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APPROVED STM RESUB2 BLD2023-0174+stormwater DRAINAGE_Plan+2.2.2024_11.30.54_AM+40367691 /195 RESUB Feb 02 2024 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT BLD2023-0174 Category 1 Drainage flan for the New House at 1050 Walnut 5t. Tax # 004342-035-015-00 Application #13LD2023-0174 City of Edmonds Eric Rymer w/ Rymer Homes 4224 211 th Ave 5E Snohomish WA 98290 425-328-5617 ericgrynerhomes.com November 07, 2022 Revised September 14, 2023 Revised January 4, 2024 Job # 22-32262 1 /04/24 Design Build Services, Inc. Engineering & Construction Management Phone /Fax: (360) 793-9659 28119 - 120th St. S.E., Monroe, WA 98272 E-Mail: rheide@dbsmonroe.com COMPLIES WITH APPLICABLE CITY STORMWATER CODE 03/20/2024 2/195 New House at 1050 Walnut 5t. Edmonds, WA TABLE OF CONTENTS MR 1 — Targeted Stormwater Site Plan Narrative 1. Project Overview and Executive Summary 2. Drainage Information Summary Form 3. Existing Conditions Summary 4. Off -Site Analysis and Mitigation 5. Upstream Analysis 6. Downstream Analysis 7. Flow Control Threshold Evaluation & Developed Site Hydrology MR 2 — SWPPP Narrative MR 3 — Water Pollution Source Control for New Development MR 4 — Preservation of Natural Drainage Systems and Outfalls and Provisions of Off -Site Mitigation MR 5 — On -Site Stormwater Management Appendix: Site Map, Basin Map, Calculations and Sketch Area Topo Map, and SCS Map Photographs Infiltration Trench Design and WWHM Output Schematic Drainage System Design Sketch of Proposed System Soil Management Plan -Compost and Topsoil Checklist Operations Manual — BMP's Ryner-Raman Category 1 Drainage Plan Page 2 3/195 MR 1 - Full Stormwater Site Plan Narrative 1. Project Overview and Executive Summary The lot is 0.15 with an existing driveway south off Walnut St. The existing driveway is partially on the lot to the west based on the survey for this lot. This will be sawcut at the property line or removed in co-operation with the neighbor. The lot slopes to the north and to the west. The project scope is replacement of the existing house, sidewalk and driveway with a new residence and associated access drive and parking. The unmitigated area for the new and replacement impervious is 4,555 Sf and the PGIS is 586 Sf on -site. All possible new and replacement hard surface is being infiltrated with 316 Sf not being infiltrated. This exclusion includes the replacement sidewalk in the R/W. Water quality measures being proposed and identified in the Stormwater Pollution Prevention Plan (SWPPP). As a residential project it is exempt from meeting Minimum Requirement 3 (Source Control) with the exception of S411 BMPs for Landscaping and Lawn/Vegetation Management which is included in the appendix. BMP T5.10A will provide treatment and infiltration of the new/replaced parking. There is a single drainage basin sloping to the northwest and north to the street. Any flow off -site is sheetflow to the road drainage system with inlet CB on Walnut St. 110' to the west. The sketch of the schematic drainage system design proposed for the development shows downspouts and the new parking to an infiltration trench. The upstream and downstream analysis show no key issues or limitations. Detention and infiltration sizing was done using WWHM and all new and replacement on -site areas. Infiltration rate was determined by on -site small pit test by the Geotech. Results are in the appendix. Conveyance sizing was prescriptive based on minimum DOE details. 6" diameter PVC storm and infiltration pipe and 4" PVC pipe for the downspouts. Site planning does not require Minimum Requirement 6 (Runoff Treatment) as the PGIS area of 586 Sf on -site and 432 Sf off -site, total 1,021 Sf is less than 5,000 Sf, Minimum Requirement 7 (Flow Control) as the overall impervious area of 4,555 Sf is less than 5,000 Sf, or Minimum Requirement 8 (Wetlands Protection) as no flows are being concentrated or diverted to or from any known wetlands. Ryner-Raman Category 1 Drainage Plan Page 3 4/195 Drainage Information Summary Form — Only Required for MR7 Flow Control. Not required this project. Project Total Area: 0.15 Acres Project Development Area: 0.15 Acres Number of Lots (if applies): N/A Drainage Basin Information Individual Basin Information A B C D On -Site Sub -basin Area acres Type of Storage Proposed Approx. Live Storage Volume (cu. ft. Approx. Dead Storage Volume (cu. ft. Soil Type(s) (Natural Resource Conservation Service Pre -developed Runoff Rates Q cfs. 2 yr. 10 yr. 50 yr. Redevelopment Area Post -development Runoff Rates without quantity controls Q cfs. 2 yr. 10 yr. 50 yr. Post -development Runoff Rates with quantity controls Q cfs. 2 yr. 10 yr. 50 yr. Offsite Upstream Area Number of acres Offsite Downstream Flow Q cfs. 50 yr. Ryner-Raman Category 1 Drainage Plan Page 4 5/195 3. Existing Conditions Summary The existing conditions are a moderately sloping lot 6,611 Sf Lot with a slope from off -site to the southwest and west onto the lot to the west. The existing house roof is about 2,327 Sf with a 1,229 Sf driveway with walkway to back, a 734 Sf walkway and 122 Sf shed for a total of under 4,412 Sf of existing impervious. The yard is primarily lawn with shrubs and a tree as shown on the site plan. The site is mapped as having Everett -Urban land complex. The soils were evaluated in the Geotech Report. Infiltration was determined to be feasible with a Small Pit test by the Geotech who determine the measured infiltration rate was 4.2 in/hr. 4. Off -site Analysis and Mitigation Existing Impervious: House Roof: 2,327 Sf Shed Roof: 122 Sf Walkway: 734 Sf D/W-Parking(PGHS): 1,229 Sf ------------- Total Existing Hard Surface: 41412 Sf 67 % of Site Proposed New/Replacement Impervious: House Roof: 2,537 Sf Covered Back Patio: 142 Sf Walkway/Back Patio: 858 Sf D/W-Parking(PGIS): 586 Sf Total Proposed On -Site Hard Surface: 4,123 Sf 62 % of Site The roof area is being infiltrated so this will not be effective. There is no effective impervious area on -site. There is 316 Sf of replacement sidewalk where the driveway is being moved. All New Roof & Driveway Surface is mitigated With BMP T5.10A. Ryner-Raman Category 1 Drainage Plan Page 5 6/195 5. Upstream Analysis There are no upstream areas contributing to the site. The site is on a slight knoll. The analysis does not include proposed mitigation per as no significant drainage impacts from the development or redevelopment activity were identified in the upstream analysis. 6. Downstream Analysis The downstream from the property is sheetflow north into the curb flowing west, or off -site to the west and then the flow travels north to the street drainage system. There is a catch basin about 1 10'west of the NW property corner which is where all flows enter the City Storm Drainage System. Flow from this catch basin travels about 1,120' to the west to 9t" Ave to a manhole where the system turns and runs north along the east side of the street. The'/ mile point downstream from the site is between Walnut St. and Alder St. along 9tn Given the reduction in site impervious by infiltrating the driveway and roof surfaces, the impact off site should not be noticeable as most of the flow is in the City Storm System. The downstream drainage facilities should continue to be adequate to accommodate flows from the development activity. The analysis does not include any proposed mitigation as no significant drainage impacts from the development or redevelopment activities were identified in the downstream or upstream analysis. The proposed drainage facilities are designed so that stormwater enters and exits the site at the existing location(s) for entry and exit. 7. Flow Control Threshold Evaluation & Developed Site Hydrology As the proposed new and redevelopment PGIS area of 1,021 Sf is less than 5,000 Sf MR6 does not require structures for water quality treatment. BMP T5.10A Infiltration, will address flows for the PGIS on -site. Off -site flows will travel to the City Street Drainage system. As the overall new and replacement impervious area of 4,555 Sf is less than 5,000 Sf, all impervious is to be addressed with BMP's. BMP T5.10A (Infiltration) were selected to mitigate all new flows. Ryner-Raman Category 1 Drainage Plan Page 6 7/195 MR 2 SWPPP Narrative The project is demolition of an existing house (this is a separate permit) and construction of a new residence at 1050 Walnut Street, Edmonds. Given the new construction the majority of the lot will be disturbed at some point. There is an infiltration trench proposed for the driveway on -site and roof water. This area will require protection during construction. 13 Required Elements - Construction Stormwater Pollution Prevention Plan 1. Mark Clearing Limits: Prior to any clearing or disturbing the limits must be marked. BMP's to be used are: BMP C101: Preserving Natural Vegetation as possible. BMP C102: Buffer Zones as possible. BMP C103: High -Visibility Fence at infiltration trench area. BMP C233: Silt Fence at project perimeter as shown on the plan. 2. Establish Construction Access: The existing driveway can be used for construction access. BMP C105: Stabilized Construction Access can be considered if the driveway proves inadequate. 3. Detain Flows: Flow detention will not be necessary given the flat site. The primary work is installation of the new building. Flows are being dispersed. Flows are to be spread out before contacting silt fence at the edge of disturbance. Other BMP's to be considered during construction as applicable are: BMP C207: Check Dams BMP C209: Outlet Protection BMP C235: Wattles 4. Install Sediment Controls: If there is runoff from the construction site, sediment shall be removed from the water. Water quality standards must be met. Ryner-Raman Category 1 Drainage Plan Page 7 8/195 Silt fence is to be installed and maintained and a Vegetated Strip at the edge of disturbance as much as possible during construction. BMP C233: Silt Fence BMP C234: Vegetated Strip 5. Stabilize Soils: All exposed and non -worked soil shall be stabilized by use of BMP's. This can include temporary 6" high by 12" wide Compost Berms at the edge of disturbance, straw (C121) and/or hydroseed (C120). BMP C120: Temporary and Permanent Seeding BMP C121: Mulching Other BMP's to be considered during construction as applicable are: BMP C124: Sodding BMP C125: Topsoiling / Composting BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection BMP C130: Surface Roughening BMP C131: Gradient Terraces BMP C140: Dust Control 6. Protect Slopes: Any temporary cut and fill slopes need to be protected from erosive flows and concentrated flows until permanent cover and drainage conveyance systems are in place. Plastic sheeting or mats (C123) are to be used as necessary prior to hydroseeding and planting. BMP C123: Plastic Covering Other BMP's to be considered during construction as applicable are: BMP C120: Temporary and Permanent Seeding BMP C121: Mulching BMP C122: Nets and Blankets BMP C124: Sodding Ryner-Raman Category 1 Drainage Plan Page 8 9/195 BMP C130: Surface Roughening BMP C131: Gradient Terraces BMP C200: Interceptor Dike and Swale BMP C201: Grass -Lined Channels BMP C203: Water Bars BMP C204: Pipe Slope Drains BMP C205: Subsurface Drains BMP C206: Level Spreader BMP C207: Check Dams BMP C208: Triangular Silt Dike (TSD) 7. Protect Drain Inlets: Catch basins downstream should have silt socks per COE ER-902 installed or as additionally required by the city. BMP C220: Inlet Protection a. Protect all storm drain inlets made operable during construction so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. b. Clean or remove and replace inlet protection devices when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer). 