.0 Maintenance Instructions .............................................................................................................. 2 6.0 Vegetation Maintenance ................................................................................................................ 2 7.0 Pollution Source Control Measures ............................................................................................. 2 8.0 Annual Cost of Maintenance ......................................................................................................... 2 9.0 Conclusion ...................................................................................................................................... 2 Exhibits Exhibit A Project Map Exhibit B Maintenance Instructions Operations and Maintenance Manual Rainier Street Regional Stormwater Facility 1 2160137.10 1.0 Proposed Project Description This report accompanies the civil engineering plans and documents for the proposed Rainier Street Regional Stormwater Facility, which is proposed to provide stormwater flow control for commercial properties along the developing Rainier Street, formerly Howard Street, corridor in Port Townsend, Washington. The facility is to be located in Parcel No. 001162017 (the “pond parcel”) in Jefferson County. The pond parcel is a portion of the Northeast Quarter of the Northwest Quarter of Section 16, Township 30 North, Range 1 West of the Willamette Meridian. In connection with the previous Howard Street corridor design, a combination wet/detention pond was constructed in the eastern portion of Parcel No. 001094006, which was sized to accommodate stormwater runoff from improvements in Rainier Street, a portion of West Sims Way, and Parcel No. 001094002. The proposed facility is located approximately one-quarter mile to the west of the existing pond and will function in combination with it to serve these areas, as well as the Rainier Street, formerly Howard Street, commercial properties, and future development of Parcel No. 001094006. A stormwater conveyance system will traverse Parcel No. 001094006, along with a 10-foot wide pedestrian path. The path will cross the pond parcel and connect to Mill Road. Access to the proposed stormwater facility will be from Mill Road. Stormwater management will comply with the Washington State Department of Ecology 2012 Stormwater Management Manual for Western Washington (SWMMWW), as adopted by Jefferson 2.0 Maintenance Importance and Intent The importance of maintenance for the proper functioning of stormwater control facilities cannot be over emphasized. A substantial portion of failures (clogging of filters, resuspension of sediments, loss of storage capacity, etc.) are due to inadequate maintenance. Stormwater Best Management Practice (BMP) maintenance is essential to ensure that BMPs function as intended throughout their full life cycle. The fundamental goals of maintenance activities are to insure the entire flow regime and treatment train designed for this site continue to fully function. For this site, these include:  Maintain ability to safely convey design stormwater flows.  Maintain ability to treat stormwater runoff quality.  Preserve soil and plant health, as well as stormwater flow contact with plant and soil systems.  Clearly identify systems so they can be protected.  Keep maintenance costs low.  Prevent large-scale or expensive stormwater system failures.  Prevent water quality violations or damage to downstream properties. The intent of this section and manual is to pass on to the responsible party(ies) all the information critical to understand the design of the system, risks and considerations for proper use, suggestions for maintenance frequencies, and cost so that realistic budgets can be established. 3.0 Responsible Parties City of Port Townsend will be responsible for maintaining all stormwater facilities. It is recommended that the owner periodically hire a professional who is knowledgeable in the proper maintenance and operations of stormwater facilities to inspect them. Operations and Maintenance Manual Rainier Street Regional Stormwater Facility 2 2160137.10 4.0 Facilities Requiring Maintenance The project site has several privately owned facilities that the owner will need to maintain. These facilities include control structures, catch basins, modular wetlands, and bioretention. 