8. Stabilize Channels and Outlets: Temporary and permanent conveyance systems shall be stabilized to prevent erosion during and after construction. No channels or outlets from the site are proposed other than Piped Storm Drainage. Sheetflow and dispersion is the primary means of dispersing flows. Other BMP's to be considered during construction if applicable are: BMP C122: Nets and Blankets BMP C202: Riprap Channel Lining Ryner-Raman Category 1 Drainage Plan Page 9 10/195 The best method for stabilizing channels is to completely line the channel with BMP C122: Nets and Blankets first, then add BMP C207: Check Dams as necessary to function as an anchor and to slow the flow of water. 9. Control Pollutants: The plan for all pollutants, including waste materials and demolition debris, is that they will be removed from site and properly disposed of. This includes proper maintenance of construction equipment, and application of fertilizers. There is no proposed application of chemicals, or use of water treatment systems. BMP C151: Concrete Handling BMP C152: Sawcutting and Surfacing Pollution Prevention BMP C153: Material Delivery, Storage, and Containment BMP C154: Concrete Washout Area BMP C250: Construction Stormwater Chemical Treatment BMP C251: Construction Stormwater Filtration BMP C252: Treating and Disposing of High pH Water BMP S419: Mobile Fueling of Vehicles 10. Control De -Watering: No dewatering is proposed. If this becomes necessary the water from de -watering systems for any trenches, or foundations shall be discharged into a controlled system. a. Discharge foundation, vault, and trench dewatering water, which have similar characteristics to stormwater runoff at the site, into a controlled conveyance system before dis-charge to BMP C240: Sediment Trap or BMP C241: Sediment Pond (Temporary). b. Discharge clean, non -turbid dewatering water, such as well -point ground water, to systems tributary to, or directly into surface waters of the State, as specified in Element 8: Stabilize Channels and Outlets, provided the dewatering flow does not cause erosion or flooding of receiving waters. Do not route clean dewatering water through stormwater sediment BMPs. Note that "surface waters of the State" may exist on a construction site as well as off site; for example, a creek running through a site. c. Handle highly turbid or otherwise contaminated dewatering water separately from storm water. Ryner-Raman Category 1 Drainage Plan Page 10 11/195 d. Other dewatering treatment or disposal options may include: i. Infiltration. ii. Transport off site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters. iii. Ecology -approved on -site chemical treatment or other suitable treatment technologies. iv. Sanitary or combined sewer discharge with local sewer district approval, if there is no other option. V. Use of a sedimentation bag that discharges to a ditch or swale for small volumes of localized dewatering. If Dewatering becomes necessary, the following BMPs should be considered. BMP C203: Water Bars BMP C236: Vegetative Filtration 11. Maintain BMPs: The inspection and maintenance of the planned and installed construction BMPs shall be done as required after any measurable rain events. Spare silt fence shall be kept on site along with applicable installation construction equipment. All BMPs shall be removed at the end of the project and properly disposed of. BMP C150: Materials on Hand BMP C160: Certified Erosion and Sediment Control Lead -The site is under 1 acre so this is not required but should be considered if available. 12. Manage the Project: The site shall be managed for erosion control at all times. One of the most important elements in the management of the project is planning for contingencies based on the risk of exposure during phases of the development. It is essential that planning is ongoing throughout the life of the project. The project manager must ensure that the project is built in such a way to comply with all Construction SWPPP Elements, as detailed in this section. Considerations for the project manager include, but are not limited to: • construction phasing • seasonal work limitations • coordination with utilities and other contractors • inspection Ryner-Raman Category 1 Drainage Plan Page 11 12/195 • monitoring • maintaining an updated construction SWPPP BMP's to be used are: BMP C150: Materials on Hand BMP C162: Scheduling Not required for this project but should be considered if available. BMP C160: Certified Erosion and Sediment Control Lead 13. Protect On -site Stormwater Management BMPs from roofs and other hard surfaces. C102 Buffer Zones and C103 High visibility Plastic or Metal Fence (C103) are to be used to minimize disturbance in Downspout infiltration or Driveway/Walkway (Infiltration) areas. Suggested BMPs for Element 13 are to be used to minimize disturbance in Downspout infiltration or Driveway/Walkway (infiltration) areas BMP C102: Buffer Zones BMP C103: High -Visibility Fence as specified at site boundaries: BMP C233: Silt Fence Not Required but should be considered if site conditions change: BMP C200: Interceptor Dike and Swale BMP C201: Grass -Lined Channels BMP C207: Check Dams BMP C208: Triangular Silt Dike (TSD) BMP C231: Brush Barrier BMP C234: Vegetated Strip Ryner-Raman Category 1 Drainage Plan Page 12 13/195 MR 3 — Water Pollution Source Control for New Development This is a typical residential site which typically does not have source control BMP's that apply to it. None are proposed other than S411 BMPs for Landscaping and LawnNegetation Management included in the appendix which is required by ECDC. MR 4 — Preservation of Natural Drainage Systems and Outfalls, and Provisions of Off -Site Mitigation Any discharges to the site will continue to occur as sheetflow. Site flows will be captured and routed to the BMP T5.10A Infiltration Trench system on -site. Energy dissipation is provided in accordance with the DOE Manual through sheetflow and infiltration. No mitigation for off -site drainage impacts is required. MR 5 — On -Site Stormwater Management As required the project has chosen to meet the LID Performance Standard instead of using the list approach. The site was evaluated for infiltration. The soil is Everett and was evaluated by the Geotech firm Cobalt. In the Geotech Report it was determined that this site has the potential for infiltration with no water or mottling noted to the depth of the 8' deep test pit. A small pit infiltration test was done that showed the Site infiltration rate was 4.2 in/hr. which was adjusted by the Geotech with a factor of safety of 3.7 to 1.134 in/hr. for design. WWHM was used to size the infiltration trench at 3.33'w x38'L x2' deep for all on -site impervious surfaces, and 116 Sf of off -site driveway that is being taken to the required catch basin before the trench. The Geotech evaluation, test pit log, and WWHM output showing the infiltration trench meets the LID Standard is included in the appendix. The WWHM example provided by Jerry Shuster was used to put the revised WWHM report together. As most of the trench is under the driveway, I did not check the "precipitation to be applied to the trench" but instead added an area of lawn equal to the area of trench out of the impervious surfaces to add that area to the model as required. Calculations for BMP T5.13 Post Construction Soils Quality and Depth were done, and treatment is specified for disturbed areas. Topsoil addition is proposed with a minimum of 62 CY of topsoil required to be added per the City of Edmonds Requirements. 3" placed over the soil disturbed surfaces and tilled in and then another 3" added over the tilled surface. Ryner-Raman Category 1 Drainage Plan Page 13 14/195 Appendix: Site Map, Basin Map, Calculations and Sketch Ryner-Raman Category 1 Drainage Plan Page 14 Raman 1050 Walnut St. Hard Surface Areas �I Ex. Driveway 3. 3313 Ex. 10' Sa r E.MdI 1 AFN: 8206280085 � Prop. 4. S... Ea t. Ja R -rd.d Pr,w to —It Fhol R. eplacement ^^ Off —site Sidewalk Off Site $16 S.f. D/W 116 S.f. To Infiltration Prop. Clearing Limit 7,044 S.f. Prop. on —site Prop. Driveway Driveway 586 S.f. 1021 S.f. r--------1 --� Lawn 26 S.f. To Infiltration Prop. SFR Roof 2,537 S.f. Prop. Covered Entry / Patio 142 S.f. Prop. Concrete Patio & Walklkry 858 S.f. I GRAPHIC SCALE 0 10 20 NORTH (IN FEET) 1 /4/23 1 inch = 20 ft. 16/195 Design Build Services, Inc. Engineering and Construction Management 28119 - 120th 5t. 5.E., Monroe, WA 98272 Phone/Fax #(560) 795-9659 rheide@dbomonroezom Project Name: Project Addreoo: Project Property Tax Number: Project Area: Soil Type(NKC5): Proposed New Impervious: Ryner Homes - Raman 1050 Walnut St. Edmonds, WA 98020-3336 004342-035-015-00 6611 Sf 0.15 Acres 17 Everett Infiltration Roof (SFR & covered Patio): Infiltrated -Not eff 2537 Sf Covered Patio 142 Sf Walkway/Back Patio 858 Sf 3537 Sf D/W-Parking(PGIS): (On -Site) 586 Sf Total New Impervious On -Site 4123 Sf D/W-Sidewalk(PGIS): (Off -Site) 316 D/W-Parking(PGIS): (Off -Site) (Infiltrated On -site) 116 Sf 432 Total New/Replacement Impervious 4555 Sf Not Infiltrated -Effective New Impervious 316 Sf Downspouts to Infiltration Grading Cut SF FT House Foundation 2155, 1.5 Patios 950 1 Walkway/D/W 1169 0.5 Fill 1169 0.33 Compost Amendment Area of Disturbance 7044;SF Impervious Subtracted 4555 SF Drainfield area Subtracted SF 2489 SF Topsoil 25xArea/1000 Sf 62 CY Group A See Geotech/WWHM Infiltrated 2537 Sf 142 Sf 858 Sf 586 Sf 116 Sf 4239 Category 1 3232.5 CF 950 CF 585 CF 177 CY 386 CF 191 CY 0.16 Acres A PORTION OF THE S.W. 1 /4 OF THE S.E. 1 /4 OF SECTION 24, TOWNSHIP 27 NORTH, RANGE 03 EAST, IN SNOHOMISH COUNTY, WASHINGTON 17/195 TAX ACCOUNT NUMBER 004342-035-015-00 Zoning: RS-6 LEGAL DESCRIPTION CITY OF EDMONDS BLI( 035 D-00 - E LOFT LOT 15 & ALL LOT 16 & W 20FT LOT17 NOTES Owner/Applicant/Contact: Eric Ryner Ryner Homes 4224 211" Ave. SE Snohomish, WA 98290 (425) 328-5617 erlcOrynerhomas.com Site Address: 1050 Walnut St. Edmonds, WA 98020-3336 Utility Purveyor: City of Edmonds Public Works & Utilities Administration 7110 210°i St. SW Edmonds, WA 98026 (425) 771-0235 pwO.dmandswo.gov CLEARING 7,044 Sf-0.16 acres HARD SURFACES Sheet Flow Drainage to the Northwest Lot Area 6,611 Sf 0.15 Acres Impervious; Existing House Roof: 2,327 Sf Shed Roof: 122 Sf Walkway. 