5.0 Maintenance Instructions The parties responsible for maintenance must review and apply the maintenance requirements contained herein. These maintenance instructions outline conditions for determining if maintenance actions are required, as identified through inspection. However, they are not intended to be measures of the facility's required condition at all times between inspections. Exceedance of these conditions at any time between inspections or maintenance activity does not automatically constitute a violation of these standards. However, based on inspection observations, the inspection and maintenance presented in the checklists shall be adjusted to minimize the length of time that a facility is in a condition that requires a maintenance action. A log of maintenance activity that indicates what actions were taken must be kept onsite and be available for inspection by the County. Each facility on this project site has different maintenance requirements. These requirements are summarized in Exhibit B. 6.0 Vegetation Maintenance None of the stormwater facilities on this project depend on vegetation for proper functioning. However, it is necessary to trim vegetation so that it does not clog or otherwise interfere with operation of stormwater systems. More detailed instructions are provided in Exhibit B. 7.0 Pollution Source Control Measures The property owner should take measures to ensure that pollutants do not enter the drainage system. For this site, these tasks include picking up litter and trash and ensuring dumpsters are emptied frequently enough to avoid overloads and spills. The owner should also periodically check the site to ensure that pollutants, such as vehicle fluids, are not being dumped into drains. 8.0 Annual Cost of Maintenance Maintenance of these facilities will likely require a professional contractor to visit and inspect the site twice a year and make minor fixes as needed. These visits will likely cost $300 per year. Most likely, there will be some more expensive repairs required every ten years that will cost around $3,000. As a result, we recommend the owner budget $600 per year for both routine and major maintenance work. This does not include the cost of trash collection or general housekeeping. 9.0 Conclusion Proper maintenance is important to the proper functioning of the stormwater facilities on this site. Following these guidelines will ensure that the site continues to function as intended and will help avoid expensive repairs in the future. Operations and Maintenance Manual Rainier Street Regional Stormwater Facility 3 2160137.10 This analysis is based on data and records either supplied to or obtained by AHBL. These documents are referenced within the text of the analysis. The analysis has been prepared using procedures and practices within the standard accepted practices of the industry. AHBL, Inc. Dan Osier, PE Senior Engineer KSS/ July 2019 Q:\2016\2160137\10_CIV\NON_CAD\REPORTS\O&M\20190711 Rpt (O&M) 2160137.10.docx Operations and Maintenance Manual Rainier Street Regional Stormwater Facility 2160137.10 Exhibit A Project Map M I L L R O A D 001-093-020 001-094-006 001-162-017 001-161-002 001-093-012 DAVIS SMITH PACIFIC FUNDING PORT TOWNSEND PAPER CORP. CITY OF PORT TOWNSEND LARRY SCOTT MEMORIAL TRAIL 001-161-004 SF SF CL SL 1 1 2 2 LEGEND RIGHT-OF-WAY  PROPERTY LINE CLEARING  PRO-ECT LIMITS REMOVE E;ISTING ASPHALT FILTER FA%RIC FENCE INLET PROTECTION INTERCEPTOR SWALE SAWCUT LINE E;ISTING MINOR CONTOUR E;ISTING MA-OR CONTOUR KEYNOTES E;ISTING UTILITY POLE TO %E RELOCATED %Y OTHERS CONTRACTOR TO PRESERVE AND PROTECT E;ISTING UTILITES 1 2 CL SF IP SL 2 C1.10 1 C1.10 N HORI=ONTAL SCALE 0 60 120 1 60 FEET 30 221 NRUWK 30WK SWUHHW SXLWH 300 TDFRPD WA 9403 23.33.2422TEL ZZZ.DKEO.FRPWE% TACOMA SEATTLE SPO.ANE TRI-CITIES Know what's below. before you dig.Call R 23.33.272 FA; PORT TOWNSEND REGIONAL STORMWATER FACILITY CITY OF PORT TOWNSEND 20 MADISON STREET PORT TOWNSEND WA 936 WOR. ORDER  02 2160137 071619 PERMIT SET DO S.DG 12 PORT TOWNSEND REGIONAL STORMWATER FACILITY SECTIONS 9 & 16, TOWNSHIP 30N, RANGE 1W, W.M., JEFFERSON COUNTY, WA DATE -XO\ 1 2019 FILENAME 4?2016?2160137?10BCIV?CAD?2160137-SH-TESC-DEMO.GZJ C1.00 TESC AND DEMOLITION PLAN 2 Operations and Maintenance Manual Rainier Street Regional Stormwater Facility 2160137.10 Exhibit B Maintenance Instructions Volume V – Runoff Treatment BMPs – December 2014 4-32 4.6 Maintenance Standards for Drainage Facilities The facility-specific maintenance standards contained in this section are intended to be conditions for determining if maintenance actions are required as identified through inspection. They are not intended to be measures of the facility's required condition at all times between inspections. In other words, exceedence of these conditions at any time between inspections and/or maintenance does not automatically constitute a violation of these standards. However, based upon inspection observations, the inspection and maintenance schedules shall be adjusted to minimize the length of time that a facility is in a condition that requires a maintenance action. Table 4.5.2 Maintenance Standards No. 1 – Detention Ponds Maintenance Component Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed General Trash & Debris Any trash and debris which exceed 1 cubic feet per 1,000 square feet. In general, there should be no visual evidence of dumping. If less than threshold all trash and debris will be removed as part of next scheduled maintenance. Trash and debris cleared from site. Poisonous Vegetation and noxious weeds Any poisonous or nuisance vegetation which may constitute a hazard to maintenance personnel or the public. Any evidence of noxious weeds as defined by State or local regulations. (Apply requirements of adopted IPM policies for the use of herbicides). No danger of poisonous vegetation where maintenance personnel or the public might normally be. (Coordinate with local health department) Complete eradication of noxious weeds may not be possible. Compliance with State or local eradication policies required Contaminants and Pollution Any evidence of oil, gasoline, contaminants or other pollutants (Coordinate removal/cleanup with local water quality response agency). No contaminants or pollutants present. Rodent Holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents destroyed and dam or berm repaired. (Coordinate with local health department; coordinate with Ecology Dam Safety Office if pond exceeds 10 acre-feet.) Volume V – Runoff Treatment BMPs – December 2014 4-33 No. 1 – Detention Ponds Maintenance Component Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Beaver Dams Dam results in change or function of the facility. Facility is returned to design function. (Coordinate trapping of beavers and removal of dams with appropriate permitting agencies) Insects When insects such as wasps and hornets interfere with maintenance activities. Insects destroyed or removed from site. Apply insecticides in compliance with adopted IPM policies Tree Growth and Hazard Trees Tree growth does not allow maintenance access or interferes with maintenance activity (i.e., slope mowing, silt removal, vactoring, or equipment movements). If trees are not interfering with access or maintenance, do not remove If dead, diseased, or dying trees are identified (Use a certified Arborist to determine health of tree or removal requirements) Trees do not hinder maintenance activities. Harvested trees should be recycled into mulch or other beneficial uses (e.g., alders for firewood). Remove hazard Trees Side Slopes of Pond Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted berm embankment. Slopes should be stabilized using appropriate erosion control measure(s); e.g., rock reinforcement, planting of grass, compaction. If erosion is occurring on compacted berms a licensed civil engineer should be consulted to resolve source of erosion. Storage Area Sediment Accumulated sediment that exceeds 10% of the designed pond depth unless otherwise specified or affects inletting or outletting condition of the facility. Sediment cleaned out to designed pond shape and depth; pond reseeded if necessary to control erosion. Liner (If Applicable) Liner is visible and has more than three 1/4-inch holes in it. Liner repaired or replaced. Liner is fully covered. Pond Berms (Dikes) Settlements Any part of berm which has settled 4 inches lower than the design elevation. If settlement is apparent, measure berm to determine amount of settlement. Settling can be an indication of more severe problems with the berm or outlet works. A licensed civil engineer should be consulted to determine the source of the settlement. Dike is built back to the design elevation. Piping Discernable water flow through pond berm. Ongoing erosion with potential for erosion to continue. (Recommend a Goethechnical engineer be called in to inspect and evaluate condition and recommend repair of condition. Piping eliminated. Erosion potential resolved. Volume V – Runoff Treatment BMPs – December 2014 4-34 No. 1 – Detention Ponds Maintenance Component Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Emergency Overflow/ Spillway and Berms over 4 feet in height. Tree Growth Tree growth on emergency spillways creates blockage problems and may cause failure of the berm due to uncontrolled overtopping. Tree growth on berms over 4 feet in height may lead to piping through the berm which could lead to failure of the berm. Trees should be removed. If root system is small (base less