734 Sf D/W-Parking(PGHS): 1,229 Sf Total Existing Impervious: 4.412 Sf 67 % of Site Proposed New Impervious On -Site• SFR/Patlo Roof: 2,537 Sf Covered Patio: 142 Sf Walkway/Back Patio: 858 Sf D/W-Parking On-Site(PGHS): 586 Sf Total Proposed On -Site Impervious: 4,123 Sf 62 % of Site Proposed New Impervious Off -Site: D/W-Parking Off-Site(PGHS): 116 Sf D/W-Sidewalk Off-Slte(PGHS); 316 Sf Total Proposed Project Impervious: 4.555 Sf All New Roof & Driveway Surface Mitigated With BMP T5.10A DATUM NAVD 88 Elevations shown on this Drawing Were Derived from Information Provided by WCCS Survey Control Database. The Mark is a 1 %" Domed Brass Disk Down 0.8 3 140' south of the intersection of Walnut Street and 9th Avenue South. Point ID No. 2703R23; Elevation 281.273 Feet - NAVD 88 2.0' Contour Interval - the Expected vertical Accuracy is equal to the contour interval or plus/minus 1.0' for the Project. EDITION NOTE This Project Has Been Designed to Meet City of Edmonds Drainage Manual July 2022 Edition. GRADING QUANTITIES Site Grading: Cut: 177 CY from site and foundation. Fill: 191 CY will be backfilled around & under parking/drive per site plan. Any excess cut will go to an approved dumb site as stated in note 2, 62 CY of topsail placed over disturbed areas 6' deep per BMP T5.13 in area of disturbance outside Impervious areas only. Refer to City of Edmonds handout JE72 C table 1, option 2. Table on Sheet 3. NOTES: 1. No correction for soil expansion or unsuitable material has been made. Contractor Is responsible for oil earthwork estimates used for cost purposes. 2. Excess cut yardage not used for fill per the approved plans shall be disposed of at a permitted site or commercial topsoil company. CONSTRUCTION SEQUENCE NOTES 1. SCHEDULE PRE —CON MEETING WITH THE CITY OF EDMONDS SITE INSPECTOR THROUGH My6,VdhgPermTt c AND EMAIL _9Ih dngpermlt.0.drn-d.wa.gov 2 DAYS (MINIMUM) IN ADVANCE OF DATE REOUESTEO. 2. REVIEW TEMPORARY EROSION AND SEDIMENT CONTROL NOTES. 3. CALL FOR UTILITY LOCATES. 4. INSTALL TESC MEASURES AND MAINTAIN DUST CONTROL WHILE PREVENTING DISTURBANCE OF ANY AREAS OF VEGETATION OUTSIDE THE CONSTRUCTION ZONE. 5. HAVE EROSION CONTROL MEASURES INSPECTED BY CITY OF ED MONDS ENGINEERING INSPECTOR. ALL TEMPORARY SEDIMENTATION AND EROSION CONTROL MEASURES MUST BE IN PLACE AND INSPECTED PRIOR TO ANY CONSTRUCTION OR SITE CLEARING. EROSION AND SEDIMENTATION CONTROL PRACTICES AND/OR DEVICES SHALL BE MAINTAINED UNTIL PERMANENT VEGETATION IS ESTABLISHED. 6. DEMOLISH EXISTING STRUCTURES (SEPARATE DEMO PERMIT) 7. CLEAR, GRUB, AND ROUGH GRADE SITE AS REQUIRED TO INSTALL NEW SFR AND DRAINAGE FEATURES 8. FINAL GRADE SITE, REVEGETATE DISTURBED AREAS NOT SUBJECT TO ADDITIONAL SURFACE DISTURBANCE IMMEDIATELY AFTER ROUGH GRADING. (OTHER EXPOSED AREAS SHALL BE STABIUZED PER EROSION CONTROL NOTES ON SHEET 3) 9. INSTALL UTILITIES AND OTHER SITE IMPROVEMENTS, INCLUDING D/W AND FRONTAGE IMPROVEMENTS. 10. STABIUZE AND COMPOST AMEND ALL EXPOSED SOILS PRIOR TO REVEGETATION OF ENTIRE SITE. 11. ESTABUSH LANDSCAPING AND PERMANENT VEGETATION. ALL TEMPORARY EROSION CONTROL MEASURES SHALL BE REMOVED UPON FINAL SITE STABILIZATION AND APPROVAL BY CITY INSPECTOR. HAUL ROUTE Walnut west to 9°' Ave S then south to Edmonds Way then SE to Ballenger Way then East to 1-5 LEGEND - - - - - - - - Right of Way Line ----- Center Line - - - - - - - - - Adjacent Lot Line -- - - - Existing Easement Line --JIa--- Existing Contour Line Existing Fence -------- Exist(ng Gravel Drive Existing Building ----------------- Existing Roof - — Existing Sewer Line (Wet Utility) OExisting Sewer Manhole (Wet Utility) —�—�— Existing Water Line (Wet Utility) ❑ Existing Water Meter (Wet Utility) Existing Gas Line (Dry Utility) Existing Overhead Power Line (Dry Utility) Existing Power Pole (Dry Utility) ® Existing Power Meter (Dry Utility) Existing Flow Arrow o _ Existing Tree —�(x- Existing 14' Tree Protection Line TP Geotech Test Pit Location Existing Concrete Drive, Parking, Walks, and Patios Driveway Approach and Curb Development /.-..-./--.-/.-.. and Restoration Arco KEYED NOTES Evle Nng SIT. Ie to be demdf.hed — asp Ora to permit OEzi.Ung Rood OExle Ung Concrete Sidewalk O3 EzlW g off Slte Home ® Existing Concrete (a) Driveway & Padeing (b) Cov... d Pocking (c) Wekway $� Evleting Single Family Residence © Exisling Shed O7 E.i.Ung Retadnhg Wdl © E.ietinq Ftnce OExie ting Owrh.od (a) Power Line & Pde (b) Power Una to SFR to be removal Exlstlnq Water Lhe. Etleting %r ce to be relocao ted ea.t out of the new driveway a. 11 Ezls ConCon Sewet. r Llne (a) necto Ewislinq home QExieRng Goe Line 1® Ezis Unq Tree(See Sht 3) ' 11 SSMH RIM=318.5 ' INN E—W-5=311.93' 11 11 - — --y — —=�- — — --5 ---- 1 rvl SSMH RIM=318.07' 11 n10 INN N-S=3 3.59' n R „Walnut Stleot S—__--_ Ex of 99' Y! of NW rc'=a y I I d Ex. i d D,Iveway 'J I I , ° O Ea. 03 103E of NE Properly Cantu J19] 1 TP ® + B � x 20' E35BL i 1 w r i m o o I �1p m o � Z I m d ° 1 0 I I° I i i a I � 1 e ---------- --- 'i '® I S, E-t- I h 82062800851 I I 11I1\ 6 � I -------`---_�--.. S89' 52' 1 I f j1 270325-00I-123-00 Existing Site 15' BSBL \ q MI II •�:E:ErIn11:S�77 VICINITY MAP SITE CONDITIONS EXISTING DEVELOPED SOILS er E;ett—Urban lond Same 0omplex —8i Slopes FOLIAGE Vagetatbn, SFR, Deck, Some w/New SFR, Patio, Patio, Drive, & Drive & Land.caping Land —ping TERRAIN Flat to eilghtly doping S.— UTILITY PROVIDERS Water: City of Edmonds Utilities Sewer: City of Edmonds Utilities Storm: City of Edmonds Utilities Natural Gas: Puget Sound Energy Electricity. Snohomish PUD Cable: Xfinity Phone: N/A Internet: XfInity Garbage/Recycling/Yard Waste: Sound Disposal O SHEET INDEX Sheet 1 Cover Sheet and Existing Site Plan Sheet 2 Proposed Site, Drainage, & Utility Plan Sheet 3 TESC, SWPPP, Details, & Notes Sheet 4 City of Edmonds Details Sheet 5 City of Edmonds Details Sheet 6 City of Edmonds Detolis GRAPHIC SCALE NORrx N((IN FEET) APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: Call 48 Hours Before You D19 CITY ENGINEERING DIVISION 1-800-424-5555 or 8-1-1 V) Z O V) W cn v\ � L C C L 0m 0 W� U 0 N tXl X b � 5 Q� m 6T 0 lit a--r C O d C .�.r O !n L U N m C O " E> O w �� Lo W] U O C o C) 0 T-- >I L +� m N v c) E U) -C E > O 0 u CNJ U LL A PORTION OF THE S.W. 1/4 OF THE S.E. 1/4 OF SECTION 24, TOWNSHIP 27 NORTH, RANGE 03 EAST, IN SNOHOMISH COUNTY, WASHINGTON 18/195 SSMH RIM=318.5W INV E-W-S=311.93' SS IE 314.99 12* PVC SEWER MAN �- __ . __ S __ e- Cents, Urc Top o(Pipe4�,^-�,-„-. rvI 1 xI a Bottom of Pi 48' SSMH RIM 18.07' ps. Oj Wainu4 Street III N-S= 31,59' O S8-9'1 S 2260' .5' rI{'S/5�--(118^Vp'jE YB 1 e'x18"' Ex. m 99, WA Orate W at III, RIM(=318.0' , "�T"tY IE(S)6'C-90d:3T6.5' BOTTOM" 315.5' I E(N)4"PVC: 31610' 1 11 IEL)4"PVC: 316t1n� I j IE(E)6' PVC: 3610' I ` BOTTOM=3iI4.10' dt � i I COI-D41 C-9C0 6.5'I Ex. Driveway I 14' t % � I I is ly` I I I 0 I a o O 0 n I I I < I I I I O j Is.o: 3 0 II I v � I 1 1 I� 1 II I II I V 1 Ii Ex. 10Sewer Eeml�1 AFN: B20fi2B0085 I I' I 11 Prap. 4' 5.... Es t. 1 \ To be Recorded Prier to mit FIn4 _-_---_1_-_ I I! N LIMMAWAS �a 3i35 319'� 8 II. Er.La 103'Eof V 16 NE PropvtY ccm er ✓/IIVVVII,ry�1\ O • N X 7 GRAPHIC SCALE 1 I f0 - Na0.TH (IN� 9. O a .\ 0 n 0 a 2 0 3 1 LO, Pd P11 'a 1@a I I 270325-001-123-00 I Proposed Site LEGEND - - - - - - - - Right of Way Line Proposed Footing Drains Proposed Underground Power Line (Dry Utility) -- Center Line ------------------ Proposed Drainage Lines - - - - - - - - - Adjacent Lot Line -, -, Existing Sewer Line (Wet Utility) Q- Existing Flow Arrow - - - - - - - - - Existing Easement Line -. -. Proposed Sewer Line (Wet Utility) F Proposed Flow Arrow ----Jrs ---- Existing Contour Line O Existing Sewer Manhole (Wet Utility) J19' + Proposed Grade Points Jig �r Proposed Centaur Line -'-'-'-'-�-x-s-' Existing Fence -„ -„ - Existing Water Line (Wet Utility) O Existing Tree Proposed Water Line (Wet Utility) --------- Existing Gravel Drive 1E Proposed Water Meter (Wet Utility) Existing Building ---X Existing 14' Tree Protection Line -rs-a..- Existing Gas Line (Dry Utility) Proposed Concrete Drive, Parking, -- Existing Roof -w-w- Proposed Gas Line (Dry Utility) Walks, and Patios - - - - - - - - Proposed Building Lines (Both Floors) Existing Overhead Power Line Utility) ;-J - j�' Driveway Approach and Curb Proposed Roof (Dry ,/./ Development and Restoration Area Existing Power Pole (Dry Utility) KEYED NOTES OExl.ting Road O2 EXleting Cncrete Sld-11, O3 Existtng off Site Home ® Proposed Gas Line OProposed Pavement/Curb cut fw Propo,,d Drlvwwoy and Curb Replacement. Extent to be confirmed by the City of Edmond. Inspector at Pre -Con. See re storatin note. © FaoI D,,;,, to 4' diameter x 4' deep dryw.li for footing drains any per details SO-63B an Sheet 6. Cnneclln shop be at least 10-tt away ham the home. For fooling dralne, perf pipe only around house and Then said pipe for c yance. The system shall be a minimum of to' from the structure. OExisling Fence OExts Ung Overhead P.- Line & Pole Og Rd... to Water Lune and Meter out of Driveway ® ExTeting 6' Sewer Llne-w/ CD per SS-2DO. 11 4"0 PVCStorm Water PIP- Sloped at l% MIn as Shown per SD-fii9 an Sheet 5. Use Du cflI Iron & C-900 where 1' oan f ldscape co or 2' of driveway cover Is not ovaliable. vw, 11a Proposed 35' Long Infglrot].n Trench-3.33' wide for Roof Downpouts/DHveway/Parking/Patla using Deal SD-fi 36 on Sheet 5. Bottom of Trench O 315.13' QProposed Driveway & poking to replace Existing Driveway. Proposed elope of O%-6X Slope .21 not exceed m than 14X per ECDC 18.80.ufi D. Per ECDC 17.60.040we Driveway shot not be wlde, then 24ft. ® Proposed SFR to Replace Exl,fing Home ®Proposed Walkway wound West aide of Prop... d STR to II Patio © Proposed Pal]. (a) not covered (b) covered 16 Proposed Underground Power/Cable & Telephone Lines. The a2wist Ie to be aalt.d prior to line in.tollatlon and if sa.ry The line. will be bored through the Ire. pr.,.."_ circle. © Proposed V Water Meter le to be installed to replace Existing i' Water Meter O PA per CITY. ® Prop ... d 1-}' Schedule 40 PVC Water Serdce Dne Is to be installed from the back of Proposed Water Meter to House. Traces Mr. wll be ""startled as well. Water IIna to be sleeved under the be trench, 7g 4' SDR35 Sewer line to be run between the existing SS 6' Side sewer clean -out at the street and line portion of the side sewer under The tree, avvi0lng Impact to (he ex3sthg tree, ond a new line and dean -out lase lhn 2' from the e w house to be In,toi The new 4''In. shall dope of m lnimam of 2_% as shown in SS-2DO. Portion of rernoining SS to be Inspected per Utility Nate 5. ® Cut and Patch Ulllltie. In R/W per City Standard Details GU-400 and GU-41D QOb-tion Wall ® Roof Linea ® 14' Tree Protection Circle - Size to be con Binned by the Arb wl.t In association with Utility Insldlatin. FRONTAGE IMPROVEMENT NOTES Any existing fronitage knprav-ts that are foiling, damaged n-ADS pllonl Mail be removed and replaced as determined by the City Engineering Inspector. GRADING 8r DRAI NAGE INAGE NOTES Lot Is fo be graded far new building, driI . oy parking and polka to be placed a. Mown. This Is line only grading prop Dee d. Stockpiles to Be Covered In 24 Hours. Roof dlschorge w11 be downspout. to 4" PVC Pipe andClean-ou to per SO-619 and an Infgtratlan Trench per SD-636 and section deign. Any disturbed or... outside proposed Imp,Mo Is to have 6' of topsoil placed - at disturbed areas per BMP T5.13. Estimated for p r op ..d dietarbance I. 62 CY. Refer to City of Edmonds handout JE72 C table 1, option 2. If the rim to Invert eI-ttan exceed. 5-feet then a type II ma�nh ale wTit be required. A special Inspection from the Gaot,ch will be equlred for any area. where the a:n,l,cun antra... L, 1...led e the elan"etl in ll it trench. This le to e Thai the oil, at the base of the Inmtratin U ensure ore able to hBltrote at the sp. 111,d ufelration rate. RESTORATION NOTES R..tor.Uan of Wllly path.. a. fellows: 1. Utility pot"'as wtlh lee. lhon 2D-feet of sap era Lion eholl be combined and fall idh w half width overlay will be required depantling the eXte.nt f dletu rbance. Where unity Patehes fall entirely within one travel lane, the overlay shall extend to the ce twit,, of roadway. "are utility path,, extend Into bath travel Ines than a fuu width overlay. 1, r,qulred. 1. AI" final restoration within the igh t-af-way shell be completed by the contractor mat the City of Edmunds. III. Asphalt cuts far the cub a Mown n fhe plea a expected. Any required asphalt cute shod be vartPIZ and Identified at the Pre -Con meeting. Final rest ... lion squired by the COE will be det.min.d Fartng r,s tar.U.n In.p.ction. iv. The City will cvt and move the water aerdce line for the ..I.ting water m ter at the main; howeve r, the d evdoper of the subject ens will be re,paneibla for tin. find reatwallan far the new swdo. being cut and d the at far Th bcappeds then paved sac ll n ofa the raodwoy.law to. l See TIL obove. to UTILITY NOTES T79-minimurn o of horizontal separation is required between Water and sewer lines. 2, All final restoration shall be completed by the contractor not the City of Edmonds. 3. The 6" sewer cleanout at the property line shall have a 12' Cast Iron Lomphole Cover with }� He Bolts, o Pick Hole, and a Concrete Collar, 4. A sewer cleanout Is required to be located within 2' of the house, at any 90' bend, and when there is less than 3' between two 45' bends. 5. As the existing sewer lateral is proposed to be reused, the Citys Public Works Deportment will need to TV the lateral to determine if it is acceptable to re -use. CONTRACTOR TO CONTACT EDMONDS AT engineeringpermits®edmondswo.gov TO SCHEDULE AN INSPECTION OF THE SEWER LATERAL. 6. Alf dry and wet utilities are shown and required utility separation met. A minimum of 3' horizontal separation & 1' vertical separation is required between the dry utilities (power, gas, phone, cable, etc.) and wet utllities (sewer, water, and storm). Dry utilities must be 5 feet from any City main lines. GENERAL NOTES 1. ALL MATERIALS AND WORK SHOWN ON THESE PLANS SHALL CONFORM TO THE CITY OF EDMONDS STANDARD PLANS AND DETAILS, THE FOLLOWING SPECIFICATIONS AND CODES, AND ALL OTHER APPUCABLE LOCAL MUNICIPAL, STATE, AND FEDERAL CODES, RULES AND REGULATIONS: - CURRENT CITY OF EDMONDS DRAINAGE MANUAL CURRENT INTERNATIONAL BUILDING CODE (IBC) CURRENT WSDOT/APWA STANDARD SPECIFICATIONS FOR ROAD, BRIDGE AND MUNICIPAL CONSTRUCTION 2. STANDARD PLAN AND TYPE NUMBERS INDICATED ON THESE DRAWINGS RUM TO CITY OF EDMONDS STANDARD DETAILS, UNLESS NOTED OTHERWISE J. A COPY OF THESE APPROVED PLANS MUST BE ON THE JOBSITE WHENEVER CONSTRUCTION IS IN PROGRESS. 4. DEMOTIONS FROM THESE PLANS MUST BE APPROVED BY THE ENGINEER OF RECORD AND THE LOCAL GOVERNING AUTHORITY. 5. CONTRACTOR SHALL RECORD ALL APPROVED DEVIATIONS FROM THESE PLAN 4 ON A SET OF AS -BUILT' DRAWINGS AND SHALL SUMMARIZE ALL AS - BUILT CONDITIONS ON ONE SET OF REPRODUCIBLE DRAWINGS FOR SUBMITTAL TO THE OWNER PRIOR PROJECT COMPLETION AND ACCEPTANCE. A SET OF AS -BUILT DRAWINGS SHALL BE SUBMITTEO TO THE CITY OF EDMONDS PRIOR TO FINAL APPROVAL OF THE BUILDING OCCUPANCY/FINAL PROJECT APPROVAL Si ELEVATIONS SHOWN ARE IN FEET, SEE SURVEY FOR BENCHMARK INFORMATION, 7. THE LOCATIONS OF EXISTING UTIUTIES AND SITE FEATURES SHOWN HEREON HAVE BEEN FURNISHED BY OTHERS BY FIELD SURVEY OR OBTAINED FROM AVAILABLE RECOROS AND SHOULD THEREFORE BE CONSIDEREO APPROXIMATE ONLY AND NOT NECESSARILY COMPLETE. IT IS E S lE THE SOL RESPINDEPENDENT Y OF THE CONTRACTOR TO LOCATIONS SHOWN VERIFY THE ACCURACY OF ALL AND LOCATIONS SHOWN AND TO FURTHER DISCOVER AND PROTECT ANY OTHER TE DBy NOT SHOWN HEREON WHICH MAY BE AFFECTED BY THE IMPLEMENTATION OF THIS PLAN. CONTRACTOR SHALL VERIFY LOCATION, DEPTH, SIZE, TYPE AND CONDITION OF EXISTING NC OUTIUTY RE ONES AT CONNECTION TK CROSSING ENGINEER BEFORE TRENCHING FOR NEW UTILITIES. ENGINEER ASSUMES NO RESPONSIBILITY FOR THE COMPLETENESS OR ACCURACY OF THE EXISTING UTILITIES AND STE FEATURES PRESENTED THESE DRAWINGS. LIENGINEER SHALL BE NOTIFIED IMMEDIATELY CO OF CONFLICTS THAT ARISE. 8. CONTRACTOR SHALL LOCATE AND PROTECT ALL UTILITIES DURING CONSTRUCTION MO SHALL CONTACT THE UNDERGROUND UTIUTIES LOCATION SERVICE (1-8001 AT LEAST 48 HOURS PRIOR TO CONSTRUCTION. 9. CONTRACTOR SHALL VERIFY ALL CONDI TIOS AND DIMENSIONS AT THE PROJECT STE BEFORE STARTING WORK AND SHALL NOTIFY OWNER'S REPRESENTATIVE OF ANY DISCREPANCIES. 10. PIPE LENGTHS WHERE SHOWN ARE APPROXIMATE AND MAY CHANGE DUE TO FIELD CONDITIONS. 11. CONTRACTOR SHALL OBTAIN A COPY OF THE GEOTECHNICAL REPORT (WHERE AMICABLE) AND SHALL THOROUGHLY FAMILIARIZE HIMSELF WITH THE CONTENTS THEREOF. ALL SITE WORK SHALL BE PERFORMEO IN STRICT COMPUANCE WATH THE RECOMMENDATIONS OF THIS REPORT. 12. STRUCTURAL FILL MATERIAL AND PLACEMENT SHALL CONFORM TO THE RECOMMENDATIONS OF THE PROJECT GEOTECHNICAL REPORT. 13. SUBGRADE SOILS IN ALL AREAS WHERE RAN GARDENS, INFILTRATION OR PERVIOUS PAVEMENT IS TO BE PLACED SHALL BE DEUNEATED AND PROTECTED AT ALL TIMES FROM COMPACTIVE ACTIVITIES (L.. HEAVY EQUIPMENT, STOCKPIUNG). 14. MANHOLES, CATCH BASINS, UTIUTIES AND PAVEMENT SHALL BEAR ON MECUM DENSE TO VERY DENSE NATIVE SOL OR COMPACTED STRUCTURAL FILL IF SOIL IS DISTURBED, SOFT, LOOSE, WET OR IF ORGANIC MATERIAL IS PRESENT AT SUBGRADE ELEVATION, REMOVE AND REPLACE WATH COMPACTED STRUCTURAL FILL PER GEOTECHNICAL REPORT. GENERAL NOTES ICONT. 15. SEE SURVEY AND ARCHITECTURAL DRAVANGS FOR DIMENSIONS AND LOCATIONS OF BUILDINGS, LANDSCAPED AREAS AND OTHER PROPOSED OR EXISTING SITE FEATURES. 16. SEE ARCHITECTURAL DRAVANGS FOR PERIMETER FOUNDATION DRAINS. FOUNDATION DRAINS SHALL BE INDEPENDENT OF OTHER SITE DRAIN UNES AND SHALL BE TIGHTIJNED TO THE STORM DRAIN SYSTEM WHERE INDICATED ON THE PLANS. 17. ALL REQUIRED STORMWATER FAGUTIES MUST BE CONSTRUCTED ANO IN OPERATION PRIOR TO INSTALLATION OF ANY PAVEMENT UNLESS OTHERWISE APPROVED BY THE ENGINEER. la. ALL ROOF DRAINS, PERIMETER FOUNDATION DRAINS, CATCH BASINS AND OTHER EXTERNAL DRAINS SHALL BE CONNECTED TO THE STORM DRAINAGE SYSTEM, UNLESS NOTED OTHERWISE. 19. ALL FOOTING DRAINS SERVING BUILDINGS, WALLS, ROCKERIES, ETC. SHALL CONNECT TO THE DRAINAGE SYSTEM DOWNSTREAM OF THE SITE STORMWATER MANAGEMENT SYSTEM. ID. CONTRACTOR SHALL OBTAIN AND PAY FOR ALL PERMITS REQUIRED FOR INSTALLATION OF ALL SATE IMPROVEMENTS INDICATED ON THESE DRAWINGS. 21. A SEPARATE IRRIGATION PERMIT MUST BE OBTAINED FROM THE CITY PUBUC WORKS DEPARTMENT. PRIOR TO FINAL CONSTRUCTION ACCEPTANCE, PROVIDE TO THE CITY WATER QUALITY TECHNICIAN, A COPY OF THE BACKFLOW TEST REPORT. TEST REPORTS CAN BE FAXED TO 425-744-6057 OR EMAILED TO JEFF.KOBLYHGEDMONDSWAGOV. BACKFLOW TESTING SHALL BE COMPLETED BY THE OWNER ANNUALLY THEREAFTER. 22. AS A MINIMUM REQUIREMENT. ALL DISTURBED AREAS ON AND OFF SITE SHALL BE RETURNED TO THE EQUIVALENT OF THEIR PRECONSTRUCTION CONDITION IN ACCORDANCE WITH APPROPRIATE REQUIREMENTS AND STANDARDS 2J. ALL DISTURBED SOIL AREAS SHALL BE COMPOST AMENDED AND SEEDED OR STABIUZED BY OTHER ACCEPTABLE METHODS FOR THE PREVENTION OF ON - SITE EROSION AFTER THE COMPLETION OF CONSTRUCTION. SEE EROSION CONTROL PLANS FOR SPECIFIC GRADING AND EROSION CONTROL REQUIREMENTS. 24. THE CONTRACTOR SHALL KEEP OFF -SITE STREETS CLEAN AT ALL TIMES BY SWEEPING. WASHING OF THESE STREETS WALL NOT BE ALLOWED WITHOUT PRIOR APPROVAL 25. THIS PROJECT IS NOT A BALANCED EARTHWORK PROJECT. BOTH EXPORT AND IMPORT OF SOL AND ROCK MATERIALS ARE REWIRED. 2fi. SLOPE OF FINISHED GRADE SHALL BE CONSTANT BE EN FINISHED CONTOURS OR SPOT ELEVATIONS SHOWN. 2- FINISHED GRADE SHALL SLOPE AWAY FROM BUILDING WALLS AT MINIMUM 5% SLOPE FOR A MINIMUM DISTANCE OF 10 FEET. 28. CONTRACTOR SHALL BE RESPONSIBLE FOR AND SHALL INSTALL AND MAINTAIN SHORING AND BRACING AS NECESSARY TO PROTECT WORKERS, EXISTING BUILDINGS, STREETS, WALKWAYS, UTIUTIES AND OTHER EXISTING AND PROPOSED IMPROVEMENTS AND EXCAVATIONS AGAINST LOSS OF GROUND OR CAVING EMBANKMENTS. CONTRACTOR SHALL ALSO BE RESPONSIBLE FOR REMOVAL OF SHORING AND BRACING, AS REQUIRED. 29. CONTRACTOR SHALL OBTAIN APPROVAL FROM THE CITY AND FOLLOW CITY PROCEDURES FOR ALL WATER SERVICE INTERRUPTIONS. HYDRANT SHUTOFFS, STREET CLOSURES OR OTHER ACCESS RESTRICTIONS. CONTRACTOR SHALL NOT RELOCATE OR ELIMINATE ANY HYDRANTS WITHOUT FIRST OBTAINING WRITTEN APPROVAL FROM THE FIRE MARSHAL 30. COORDINATE AND ARRANGE FOR ALL UTIUTY CONNECTIONS, UTIUTY RELOCATIONS AND/OR SERVICE INTERRUPTIONS WATH THE AFFECTED OWNERS AND APPROPRIATE UTILITY COMPANIES. CONNECTIONS TO EXISTING UTIUTIES SHALL BE MADE ONLY WITH ADVANCE WRITTEN APPROVAL OF THE AUTHORITIES GOVERNING SAID UTIUTIES. 31. ALL UTILITIES SHALL BE PLACED UNDERGROUND. 32. EXISTING UTIUTY UNES IN SERVICE WHICH ARE DAMAGED DUE TO CONSTRUGTION WORK SHALL BE REPAIRED AT CONTRACTOR'S EXPENSE AND INSPECTED AND ACCEPTED BY CITY OF EDMONDS AND OWNER'S REPRESENTATIVE PRIOR TO BACKFTWNG. 33, NEW UTIUTY LOCATIONS ARE GENERALLY SHOWN BY DIMENSION, WHERE NO DIMENSIONS ARE INDICATED, LOCATIONS MAY BE SCALED FROM ORAWANGS FIELD ADJUSTMENTS SHALL BE APPROVED BY OWNER'S REPRESENTATIVE AND CITY. 34. FIELD STAKE ALL UTILITY STUBS AT THE PROPERTY UNE. 35. TRENCH BACKFILL OF UTIUTIES LOCATED WITHIN THE CITY RIGHT-OF-WAY SHALL BE COMPACTED TO 951G COMPACTION TEST REPORTS SHALL BE PROVIDED TO THE CITY PRIOR TO PAVING. 36. WHERE NEW PIPE CLEARS AN EXISTING OR NEW UTIUTY BY 6' OR LESS, PLACE ETHAFOAM 2DO AS A CUSHION BETWEEN THE UTIUTIES. 37. SEE MECHANICAL DRAWINGS (WHERE APPUCABLE) FOR CONTINUATION OF SITE UTIUTIES WITHIN THE B UILDiNG. 36. SEE ELECTRICAL DRAWINGS (WHERE APPUCABLE) FOR EXTERIOR ELECTRICAL WORK. 39. SEE LANDSCAPE DRAWINGS (WHERE APPUCABLE) FOR STE IRRIGATION SYSTEM. 