than 4 inches) the root system may be left in place. Otherwise the roots should be removed and the berm restored. A licensed civil engineer should be consulted for proper berm/spillway restoration. Piping Discernable water flow through pond berm. Ongoing erosion with potential for erosion to continue. (Recommend a Goethechnical engineer be called in to inspect and evaluate condition and recommend repair of condition. Piping eliminated. Erosion potential resolved. Emergency Overflow/ Spillway Emergency Overflow/ Spillway Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. (Rip-rap on inside slopes need not be replaced.) Rocks and pad depth are restored to design standards. Erosion See “Side Slopes of Pond” Volume V – Runoff Treatment BMPs – December 2014 4-37 No. 4 – Control Structure/Flow Restrictor Maintenance Component Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed General Trash and Debris (Includes Sediment) Material exceeds 25% of sump depth or 1 foot below orifice plate. Control structure orifice is not blocked. All trash and debris removed. Structural Damage Structure is not securely attached to manhole wall. Structure securely attached to wall and outlet pipe. Structure is not in upright position (allow up to 10% from plumb). Structure in correct position. Connections to outlet pipe are not watertight and show signs of rust. Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. Any holes--other than designed holes--in the structure. Structure has no holes other than designed holes. Cleanout Gate Damaged or Missing Cleanout gate is not watertight or is missing. Gate is watertight and works as designed. Gate cannot be moved up and down by one maintenance person. Gate moves up and down easily and is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Gate is rusted over 50% of its surface area. Gate is repaired or replaced to meet design standards. Orifice Plate Damaged or Missing Control device is not working properly due to missing, out of place, or bent orifice plate. Plate is in place and works as designed. Obstructions Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having the potential of blocking) the overflow pipe. Pipe is free of all obstructions and works as designed. Manhole See “Closed Detention Systems” (No. 3). See “Closed Detention Systems” (No. 3). See “Closed Detention Systems” (No. 3). Catch Basin See “Catch Basins” (No. 5). See “Catch Basins” (No. 5). See “Catch Basins” (No. 5). Volume V – Runoff Treatment BMPs – December 2014 4-38 No. 5 – Catch Basins Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is performed General Trash & Debris Trash or debris which is located immediately in front of the catch basin opening or is blocking inletting capacity of the basin by more than 10%. No Trash or debris located immediately in front of catch basin or on grate opening. Trash or debris (in the basin) that exceeds 60 percent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of six inches clearance from the debris surface to the invert of the lowest pipe. No trash or debris in the catch basin. Trash or debris in any inlet or outlet pipe blocking more than 1/3 of its height. Inlet and outlet pipes free of trash or debris. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within the catch basin. Sediment Sediment (in the basin) that exceeds 60 percent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of 6 inches clearance from the sediment surface to the invert of the lowest pipe. No sediment in the catch basin Structure Damage to Frame and/or Top Slab Top slab has holes larger than 2 square inches or cracks wider than 1/4 inch (Intent is to make sure no material is running into basin). Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than 3/4 inch of the frame from the top slab. Frame not securely attached Frame is sitting flush on the riser rings or top slab and firmly attached. Fractures or Cracks in Basin Walls/ Bottom Maintenance person judges that structure is unsound. Basin replaced or repaired to design standards. Grout fillet has separated or cracked wider than 1/2 inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. Pipe is regrouted and secure at basin wall. Settlement/ Misalignment If failure of basin has created a safety, function, or design problem. Basin replaced or repaired to design standards. Vegetation Vegetation growing across and blocking more than 10% of the basin opening. No vegetation blocking opening to basin. Vegetation growing in inlet/outlet pipe joints that is more than six inches tall and less than six inches apart. No vegetation or root growth present. Contamination and Pollution See "Detention