40. PIPE MATERIAL AND SIGNAGE SUBMITTALS SHALL BE PROVIDED TO CITY ENGINEERING DIVISION FOR APPROVAL PRIOR TO INSTALLATION. APPROVED APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: Call 48 Hours Before You Dig I BY: 1-800-424-5555 or 8-1-1 CITY ENGINEERING DIVISION 0 Z 0 to K r c n � L � y � CJJ r O U� - U N +z 'L � X nQb CV C I Q) LU C /rI a VI IL C 4 _ O D a, � � C S O 0 0 C: O E0 On , 0 W C C 3 O ° ou � O � S UT O U O O C N in O N CL 0 L L 10 PROJECT NO.22-32263 A PORTION OF THE S.W. 1/4 OF THE S.E. 1/4 OF SECTION 24, TOWNSHIP 27 NORTH, RANGE 03 EAST, IN SNOHOMISH COUNTY, WASHINGTON 19/195 "p cent dins—_—�-- __ F--alnutnStreet BSBL i'^' I' o 0IIn1a:' I N all b —... '' i' o OI 'I' O•• Im.. , I••1. .. 00'01'45"E S89' 52 26 E 50 1------- 270325-001-123-00 Existing Site A SCALE: GRAPHIC SCALE Nl, 0� FEET) N,RTH 1 ±Air 2' . 2' FILTER FABRIC SECURED TO 2" . 2' 14 GA MIRE FABfUC EQUAL NATNE BFCKFTLL FILTER FARRC W A T E R4L IN CO NTINDUS ROLLS USE STAPLES OR WIRE RINGS TO ATTACH FABRIC TO WIRE 2' x 2• WOOD/STEO. POSTS-\ FENCE r FILTER BURY BOTTOM OF FILTER MATERIAL 6' TO 12• NOTESi I. CONTRACTOR/DEVELOPER SNAIL MANTXN AND ENSURE PROPER EROSION CONTROL THRCUGHOUT PROJECT. 2. SILT FENCE TO BE PLACED OOWNSLOPE OF CONSTRUCTION ACTIATY. CITY OF EDMONDS FILTER FILTRAT PUBLIC WORKS DEPARTMENT f=f.ia'do APPROVED BY: Cent L ILA ® - -R—IA— s Walnut Street C, ) 0 589'S5'1 — 60' KEYED NOTES OE.I.ting Home to be Demull.hed (Separate Permit) OExletln9 Shed to be D—NI.hed (SW—te Permit) O3 Exleting Concrete Walkway to be removed (Separate Permit) ® Existing Driveway/Curb to be removed (Sep orate Permit) OE,Isting R.talning Wall to be removed (Sepa.rola Permit) © EA,Iing Tree (DF-Dauglae FT,) to be fenced with Tree Protection 14'e O7 Proposed Driveway & parking to replace Exisling Driveway. Proposed r_ elope of 6S Slope shaft not exceed we than 14% per ECDC 10.80.060. Per ECOC 17.60,040 Driveway .hall not be wider then 24ft. O8 Prop ... d Driveway entrance per TR 541 O9 Pr ...d SFR to Replace Existing Home op P 9 ® Proposed Poll. & Walkway around Westelde of Proposed SIR to Patio 11 Driveway to be used as Temporary Construction Entr,n ca If Needed a Construction Entrance Shall be Installed per Clly of Edmund. Standard DX, ER 901. Temporary Dlrt Stockplle to be Covered within 24 Hours © Silt and Orange Protective Barrie Fencing 1, Required to be In,la}led ® Clearing Limlt,, Area of Dl.lurbanca (7,044 Sf) See Nate Bela. LEGEND ---23� Existing Contour 235�� Proposed Contour F Silt Fence g g x Existing Fencing i— ✓� Clearing & Grading Limits Existing Flow Arrow Proposed Flaw Arrow —�No110.21CLEARING LIMIT NOTES ' ^^--^••:3 r'1 110.21Area of disturbance goes bayon� rap,rty lines due to remaNng of exlating driwwoy and cutting Into aide d� and atrset to Install new driveway. j r I j S89' 5226 E 60 Ali dlaturbed area. to be compact amended per 2D1g SwiVMWW BMP T5.13. 270325-001-123-00 Proposed Site A CATCH BASIN NOTES SCALE: UNINAW GRAPHIC SCALE ee(N� Catch Boslne down the strt will need Temporary Sediment Traps. I0t 1. 2. 20 Flits, Sacks will be added to any Catch Basins Downstream from the �I Con.wctlon Sit.. (IN7. NaRTH GENERAL NOTES =- Install and Maintain all TESC Measures according to approved plans, Cly of Edmond, .told detail., and dl other maowra, that may be required during cone Wetlon. CRY INSPECTION REQUIRED ON ALL EROSION CONTROL METHODS BEFORE OTHER WORK CAN BEGIN REVISION DATE FABRIC FENCE JANUARY 2018 iON SYSTEMS STANDARD D ETAI L R. EGLISH ER-900 GMTE (OYER ) FLOWNHOLES FILTER CATCH BASIN NOTES: 1. COHRRACIOR/DEVELOPER SRALL YAWAIN TNIS AP MoN AT ALL TIMES WRING CONSTRUCUGN PIERIOD, 2. ANY SEDWENT IN CATCH BASIN INSERT SHALL BE REMOVED WHEN NSEffr IS ONE-THM FIAT, 3. CITY INSPECTION REQUIRED ON ALL EROSION CONTROL YETHODS BEFORE OTHER WORK CAN BEGIN, TEMPORARY SEDIMENT TRAP FOR CATCH BASINS APPROVED BY: R. ENOUSH REVISION DATE JANUARY late STANDARD DETAIL ER-902 SWPPP NOTES Reference SWPPP n Drainage Report 13 Raqq bed Element. - Construction Stornwater Pdlutlon Prenerltlan Man I. Nark Clewing Limit, Prlw to any clearing or disturbing the limits must be marked. BMP's to be used we: BMP C101: P...... ing Natural Vegetation o. possible. BMP C102: Buffer Zane. as p... Ibla. BMP C103: High-Vi.bOlty Fence at 61W.U., trench ore,. BMP C233: Silt Fence at project perimeter a. shown an the plop. 2. Establish Construction Access: The existing drfveway should be used fw co ,traction access. If this prove, inadequate then BMP C105: Stab,, lzed Construction Access should be conald... d. 3. Detain Flaws: Flaw detention will at be .....sa.y given the flat site. The primary work Is Inetol otlon of the w building. Flaws a a being dispersed. Floes a e to be spread out before contacting oat fence at the edge of dlaturbo,ca. Not Required far this project: BMP C207: Check Dam. BMP C235: Wattles BMP C209: Outlet Protection 4. Install Sediment Controls: If there le runoff from the a lru !Ion ,its, sediment hall be removed from the wales. Water quality standards must be met. Sit fence 1. to be Installed and maintained and Vegetated SWp of edge of disturbance as p...11. during c—Ln,clion, BMP C233: SIN Fence BMP C234: Vegetated Strip S. Stabill- Safi,: NI axp... d and man-..,*.d ,all shall be tabill—al by u.e of BMP',. This can Indude lemparary 6' high by 12' wide Compost Banns t the edge of dieturbonc., vUap (CI 2,) and/or hydraaeed (e120). BMP C120: Temporary and Permanent Seeding BMP C121: Mulching Other BMP', to be considered during con strvctian ae applicable BMP Cl 24. Sodding BMP C125: Tapsaning / Compa.ting BMP C126: Palyawytomide (PAM) far San Era.lon Protection BMP C130: Surface Roughening BMP C131: Gradient Terrace. BMP C140: Dust C.ntrd 6. Protect Slopes: Any temporary cvt and flll slope. need to be protected from eraelw nova and concentrated flow. unM permanent save and drainage -,a— ayetame are In Place. Plastic eh,,tIng ar mate (C123) are to be used as nxeasay prior to hyd-e-dbng and planting. BMP C123: Pl..U. Cowling 01her BMP', to be cansldered during can,tm,tlon as applicable BMP C120: Temporary and Permanent Seeding BMP C121: Mulching BMP C122: Net. and Blanket. BMP C124: Sodding BMP C730: Surface Roughening BMP C131: Gradient Terraces BMP C200: Interceptor ON. and Swale BMP C201: Grae,-Lined Channels BMP C203: Water Bare BMP C204: Pipe Slope Dralns BMP C205: Subsurface Oran. BMP C206: Level Spreader BMP C207: Check Dame BMP C208: Triangular Sill ON, (TSO) 7. Protect Drain Inlets: Catch basns downstream should have silt ...k. per COE ER-902 Installed or as additionally required by the city. BMP C220: Intel Protection o. Protect ail storm draln Inlets made operable during In.".Uan sa that tart ,ts, ru oft does not enter the nveya.nce eystsrn without first being filtered or treated to re.maw, aedk M. b. "" or rermaw and replace Inlet protect],, deAres when sediment has Filed one-third of the awllabl, .tarag. (unless a different at an dard Is specified by the product manufacturer). S. St.1,11ca Channels and Outlet.: Temporary and permanent ve yenta systems shall be etabit zed to prevent a aslon during and after constructlon. No channel, a —Uale from. the site a e prop... d. Infiltration I. the primary mean, of dispersing flows. r 01he BMPb to be considered during construction If applicable BMP C122: Net. and Blanket. BMP C202: Rlprop Channel Lining The beat ethod far .(01hing channel, 1. lac plat ly line the channel with BMP C122: Net. and Blanket. first, then add BMP C27: Check Dame a nes et .cry to function as an an char and tolawlaw the law of water, SWPPP NOTES CONT. 9. Control Pollutants: The plan far all pdlulonte' including waste ma tei,l, and demolition debris, I, that they wll be --d from site and property dlsp...d of. This Includes propar matnt... nc. of co t—tion equipment, and application a1 fertilizers. There Is no proposed application of clremlcols, or use of .oter treatment system.. BMP CI5i: Concrete Handling BMP C152: Sowcutting and Surfacing Pa11utlan Prawn U,n BMP CI53: Material D.Itvey, Storage, and Cantonment BMP C154: Concrete W.ehoul Area BMP C250: Construction Sto te, Chemical Treatment BMP C251: Construction Slormwoter Filtration BMP C252: Treating and Disposing of High pH Water BMP S419: Mobile Fueling of Vehides 10. Control De Watering: No dewateing le prop... d. If this became. n.ce..cry the water from de-wateting ea ]ems for any trencln ea, or foundations shall be di.charged into controlled .system. ea,. foundation, cult, and trench dewoter ng water, which hove similar clnaracl,ri,lk' to tormwot,r runoff of the site, Into a controlled conwyonce system before dls charge to BMP C240: Sediment Trap or BMP C241: Sediment Pond (Temporary). b. Discharge clean, non turbid dewaleing water, such as well -paint ground water, to systems tributary to, or directly Into surface water, of the Stale, as specified In Element 8: Stabilize Channel. and Outlets, ,...ideal the dewatering flaw doe. not ,eion a. fl,oding of receiving water.. Do of out. dean d ewe lering water through et—w.t.r sediment SM Pa. Note that '.u,f.— ter. of the Stale• may exlet on a con'tru atl.n its as well as off its; fare mple, a esk ru.ing nnthrough a It.. c. Handle highly turbid or oth—l- contaminated d—tc ing .ter separately from atarm water, d. Other dewate,ng treatment or di.p... I aptl-. may Include: I. inntmIlan' 11. Transport off site In a vehicle, such as a wcvum flush truck, fw legal disposal In , manner that doe. not puliute .tale waters. Ill. Ec �y-,pp. .d an ndaif, heml-I treatment or other Iv. gf— Son llory or combl—dl , discharge with local e,ww district approw1, If there Is ee no other optian. Use of a .dIm.nt.tion bag that dlachargee to a ditch or ,wale for small alum- of I —a fzed dewalering. If D... taring became. net awry the following BMP. should be con.ld...d. BMP C203: Water Bare BMP C236: Vegetative Filtration 11, Maintain BMP,: The Inspection and maintenance of the planned and Installed cons Uucllon BMP. shall be done a. required after any mea.urabie ,In av nts. Spare all fence shall be kept on ells along with applicable In.taMatt— con.tructbn equipment. NI BMP, .hall be removed at the end of the praject and property disposed of. BMP C15O: Material. ,n Hand BMP C160: Certlfled Ercelon and Sediment Control Lead -The site is under 1 acre so this to not required but should be c=dl... d If—11.1ble. 12. Manage the Project. -The all, shall be managed for ea'ion antra al all times. One f the most Important element, In the a genent of the project Is planning far contingencies based Ine risk of exposure during phases of the development It 1, 11 thUal that planning Is ongoing throughout the life of the prokcL The project anoge must eure that the project Is bunt n du h a ay to c ply w71h II Con.Uuctfan SWPPP E.m ante, a etailed In this sect'- Considerations far the project manage® Include, but are not Ilmited to: • construction phasing • ....anal work Itmltatia.n. • caordlnotlon with utiitie. and other cost... tar. • Inspection m-Itodrg • maintaining an updated construction SWPPP BMP', to be u.ed or.: BMP C150: Material. an Hand BMP C162 Scheduling Not required fw this project but should be considered If awls able. BMP CISO: Certlfled Erosion and Sediment Control Lead 13. Protect On -site Stormwater Management BMP, from roof, and olhs, hard au rfaces. C102 Buffer Zones and C103 High Naiblllty Plastic ar Metal Fence (C1D3) ... to be used to minimize disturbance n Downspout Infiltration or Oriwwoy/Walkwoy (Inflit-Uon) areas. Suggested BMP. fw Element 13 ... to be used to minlmlze disturbance in Downspout Infiltration or Drivesay/W.1kwoy (InfItratlan) areas BMP C1G2: Buffer Zones BMP C103: High -Visibility Fence as specified at it, boundaries: BMP C233: Sit Fence Not Required but should be considered If site conditions change BMP C200: Interceptor Dike and Swale BMP C201: Gra..-Lined Channel. BMP C207: Check Dome BMP C208: Triangular Sit M. (TSD) BMP C231: Brush Border BMP C234: Vegetated Strip APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: \ t4N "'•� Rig ti,•N` e�. p:3 '^ V O C iE 10 N U O 03 E� — W C 0 O GO �`S 5E O S O V) Call 48 Hours Before You Dig 1-800-424-5555 or 8-1-1 CITY ENGINEERING DIVISION A PORTION OF THE S.W. 1/4 OF THE S.E. 1/4 OF SECTION 24, TOWNSHIP 27 NORTH, RANCE 03 EAST, IN SNOHOMISH COUNTY, WASHINCTON 20/195 UNDISTURBED PARS UNDISTURBED TURF (LAWN) (SEE NOTE 1) AREAS (SEE`` NOTE 1) IItI I,I�IINI IIJ71 111 it UNSTURBED DI UNDISTURBED NATIVE V<GETATION j ro r� ' f !'. 0 11 !!!!!!I 1111 1 j 'f 1 TURF/IAVRI/LN}DSCAPE UNDISTURBED NATIVE SOIL ! !� L i�r r /j UNDISTURBED NATIVE SUL r F_�h✓� Sri �rI T �� ' l'^� 9 SLOPE MOTE - AMENDED SOBS SHOULD NOT BE 0P110N 1 - NO DISTURBANCE INSTALLED ON FINISHED SLOPES EXCEEDING 33X. AREAS EXCEEDING 339 SHALL BE STABILIZED PER THE PLANTING BEDS TURF (LAWN) AREAS ENGINEER/GEOTECH OF RECORD. z' ORGANIC MULCH I i /ice/ice/ a _.....g,t1t.=S..x`rl'+f'I':Iil IGwss: SEE, oR Soo 3' OF COMPOST 1.75' OF COMPOST INCORPORATED INCORPORATED INTO 5' OF - 117T0 6.25' OF SITE SOIL (TOTAL SITE SOIL (TOTAL AMENDED AMENDED DEPTH OF 9.5% FOR A DEPTH OF 9.5', FOR A _ SETTLED DEPTH OF B� SETTLED DEPTH OF 8-) 8 SUBSOIL SCARIFIED 4' BELOYI rl"St �J f 11Lr'Y R "\`I1� SUBSOIL SCARIFIED 4' BELOW COMPOST AMENDED LAYER GQMPOST AMENDED DYERS (12' BELOW SD1L SURFACE) F\�f (12 BELOW SOIL SURFACE) OPTION 2 - AMEND IN PLACE OR STOCKPILE AND AMEND GENERAL NOTES: LVNP PNG BEDS TURF (LAWN) AREAS 2' ORGANIC/��/J�J/f/' tf l )>, IIII I I I III) O I II (�l )� �I II�( 1. AREAS OF NO DISTURBANCE 'HILL BEAND EXISTING GRASS: SEED 1'EGETAlIONF AND E SOIL SHALL BE MULCH ��/��/� D• } ,I.. il,l OR SCO PROTECTED FROM CONSTRUCTION IMPACTS. 6' IMPORTED -I-- - 2. TO MEASURE SETTLED DEPTH, 6' IMPORTED WATER SOIL SUFFICIENTLY TO TOPSOIL MIX (COMPACTED TOPSOIL MIX FULLY SATURATE 1WTHour (COMPACTED CAUSING EROSION" DEPTH) 6• DEPTH) 3. COMPOST SHALL MEET SPEC. SUBSOIL IS i y) J> rx� / ? /l REQUIREMENTS THE 2017 ADDENDS S(CHECKTER SUBSOIL sCAR.IFIEO 0 � r% / i IS ADDENDUM (CHECKLIST 7), ED 6- IMPORTED�� yY,klt N `�{jY,n/�rRIMPORTED DELON 4. COMPACTION OF TOPSOIL (WHERE TO,NIX / < / r / �: REQUIRED) TO BE TO &SK (MAX)12• TOPSOIL MIX OF THE MAXIMUM DRY DENSITY OPTION 3 - IMPORT TOPSOIL PER MODIFIED PROCTOR TEST (ASTM D1557). -\ -_ POST CONSTRUCTION SOIL REVISION GATE APRR 2021 CITY OF EDMONDS DUALITY AND DEPTH STANDARD PUBLIC WORKS „ DEPARTMENT DETAIL SD-642 APPROVED BY: R. ENGUSH R -1/Y 2' MINIMUM SAWCUT SEE NOTE 10 MINUS CSTC- 1B' STAN44R0 \-e' CSTC OR CSBC PER WISDOT SEE ROTE 11� STD SPEC B-0.7.B(3) SEE HOTS 13 STANDARD TYPE A' CURB/GUTTER NOTES:a (NOT TO SCAM 1. CITY INSPECTION REQUIRED ON FORM WORK PRIOR TO POUR. 2. FORMS SHALL BE TRUE TO UN£ AND GRADE AND SECURELY STAKED. 3. FULL DEPTH EXPANSION JOINTS SHALL BE PLACED A)DIACEHI TO ANY STRUCTURE 4. FULL DEPTH EXPANSION JOINTS SHALL BE PLACED EVERY 10 FEET. 5. FULL DEPTH EXPANSION JOINTS SHALL HAVE 1/2' WIDE PR04 DM JOINT FTU.M. B. CONCRETE SHAM BE MASS 3000/GOMMERCML MIX. 7. FINISH SHALL BE LIGHT BROOM. B. CURB AND GUTTER SHALL BE SPRAYED WTH CLEAR CURING COMPOUND OR SHAM BE COVERED AND KEPT MOIST MR 72 HOURS. B. REM(AAL/IRRACTr OF CONCRETE CURB SHALL BE FROM EXPANSION JDHT TO EXPANSION JOINT, UNLESS OTHERWI E DRECTAD BY CITY ENIMNEER. 10. A 2-F7 MINIMUM ASPHALT SAWCUT MAY BE REWIRED WHEN EXISTING PAYMENT WOULD ABUT NEW CURB/GUTTER 11. CLAZB/OUrDR SHALL BE 18' OR AS DIRECTED BY CITY ENGINEER. RUM TO CITY STANDARD CONCRETE CURB AND CUTLER DETAIL TR-520. 12. F1 4L JINNI SHALL BE A NEAT SUM CUT STRAIGHT UNE ALL EXPOSED VERTM.LL EDGES SHALL BE TACKED NEATLY PER WSDOr STANDARD SPECIFICATION 5-04.3(4) APPROVED TACK OR APPROVED EQUAL AND SEALED PER WSOOT S E, 5-04.3(4)A 13. CSTC SHALL BE INSTALLED UNDER HM WHEN HIM SAWCUT IS REQUIRED, CSBC SHALL BE INSTALLED UNDER HIM LL WHEN FUROAD RECONSRNCDON B REQUIRED. 14. NATIVE AND GRAVEL SUBCRADE SHALL BE COUPACTED TO A MINMUM OF 95X LUX DENSELY. CITY OF EDMONDS VERTICAL CONCRETE CURB DA RAPRILN2021E STANDARD PUBLIC WORKS AND GUTTER - DEPARTMENT FSI, ,aK1° DETAIL TR-520 APPROVED BY: R. fNOUSN rOGNTTIDUR LINE MGUE TERMINAL EN UPHILL 24" TO 48' .4 PREVENT FLOW TRENCH, SEE NOTE 2STAGG a' MIN 4' MAX rc, a t sF' F 2* MIN GIVOILAPS WDDDEN STAKE W DAM �yua a�•'A �/ I a.MIN WATTLEIa, SMIT TRAPPING UE WATTLE SPACING TABLE (TYP) AREA AYAJLAHLE FOR SPACING VARIES SPACING TABLE SLOPE MAXIMUM SPACING WATTLE _ SECTION ®� ,. el INSTALLATION •AT LAIR 4,. a•a. NOTES- 1. COMPOST WATTLES RECOMMENDED ON SLOPES USE STRAN WATTLES IN PAYMENT APPUCATDN, 2. ON SLOPES, INSTALL WATTLES PERPENDICUILR TO THE FLOW D;RECIION AND PARALLEL TO THE SLOPE CONTOURS. INSTALLATION SHAM BE IN ACCORDANCE WITH III STANDARD SPECIFICATION 3. RUNOFF SHALL NOT RUN UNDER OR AROUND ROLL. ADDITIONAL STAKING WY FIE NECESSARY TO PREVENT UNDERCUTTING. 4. WATIL S SOULL BE RRSPECIED RMAULARLY, AND IMMEDIATELY AFTER A RAI'.WALL PRODUCES RUNOFF, REMOVE SEDIMENT AND ACCUMULATIONS WHEN EXCEEDNG 1/2 HEIGHT BETWEEN THE TOP OF THE WATTLE AND THE GROUND SURFACE �,- REMON DATE CITY OF EDMONDS JAKUAR 251e WATTLE INSTALLATION PUBLIC WORKS STANDARD - DEPARTMENT DETAIL 19y° I APPROVED BY: R. DICILM ER-903 -FULL DMTH EXPAN ION JOINTS I EXPANSION JOINT 4 z SEE DRIVEWAY Z4• II S (Z \ DRNLIVAY APPROACH -1) \�/ 1 CONCRETE CURB AND DIFFER, SEE COE SID OTL 6• 7YP \ TR-520 EXISTING PAVEMENT 2' MIN FULL DET'TH MAX 15 1/2' EXPANSION SAW` u T u4K 6' CURB 3 2 SECTION A -A DRIVEWAY CURB TRANSf1TONAL DETAIL FOR .ORB AND G ❑'TOR OR VFRR AI CURBS NOTES: ( CURB IOR oD POUMMt SHALL BE POURED SEPARATELY FROM THE SIDEWALK. CITY INSPECTION REWIRED ON FORM WORK O DRIVEWAY APRON INCLUDING WING RAMPS SHALL BE A MINIMUM OF 6' THKK AND SHALL BE PLACED ON 2' OF 5/8' CSTC COMPACTED TO 95X MAXIMUM DENSITY. O SUBGRADE SHALL BE COMPACTED TO 95K MAXIMUM DENSTY. O 2' ASPHALT SAWCUT REQUIRED WITH CURB/CURER INSTALLATION. BETTER TO WE STD OTL TR-520, O CONCRETE SHALL BE CLASS 3000. ©CURB TRANSITION SHOULD MAINTAIN A SLOPE NO GREATER THAN 8.3%. IF THE SLOPE REQUIREMENT CANNOT BE ACHIEVED, MAXIMUM CURB TRANSITION LENGTH SEWN BE 15-FEET. �] MANTAIN 1/2' UP AT GLITTER. &F DRIVEWAY WIDTH EXCEEDS IS'. INSTALL A FULL DEPTH EXPANSION JOINT AT CENTER OF DRNEWAY. @ INSTALL MINIMUM 5-FT TRANSITION PANE. BETWEEN DRIVEWAYS AND WHEN CONNECTING TO EXISTING SIDEWALK. HI FINISH SHALL BE UGM BROOM. CITY OF EDMONDS DRIVEWAY APPROACH RAAPPRIOLN20211 TYPE I PUBLIC WORKS STANDARD DEPARTMENT DETAIL f I Ig9° APPROVED BY: R. ENGUSH TR-SAIL i "�25' MRN -us oo H ) \ QUARRY SPALLS 2-4' MIN DW 12' MIN DEPTH 18-EPT14 IF INSTALLED OVERINFILTRATiON .i TRENCH LOCATION PRGAGE FULL WIDTH OF INGRESS/EGRESS DETAIL NOTES: O THE MINIMUM LENGTH SHALL BE EXTENDED AS NECESSARY TO ENSURE MATERIAL IS NOT TRACKED OFF SITE AND/OR INTO THE PUBLIC RIGHT-OF-WAY. O ATB DRIVEWAY RAMP AND/OR SITE ACCESS ROAD 15' WIDE MIN. SEE TABLE BELOW FOR REQUIRED LENGTH. NOTES: 1. SURFACE WATER - ALL SURFACE WATER ROWING OR DIVERTED TOWARD CONSTRUCTION ENTRANCES SHALL BE PIPED ACROSS THE ENTRANCE IF PIPING IS IMPRACTICAL, A MOUNTABLE BERM WITH 5:1 SLOPES WILL BE PERMITTED. 2. MAINTENANCE -THE ENTRANCE SHALL BE MAINTAINED IN A CONDITION WHICH WILL PREVENT TRACKING OR FLOWING OF SEDIMENT OFF SITE AND/OR ONTO PUBLIC RIGM-OF-WAY. THIS MAY REWIRE PERIODIC TOP DRESSING WITH ADDITIONAL QUARRY SPALLS AS CONDITIONS DEMAND AND REPAIR AND/OR CLEANOUr OF ANY MEASURES USED TO TRAP SEDIMENT. ALL SEDIMENT SPILLED, DROPPED, WASHED DR TRACKED OFF SITE AND/OR ONTO PUBLIC RIGHT-OF-WAY MUST BE REMOVED IMMEDIATELY. 3. WHEELS SRALL BE CLEANED TO REMOVE SEDIMENT PRIOR TO LEAVING THE SITE. WHEN WASHING IS USED, IT SHALL BE DONE ON AN AREA STABILIZED WITH QUARRY SPALLS AND WHKH DRAINS INTO AN APPROVED SEGMENT TRAPPING DEVICE 4. INSPECTION AND NEEDED MAINTENANCE SHAH BE PROVIDED AFTER EACH RAIN. M •PRONOE AT B OR ASPHALT •PRONOE AT B OR ASPHALT TRANSD ON WHERE FRONTAGE ROAD IS AN ARTERIAL LENGTH TO BE DETERMINED BY Cm INSPECTOR. CITY INSPECTION REQUIRED ON ALL EROSION CONTROL METHODS BEFORE OTHER WORK CAN BEGIN _ REVISION 0.47E CITY OF EDMONDS STABILIZED CONSTRUCTION JANUARY 2018 ENTRANCE PUBLIC WORKS STANDARD DEPARTMENT DETAIL 4', T$9° APPROVED BY: R. ENGUSH ER-901 Call 48 Hours Before You Dig 1-800-424-5555 or 8-1-1 APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: I u�L U) 7 O LO O A C O C S_ N N � a 0 E� lo C W 0 O (� TL U F L 0 I BY: CITY ENGINEERING DIVISION A PORTION OF THE S.W. 1/4 OF THE S.E. 1/4 OF SECTION 24, TOWNSHIP 27 NORTH, RANGE 03 EAST, IN SNOHOMISH COUNTY, WASHINGTON 21/195 SEE APPLICABLE STANDARD DETALS ERMME AND GRATE PIPE ALLOWANCES _ PIPE MATERIAL MAXIMUM INSIDE DIAMETER RENHFERCED OR 12' PION CONCRETE ALL METAL PIPE 15' CPSSP 12' (WSOOT STD SPEC 9-05.20) SOLED WALL PVC is' (WSOOT SID SPEC 9-05.12,(1)) PROFILE WALL PVC 15' (WSOOT STII SPEC 9-05,12{2)) ti \ S• 3 1L • POLYETHYLENE 5• g I� STUCORRUGATED STORM SEWER PIPE 6', OR 12' RISER SECTION 1 CATCH BASIN$ SHALL BE CONSTRUCTED 04 ACCORDANCE WITH WSOOT STANDARD SPECIFICATION 9-05.50(3). 2. AS AN ACCEPTABLE ALTERNATIVE TO REBAR, WELDED WIRE FABRIC HAVING A MITI, AREA OF 0.12 SQUARE INCHES PER FOOT WAY BE USED. WELDED WERE FABRIC SHALL COMPLY TO ASTM A497 (NCKO N 221). WWNE FABRIC SNW1 NOT *'Viy BE RILED W KNOCKOUTS. xtYl S. APPLY NON -SHRUNK GROUT TO WSEDE AND OUTSIDE OF I( �` ALL J02RS, RINGS, R-SERS AND FRAMES. \ 4. ROUND KNOCKOUTS MAY BE ON ALL 4 SIDES, WITH MAX / DIAMETER OF 20', KNOCKOUTS MAY BE UTHFR ROUND OR '0' SHAPE. 5. THE MAX DEPTH FROM THE 1TN15HfD GRACE TO 711E PIPE INVERT IS 5'-0'. 6. THE TAPER ON THE SUES OF THE PRECAST BASE SECTION AND RISER SECTION SHALL NOT EXCEED 1/2-/FT. 7. CATCH IEISW FRAME AND GRATE SHALL HE Pi ACCORDANCE WDH STANDARD SPECIFICATIONS. MATWO SURFACES SHALL BE FINISHED 10 ASSURE NON-RDCKING FIT WITH ANY COVER POSITION. (MEASUREMENT AT THE TDP OF THE BASE) PRECAST BASE SECTION 6. VERTICAL EDGE Of RISER SHALL NOT BE MORE THAN 2' FROM VERTICAL EDGE OF CATCH BASIN WALL Y OF EDMONDS CATCH BASIN TYPE I REVISION DATE JANUARY 2013 PUBLIC WORKS STANDARD DEPARTMENT DETAIL SD-303 APPROVED BY: R. EROUSH MECHANICAL PL1TG DWTTC RATED, CIRCULAR DOCKING EXTEND CLEANOUT 2' ABOVE DESIGN PONIXNG ELEVATION ASPHALT/ CAST VALE BOX PER MANUFACTURER OR PER PLAN CONCRETE \ \1 RECOMMENDATIONS, SEE NOTES 1 AND 2 4' STREAMBW COBBLES _--�- - PER WSOOT 9-03.11(2) DESIGN PONIXNG ELEVATION I LT 1F Ii T�UHI� i Ii 1 MECHANICAL PLUG Ij � II 11F 11J ;:-} TII )I'--1 II]. 