Ponds" (No. 1). No pollution present. Volume V – Runoff Treatment BMPs – December 2014 4-39 No. 5 – Catch Basins Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is performed Catch Basin Cover Cover Not in Place Cover is missing or only partially in place. Any open catch basin requires maintenance. Catch basin cover is closed Locking Mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts into frame have less than 1/2 inch of thread. Mechanism opens with proper tools. Cover Difficult to Remove One maintenance person cannot remove lid after applying normal lifting pressure. (Intent is keep cover from sealing off access to maintenance.) Cover can be removed by one maintenance person. Ladder Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, not securely attached to basin wall, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. Metal Grates (If Applicable) Grate opening Unsafe Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and Debris Trash and debris that is blocking more than 20% of grate surface inletting capacity. Grate free of trash and debris. Damaged or Missing. Grate missing or broken member(s) of the grate. Grate is in place and meets design standards. No. 6 – Debris Barriers (e.g., Trash Racks) Maintenance Components Defect Condition When Maintenance is Needed Results Expected When Maintenance is Performed General Trash and Debris Trash or debris that is plugging more than 20% of the openings in the barrier. Barrier cleared to design flow capacity. Metal Damaged/ Missing Bars. Bars are bent out of shape more than 3 inches. Bars in place with no bends more than 3/4 inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars are loose and rust is causing 50% deterioration to any part of barrier. Barrier replaced or repaired to design standards. Inlet/Outlet Pipe Debris barrier missing or not attached to pipe Barrier firmly attached to pipe Volume V – Runoff Treatment BMPs – December 2014 4-40 No. 7 – Energy Dissipaters Maintenance Components Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed External: Rock Pad Missing or Moved Rock Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil. Rock pad replaced to design standards. Erosion Soil erosion in or adjacent to rock pad. Rock pad replaced to design standards. Dispersion Trench Pipe Plugged with Sediment Accumulated sediment that exceeds 20% of the design depth. Pipe cleaned/flushed so that it matches design. Not Discharging Water Properly Visual evidence of water discharging at concentrated points along trench (normal condition is a “sheet flow” of water along trench). Intent is to prevent erosion damage. Trench redesigned or rebuilt to standards. Perforations Plugged. Over 1/2 of perforations in pipe are plugged with debris and sediment. Perforated pipe cleaned or replaced. Water Flows Out Top of “Distributor” Catch Basin. Maintenance person observes or receives credible report of water flowing out during any storm less than the design storm or its causing or appears likely to cause damage. Facility rebuilt or redesigned to standards. Receiving Area Over-Saturated Water in receiving area is causing or has potential of causing landslide problems. No danger of landslides. Internal: Manhole/Chamber Worn or Damaged Post, Baffles, Side of Chamber Structure dissipating flow deteriorates to 1/2 of original size or any concentrated worn spot exceeding one square foot which would make structure unsound. Structure replaced to design standards. Other Defects See “Catch Basins” (No. 5). See “Catch Basins” (No. 5). Volume V – Runoff Treatment BMPs – December 2014 4-51 No. 18 – Catchbasin Inserts Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Performed General Sediment Accumulation When sediment forms a cap over the insert media of the insert and/or unit. No sediment cap on the insert media and its unit. Trash and Debris Accumulation Trash and debris accumulates on insert unit creating a blockage/restriction. Trash and debris removed from insert unit. Runoff freely flows into catch basin. Media Insert Not Removing Oil Effluent water from media insert has a visible sheen. Effluent water from media insert is free of oils and has no visible sheen. Media Insert Water Saturated Catch basin insert is saturated with water and no longer has the capacity to absorb. Remove and replace media insert Media Insert-Oil Saturated Media oil saturated due to petroleum spill that drains into catch basin. Remove and replace media insert. Media Insert Use Beyond Normal Product Life Media has been used beyond the typical average life of media insert product. Remove and replace media at regular intervals, depending on insert product.