31 ADD VALVE Box EXTENSION DR S01L 7 IT �I� IT {If,TII 11 PIPE AS NECESSARY PIPE j TO ALcouuoGTE O.D. OF RISER PIPE t1,�I)I (I�IN }� SOIL Taff 4s DENDI } CLEANOLT COVER IN MEW Wr SOURER TI�ITT 3O I� LAWN/ NOO SERIES VALVE LANDSCAPESOSH LOCKING ty 'c k}I.✓ +` }}*i.S UNDEIiLARS PIPE 1Jv�T>:L 1[ PER PLANS � OR EQUAL SEE 1 AND 2. y'1. ,lnfrrfPLUG OR CONRINUED UNDERDRAIR CRVSHEO SURFACN7GCDNNECTION IICAL PLUS TOP COURSE (csrC)CLEANOUT PER WSOOT 9-03.9(3 (SW" WITHIN SMETERnoN FAc'" CLEANOUT COVER IN GENERAL NOTES: LANDSCAPE AREA 1. CLEANOUT PIPE $HALL BE SAME SIZE AND MATERIAL AS UNDERDR/JN PIPE 2. CLEA40UT SHALL BE INSTALLED TO ALLOW FOR MAINTENANCE ACCESS TO ALL PIPES. 3. ALL FITTINGS SHALL BE SOIL TICI4T. 4. CLENNOUT RISER TOP SHALL BE LOCATED OUTSIDE OF PONDINO AREAS WHERE POSSIBLE. NOTES: 1. CLFANOUT COVER TO BE LOCKING WITH ALLEN HEAD BOLT, MARKED 'GRAIN CLEMEOUT,' 'CLEANOUT,' 'CD,' OR SIMILAR, 2. TRAFFIC RATED LID REWIRED IN AREAS WITH VEHICULAR LEADING. STORM DRAINAGE REVISMN DATE CITY OF EDMONDS CLEANOUT DECEMBER 2017 STANDARD PUBLIC WORKS DEPARTMENT DETAIL FB J. 1000 SD-61 9 APPROVED BY: R. EMOUSH TYPE i OR 1-L GTCH _ LINT BRAN FIFE 1 > BASH W/ SOLED DD PER C'JTTEt -�- .� CRY STANOMD DETAIL [� 50-303 OR SD-304 i. 5 IVFILTRADCI TOENCH-� ...F .A EXTEU. LIi FERTY LIIIE/EASEVEINT A' (NEC) CIA- DBSERYATION AELL5 S PALED 25' APART (!OAK). . 5511� (MINT PER TRENCH PI AN OATS f 6 NDUT (TAN) PEFGNNSNETT Fw UlI.1U DRN.i PFE PER 'A�CMJT SPEC, 9-052(6), UID LE•EL 38• I Do, (MAN PH PLASTIC Box VARY.FD 'GRAN' i-TEST PANG oasE'ramzr, 1141E 'T` ND7E 3 WASHED D- I ROCK, SEE NOTE 2 GEE NUTNE SEE NOTE 1 UNC ItAL, W NA7 NEJ MATERIAL, SGAIiY 3' - (MIN) SECTION OATS DEPARTM BUILDING •• TFF 6' M74 4' (MI") WC DRAIN ( ) PF'E rEa WSWT LE1Ft 5'Ef, 9 05.10) �} 12' (TAN) VWNT^I'• I)SID,E SLOPE REVOVP3LE PUSH DM1 Pl�C TEE P.'C Dwcl PL-£ GFNFRAI NOTFS: I. REFER TO Tiff 2017 CITY OF EDMONDS STORMWATER AD Dc7Dvm FOR SETBACK (CHECKLIST13) AND PNFEASEpD1Y REQUIREMENTS. R`.rR :TE➢ .A.CKFLL 2 WN COVER DEPTHS ASSUME NO VETNICUTAR LOADING. DESIGNER TO SPECIFY COVER DEPTHS IF WHO" TRAFFIC A"CPATED. NOTES: - 1. RACE 110111(TRE FABRIC ALONG WALLS AND TOP OF WASHED ROCK. CEOTEXILE SHALL CONFORM TO 315'1, (41H) SSEEPARATION. N0N-AUT SPEC. VEU TYPE. FOR AIKYIE %G NFL 2. WASHED DRAIN ROCK 91ALL CWFORU TO WSOOT HN H SPEC. 9-03, 12(5), GRAVEL BACKFLL FOR OVOELL.S. GROUND'VIATER TABLE OR 3. OBSERVATION WELL SHALL Ca"FORM TO WSDOT H1'DRA.IDJLLY SPEC. 9-05.2(6). PERFORATED PRO UNDEFDRAH REST-11CINE PIPE LAYER REVISION DATE )AIDS TYPICAL DOWNSPOUT APRIL 2021 INFILTRATION TRENCH ;S STANDARD DETAIL APPROVED BY: R. ENGLISH SD-636 7 g :CE FIIUL JOINT SHALL BE A NEAT SAW OUT STRA}CHI DIVE ALL IXP0BED VERTICAL HMA CLASS 1/2' GLEANGUT WITH 45' EDGES SHALL BE TACKED NEATLY PERPG 58H-22 WSOOT STANDARD SPECIFICATIONS 5-D4.1(4) (SEE NOTES 4 k 5) BEND AND CAR -- i I APPROVED EALED D TACK OTT SIB 504D. EQUAL AND 1 C(MAX) SLOPE EXCAVATION TO AVOID UNDERMINING SEE COE STD DR GU-410 \ I EXISTING PAVEMENT. NOT TO D(CEED 100' BETWEEN CLDNOUTS CLEANOUT (ANT WITH CAP ARID CLEANOUT COVER) AND / / //// //// EXNSII.NC CONCRETE LEVELNG COLLAR o // HMA COVER///,EE E.� / NOTE 312'} FINISHED GRADE D OF PIPER GRIPPER RUG HERNE 27061 OR APPROVED ;g4EQUAL) /,// / / / /// // / / BEDDING VAIEAlA1LNEAG (1-1/4' MINUS) 6' MINN BASE COURSE \��\� \�N \��° d �."; °4 EXISTINNG \ , MATERIAL WATER TIGHT CAP // // �/ /� ,/ // // (SEES NOTES2 BELOW a a //// RISER LEVELING COLLAR �` SEE NOTE 4 // / / / / BEDDING WTERIPL (1-1/4- MINUS) CRUSHED SURFACE BASE COURSE 45` , // // (SEE NOTE 3) ! 12' PVC SLEEVE \�s, // // \Y- 6' RISER a // // // 4' OR 6' SIDE SEWER 6' MIN / / / / / / / // / / / / / , , FOUNDATION (IF REQUIRED) TOIMPORT95BMADIMU SHALL BE COMPACTED I) UM DENSITY 8' WYE AND B' CITY STUB :EN AI FAMQ R DEfAi 45 BEND SEE NOTE 4 (SEE NOTE 8' MIN - B' MIN TRENCH W10TH 4' OR 6' 12 LOCKING COVER SIDE SEWER CLEANOUT DETAIL SEE NOTE 1 NOTES: SEE NOTE 3 AT PROPERTY LINE CRY EASEMENT 1. SEE CRY OF EDMONDS MDDIFlCATIDNS TO DIVISION 9 OF THE CURRENT MOOT STANDARD SPECIFMATIDNS FOR LEVELING COLLAR NOTES: UIREM BACKFl WNC REQUIREMENTS. Z o >> a SEE NOTE 4 a s G ASPHALT SURFACE 1. SEWER PPE S1LAL1 BE SDR-35 AND JOINTS SHALL BE NOTES: 2.. SUBMIT PROCTOR M40OF DENSITY TESTS FROM CERTIFIED TESTING COMPANIES DOCUMONTINC THAT THE BAC.KFlLL CA.SM.ETED MEETS A MINIMUM OF 95% DE1i51tt PER ASTId D 1557. - 12'f 2, PIPE SLOPE TO BE 2S MIN AND UP TO 501E MAX. 1. MAXIMUM WTOTH OF TRENCH AT TOP OF PIPE • 16' OR LESS FOR 6' .0 SMALLER DIAMETER PIPE 3. CSBC DEPTH SHALL BE A MINIMUM OF 6'. AND SHALL BE 114STALLED IN MULTIPLE EQUAL THICKNESS LIFTS NOT EXCEEDING 6'. 3. SEWER LEAROUT COVER TO BE EAST JOREW INCH WORKS 24' FOR B' DIAMETER PIPE 1 FOOT LONG 12- PVC PRODUCT /00386102 OR APPROVED EOLAL 36' FOR 12' DIAMETER PIPE 4. ROADWAY HMA DEPTH SHALL BE A MINIMUM OF 4' FOR RESIDENTIAL ROADS M40 6' FOR COLLECTORS/ARTERALS. SLEEVE O.D. PLUS 18' FOR PIPE LARGER THAN 12' NOMINAL DIAMETER 6' RISER 4. LEVELING COLLAR Si{V1 BE CONSTRUCTED AS FOLLOWS: END OF PIPE GRIPPER 2. REFER TO DMSIEN 9 OF WSOOT STM40MD SPECIFIGTO NS FOR MATERIAL GRADATION AND ADDITIONAL INFORMATION. 5. ALLEY HMA DEPTH SHALL BE A MINIMUM OF 2' THICK. UNLESS APPROVED BY THE ENGINEER, ANY DEPTH GREATER THAN 2' SHALL MATCH EXISTING. PLUG(CNERNE 270261 • IN ROADWAYS PER COE STD DWG GU-424 OR APPROVED EQUAL) 3. TRENCH BACKFlLL SHAH MEET A MINIMUM COMPACTION OF 95% DENSITY PER ASTM 0 1557. 6. UNLESS APPROVED BY THE ENGINEER. THE HMA SRN1 BE INSTALLED IN MULTIPLE EQUAL THICKNESS LIFTS NOT 24'X24't6' • IN P CONCRETE COLLAR AREAS, EITHDIAMETER TYPICAL CLEANOUT DEEP CONCRETE COLLAR OR 24' DIAMETER X 6' DEEP 4.IF UNSTABLE MATERIAL IS ENCOUNTERED BELOW PIPE ZONE, CONTRACTOR SHA1 REMOVE AND REPLACE AS REWIRED EXCEL PKI 2'. CONCRETE COLLAR BY CITY ENGINEER. 7. FINAL P JOINTS SHALL BE NEATLY SAW CUT AND SEAT_ WTRN WSOOT STANDARD UNDER ASPHALT OR CONCRETE SPECIFICATIONS 5-04.3(4)A APPROVED JOINR SEALANT DR APPROVED EQUAL CATIONS ED JOINT APPROEDV) yr CITY OF EDMONDS SEWER CLEANOUT DETAILS REVES N DATE FEBRUARY 2022 ^ CITY OF EDMONDS TYPICAL TRENCH SECTION REVISION DATE APRIL 2021 CITY OF EDMONDS TYPICAL HMA AND UTILITY PATCH REVISION DATE AP RIL 2021 STANDARD STANDARD STANDARD PUBLIC WORKS PUBLIC WORKS PUBLIC WORKS DEPARTMENT DETAIL _' ----- DEPARTMENT DETAIL -----=�- DEPARTMENT DETAIL Fs! jg9O SS-200 _ FsN -1880 GU-400 fsl, 18AO GU-410 APPROVED BY: R. ENGLISH APPROVED BY: R. EHGUSH APPROVED BY: R. ENGUSH In z O 1n U) C O O � 0 B N C : 0 N ET O r W O W 0 U � � S O R U _° 0 J) V Call 48 Hours Before You Dig 1-800-424-5555 or 8-1-1 APPROVED FOR CONSTRUCTION CITY OF EDMONDS DRAYS JCO/ DESIGNED: RDH DATE: APPROVED: RDH DATE: a/12/: BY: PROJECT N0.22- CITY ENGINEERING DIVISION SCALE: N-A SHEET OF A PORTION OF THE S.W. 1/4 OF THE S.E. 1/4 OF SECTION 24, TOWNSHIP 27 NORTH, RANGE 03 EAST, IN SNOHOMISH COUNTY, WASHINGTON 22/195 i54 Fencing or Chain 4' In Height Block 095FFVATGN PIPE N.ViKING E I OR I-L CATCH CENTER OF OItfWELL BASIN W/ SOLID LID PER As-U. (MN) DRYWEIl CRT' STANDARD DUAL SO-303 OR SD-304 4' (NIN) PERFCRAIE0 F" UN GRAIN PIPE ' \ \ ("IN) P•JC - CLEANOUT f r,Ra4 PI,=E (TrP) 5 \ 5 (aN) � � 10' (✓IN) PnoPaerr u+s�£nsE+.�rr — — I PLAN Irts �W � I 4- (LAIN) PVC DRAM PPE PER WSOOT SPEC, 9-05.1(5), IS (INN) 9LCPE J. •. _ TEST PLUG N PLASTIC BOX VARI�D'DRNN' CLFA\OUFT 12' BUIDl`IC 12- (MN) f- a" (vIN) PVC DRAIN %PE PER TOPSOIL N WSDOT'PEC91}5.1(`.), POS IITJE ........ 6' (N4N) iLOPE GENERAL NOTES: 1z' (Len) rJ 4' (NIN) 1. REFER TO THE 2017 CITY Of 5 PERFORATED PW _FENOVABLE EDMONDS STORWNAIER ADDENDUM UNDERDRAiN FOR SETBACK (CHECKLIST 13) ANO PUSH- J.''. %PE PER WSDOT PVC TEE IN""E'aTIY REOUREMENIS. SPEC. 9-05.1(6) 2, NINWUN COVER DEPTHS ASSIWE NO GEOTE]TLE SEE NOTE I VEHICL A4 LOADING. DESIGNER TO SPECIFY COVER DE IHS IF WASHED MAN ROCK. VEF91U(AR TRAFFIC AND(2PATED. ]. PRONDE iO T1FT (WIN) SPACING SEE NOTE 2 —_ UNCCNPACTED IUTNE J BETWEEN GRY Y,4ll5. N S: MATERIA3, SCARIFY 3- 1. PLACE GEOTEMILE FABRIC ALONG WALLS AND TOP OF WASHED ()RH) V (INN) ABOVE SEASONAL ROCI(. GEDTE[i1LE SHALL CONFORIJ TO WSDOi SPEC. 9-33.2(1)• HGH GR0151ONATER TAPE GEOTEXIILE FOR SE'PARABON, BON—TYFE OR HYDRNUIUMLY RESTRICTIVE LAYER 2 N'ASIIED ORNN ROCK SHALL CONFORM TO WSDOT SPEC. 9-D3.12(5), GRAVEL BACKFL.L FOR DRYWEILS. PROFILE NTS 3. OBSERVATION WELL SFULL CONFORM TO WSDOT SPEC. 9-05.2(6), PERFORATED PVC UNDERDRAI4 PIPE. _ TYPICAL DOWNSPOUT REVISION DATE APRIL 2021 CITY OF EDMONDS INFILTRATION DRYWELL STANDARD r'-- PUBLIC WORKS _ DEPARTMENT DETAIL Fa(, �g9D SD-638 APPROJEO BY: R. MUSH 4- V) 4 O O OU O C L _ � � O N U O 03 O N -o E O o -a- In E' O -0 OCO) � S 0 O _ O 0 U 0 O ) Call 48 Hours Before You Dig 1-800-424-5555 or 8-1-1 APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION 23/195 Appendix: Area Topo Map, and SCS Map Ryner-Raman Category 1 Drainage Plan Page 15 24/195 I u, o• tall Wil t� '� o l 111Z1 a LZLIC 13.01 N `11501 10 f5U1 ' 7�01 16 4bo 1 f 91,01 urns .but GEC>t Zb0l ` Y>FO , I( < � V Vol ROW L70 11 11.1111 J '0 17 rCUI hZ01 I E 940l J tJ( {,l 61.01 W ICoI►' Dial Ozol Q 51(�I /101 3101 1 W r ;101 \ CIUI 6(h)I It'll 14 ki tool ' (•001 Illl I%h /CWL j 096 na (15G �� • 756 65G I rn Gib bIOil 6 11G I OS6 btrh r 'ti G 0,4 EG � CbG St _ 4F6 �--•� S .} \\ i �- \ N t'Z6 ILI -• � 616 a111 b ...._ ,. 0�• w '� 1 l G �� - � /.06 j `lIA• 1.16 -6_ _� Ig♦ L(1s .:mot 1 CbkJ ---- a Soil Map —Snohomish County Area, Washington 25/195 vt^ a � (Raman) � 5477M 54TI17 547744 W51 M7758 547M 647M 4 ,, 4"T 76, r, 4N 48' 2ti' N t. r , "T 14 r 1 ` e i 9t7 - 1 � Jj SP � •► h 1 r I a Ry,Aak "1'4li, :.1A Sail M'tt� nt,ry nm va'I1CLait this it 47' 48' 24' N FFFllllll 647M 547737 547744 5477': t 647758 3 a � Map Scale; 1; 276 f printed an A portrait (8.5" x 11")sheet. N 0 4 8 16 24�� A Feet 0 10 20 40 60 Kip projedlon: Web Mercator Caner coordinates: WGS84 Edge tics; UTM Zone 1ON WGS84 USDA Natural Resources Web Soil Survey Conservation Service National Cooperative Soil Survey tM y �•; it PO 47' W 24• N 547766 6em 3 7/20/2022 Page 1 of 3 Soil Map —Snohomish County Area, Washington 26�jpa� Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 17 Everett very gravelly sandy loam, 0 to 8 percent slopes 0.3 100.0% Totals for Area of Interest 0.3 100.0% USDA Natural Resources Web Soil Survey 7/20/2022 Conservation Service National Cooperative Soil Survey Page 3 of 3 MAP LEGEND Area of Interest (AOI) — Area of Interest (AD[) Soils Soil Map Unit Polygons . r Soil Map Unit Lines 13 Soil Map Unit Points Special Point Features V Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit ,. Gravelly Spot Landfill R Lava Flow Marsh or swamp s Mine or Quarry Miscellaneous Water Ion Perennial Water '�_r Rock Outcrop + Sal:ne Spot Sandy Spot —t Severely Eroded Spot 0 Sinkhole Slide or Slip Sodic Spot Soil Map--Snol ish County Area, Washington (Raman) MAP INFORMATION Spoil Area The soil surveys that comprise your AOI were mapped at 1:24,000_ � Stony Spot Very Stony Spot Waming: Soil Map may not be valid at this scale. wet Spot Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil Other line placement. The maps do not show the small areas of Soec al Line Features contrasting soils that could have been shown at a more detailed scale. Water Features Streams and Canals Please rely on the bar scale on each map sheet for map measurements. Transportation Rails Source of Map. Natural Resources Conservation Service Web Soil Survey URL: �.. Interstate Highways Coordinate System: Web Mercator (EPSG:3857) US Routes Maps from the Web Soil Survey are based on the Web Mercator Major Roads projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Local Roads Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. Background M Aerial Photography This product is generated from the USDA-NRCS certified data as of the version date(s;) listed below Soil Survey Area: Snohomish County Area, Washington Survey Area Data: Version 23, Aug 31. 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Sep 2, 2018—Sep 25, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. USDA Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/20/2022 Page 2 of 3 28/195 Appendix: Photographs Ryner-Rain an Category 1 Drainage Plan Page 16 29/195 North side of Walnut looking south at existing house and road frontage. North side of Walnut looking southeast at existing road frontage. Ryner-Raman Category 1 Drainage Plan Pictures Page 1 30/195 Waln<<t looking west. End of existing curb cut. Existing house, driveway carport and water meter. Ryner-Raman Category 1 Drainage Plan Pictures Pale 2 31/195 Existing house, shed and backyard. Ryner-Raman Category 1 Drainage Plan Pictures Page 3 32/195 Appendix: Infiltration Trench Design and VWVHM Output Ryner-Raman Category 1 Drainage Plan Page 17 L33/1 „,.CL,\f R c-, w\ C%. vN 'ww tin O&4( , ZtiC&V- � U`rt� cVV�2c� L, Al VA c�v�•— 5; Lam. Sq,S 5 � L) 1- !-A � ��► �V-j _ ►. Ova-R�Loc.� a �{ 1� -�-1 o k-e � ,w 3' 34/195 August 18, 2022 Page 6 of io Geotechnical Evaluation The backfill adjacent to and extending a lateral distance behind the walls at least 2 feet should consist of free -draining granular material. All free draining backfill should contain less than 3 percent fines (passing the U.S. Standard No. Zoo Sieve) based upon the fraction passing the U.S. Standard No. 4 Sieve with at least 30 percent of the material being retained on the U.S. Standard No. 4 Sieve. The primary purpose of the free -draining material is the reduction of hydrostatic pressure. Some potential for the moisture to contact the back face of the wall may exist, even with treatment, which may require that more extensive waterproofing be specified for walls, which require interior moisture sensitive finishes. We recommend that the backfill be compacted to at least 90 percent of the maximum dry density based on ASTM Test Method D1557. In place density tests should be performed to verify adequate compaction. Soil compactors place transient surcharges on the backfill. Consequently, only light hand operated equipment is recommended within 3 feet of walls so that excessive stress is not imposed on the walls. Storrnwater Management Feasibility The site is underlain by weathered and unweathered outwash. We performed a small scale pilot infiltration test (PIT) in TP-i. The test was performed in general accordance with the Washington State Department of Ecology stormwater manual. The area was excavated to a testing depth of approximately 4.0 feet below the ground surface. The design infiltration rate was determined by applying correction factors to the measured infiltration rate as prescribed in Volume III, Section 3.3.6 of the DOE. The measured rate must be reduced through appropriate correction factors for site variability (CFv), uncertainty of test method (CFT), and degree of influent control (CFM) to prevent siltation and bio-buildup. It should be noted that construction traffic or other disturbance to the target infiltration area could compact the soil, which may decrease the effective infiltration rates. The correction factors and resulting design infiltration rate are also shown in the table below. Test Test Measured Correction Factors Design Number Depth (ft) Infiltration Infiltration Rate (in/hr) Rate CFv CFT CF4r (in/hr) TP-i 4.0 4.2 0.6 0.5 0.9 1.134 Infiltration appears to be feasible in the underlying outwash with less than 7 percent fines. We recommend removal of any dense soils or silty -sand layers/pieces during system placement if encountered. We should be on site during construction to verify the soil conditions. We can provide additional recommendations upon request and once civil plans have been prepared. We should be provided with final plans for review to determine if the intent of our recommendations has been incorporated or if additional modifications are needed. (206) 331-1097 ICJI ill IF- 1 Date: August 2022 Depth: 8' Groundwater: None Contractor: Jim Elevation: Logged By: PH Checked By: SC o> o Moisture Content (%) 0 a 4 T O 3 Plastic I / I Liquid Limit Limit Q a N Material Descriptlon C o j o DCP Equivalent N-Value O 0 10 20 30 40 50 _____ ___ __ T_o_psoil/Vegetation_______________ 1 SM Loose to medium dense, silty -fine to medium grained sand trace gravel, reddish brown to yellowish brown, dry to moist. 2 (Weathered Advance Outwash) 3 ------ 4 --- -- SP --------------------------------------------- Medium dense to dense, fine to medium grained sand trace silt trace gravel, grayish brown, moist. (Advance Outwash) 5 6 Local caving 7 End of Test Pit 8' 9 10 Cobalt Geosciences, LLC Proposed Residence P.O. Box 82243 Test Pit Kenmore, WA 98028 COBALTI 1o5o Walnut Street Logs (2o6) 331-1097 '1 eo.com g ww%Nwobalt � Edmonds, Washington � wbaltgeo(r� em ail.com 36/195 WWHM2012 - 15 MINUTE TIMESTEPS RYNER-RAMAN RESIDENCE PROJECT REPORT Project Name: ryner-raman residence Site Name: Raman Residence Site Address: 1050 Walnut St City : Edmonds Report Date: 1/4/2024 MGS Regoin Puget East Data Start 1901/10/1 Data End : 2058/09/30 DOT Data Number: 03 Version Date: 2023/01/27 Version : 4.2.19 General Model Information WWHM2012 Project Name: ryner-raman residence Site Name: Raman Residence Site Address: 1050 Walnut St City: Edmonds Report Date: 1 /4/2024 MGS Region: Puget East Data Start: 1901/10/1 Data End: 2058/09/30 Timestep: 15 Minute DOT Data Number03 Version Date: 2023/01/27 Version: 4.2.19 O1 C.r-1� �l v Low Flow Threshold for POC 1 : 50 Percent of the 2 Year High Flow Threshold for POC 1: 50 year 5�2�r � Is123 37/195 PREDEVELOPED LAND USE Name . Basin 1 Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .098 Pervious Total 0.098 Impervious Land Use acre Impervious Total 0 Basin Total 0.098 Element Flows To: Surface Interflow MITIGATED LAND USE Name . Basin 1 Bypass: No GroundWater: No Pervious Land Use acre A B, Lawn, Flat .0006 Pervious Total 0.0006 Impervious Land Use acre ROOF TOPS FLAT 0.0615 DRIVEWAYS FLAT 0.0162 SIDEWALKS FLAT 0.0197 Impervious Total 0.0974 Basin Total 0.098 Groundwater 38/195 Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 Name : Gravel Trench Bed 1 Bottom Length: 38.00 ft. Bottom Width: 3.33 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 2 Pour Space of material for first layer: 0.35 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 �� (A Infiltration On Infiltration rate: 4.2 Infiltration safety factor: 3.7 �� C e , , .(JAC Total Volume Infiltrated (ac-ft.): 34.825 Total Volume Through Riser (ac-ft.): 0.001 Total Volume Through- Percent Infiltrated: 100 ity (ac-ft.): 34.826 Total Precip Applied cility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 2 ft. Riser Diameter: 48 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.002 0.000 0.000 0.000 0.0222 0.002 0.000 0.000 0.045 0.0444 0.002 0.000 0.000 0.045 0.0667 0.002 0.000 0.000 0.045 0.0889 0.002 0.000 0.000 0.045 0.1111 0.002 0.000 0.000 0.045 0.1333 0.002 0.000 0.000 0.045 0.1556 0.002 0.000 0.000 0.045 0.1778 0.002 0.000 0.000 0.045 0.2000 0.002 0.000 0.000 0.045 0.2222 0.002 0.000 0.000 0.045 0.2444 0.002 0.000 0.000 0.045 0.2667 0.002 0.000 0.000 0.045 0.2889 0.002 0.000 0.000 0.045 0.3111 0.002 0.000 0.000 0.045 0.3333 0.002 0.000 0.000 0.045 0.3556 0.002 0.000 0.000 0.045 0.3778 0.002 0.000 0.000 0.045 0.4000 0.002 0.000 0.000 0.045 39/195 0.4222 0.002 0.000 0.000 0.045 0.4444 0.002 0.000 0.000 0.045 0.4667 0.002 0.000 0.000 0.045 0.4889 0.002 0.000 0.000 0.045 0.5111 0.002 0.000 0.000 0.045 0.5333 0.002 0.000 0.000 0.045 0.5556 0.002 0.000 0.000 0.045 0.5778 0.002 0.000 0.000 0.045 0.6000 0.002 0.000 0.000 0.045 0.6222 0.002 0.000 0.000 0.045 0.6444 0.002 0.000 0.000 0.045 0.6667 0.002 0.000 0.000 0.045 0.6889 0.002 0.000 0.000 0.045 0.7111 0.002 0.000 0.000 0.045 0.7333 0.002 0.000 0.000 0.045 0.7556 0.002 0.000 0.000 0.045 0.7778 0.002 0.000 0.000 0.045 0.8000 0.002 0.000 0.000 0.045 0.8222 0.002 0.000 0.000 0.045 0.8444 0.002 0.000 0.000 0.045 0.8667 0.002 0.000 0.000 0.045 0.8889 0.002 0.000 0.000 0.045 0.9111 0.002 0.000 0.000 0.045 0.9333 0.002 0.000 0.000 0.045 0.9556 0.002 0.001 0.000 0.045 0.9778 0.002 0.001 0.000 0.045 1.0000 0.002 0.001 0.000 0.045 1.0222 0.002 0.001 0.000 0.045 1.0444 0.002 0.001 0.000 0.045 1.0667 0.002 0.001 0.000 0.045 1.0889 0.002 0.001 0.000 0.045 1.1111 0.002 0.001 0.000 0.045 1.1333 0.002 0.001 0.000 0.045 1.1556 0.002 0.001 0.000 0.045 1.1778 0.002 0.001 0.000 0.045 1.2000 0.002 0.001 0.000 0.045 1.2222 0.002 0.001 0.000 0.045 1.2444 0.002 0.001 0.000 0.045 1.2667 0.002 0.001 0.000 0.045 1.2889 0.002 0.001 0.000 0.045 1.3111 0.002 0.001 0.000 0.045 1.3333 0.002 0.001 0.000 0.045 1.3556 0.002 0.001 0.000 0.045 1.3778 0.002 0.001 0.000 0.045 1.4000 0.002 0.001 0.000 0.045 1.4222 0.002 0.001 0.000 0.045 1.4444 0.002 0.001 0.000 0.045 1.4667 0.002 0.001 0.000 0.045 1.4889 0.002 0.001 0.000 0.045 1.5111 0.002 0.001 0.000 0.045 1.5333 0.002 0.001 0.000 0.045 1.5556 0.002 0.001 0.000 0.045 1.5778 0.002 0.001 0.000 0.045 1.6000 0.002 0.001 0.000 0.045 1.6222 0.002 0.001 0.000 0.045 1.6444 0.002 0.001 0.000 0.045 1.6667 0.002 0.001 0.000 0.045 1.6889 0.002 0.001 0.000 0.045 1.7111 0.002 0.001 0.000 0.045 40/195 1.7333 0.002 0.001 0.000 0.045 1.7556 0.002 0.001 0.000 0.045 1.7778 0.002 0.001 0.000 0.045 1.8000 0.002 0.001 0.000 0.045 1.8222 0.002 0.001 0.000 0.045 1.8444 0.002 0.001 0.000 0.045 1.8667 0.002 0.001 0.000 0.045 1.8889 0.002 0.001 0.000 0.045 1.9111 0.002 0.001 0.000 0.045 1.9333 0.002 0.002 0.000 0.045 1.9556 0.002 0.002 0.000 0.045 1.9778 0.002 0.002 0.000 0.045 2.0000 0.002 0.002 0.000 0.045 41/195 ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.098 Total Impervious Area:O Mitigated Landuse Totals for POC #1 Total Pervious Area:0.0006 Total Impervious Area:0.0974 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000049 5 year 0.000064 10 year 0.000072 25 year 0.000079 50 year 0.000084 100 year 0.000088 Flow Frequency Return Periods for Mitigated Return Period Flow(cfs) 2 year 0 POC #1 pp () j�ADt+,j - -1 �v 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 �Mralyvs F.i [low Frequency t0 Cumulative Pfobablldy 10 clot (oH) 0501 1Sm 0701 15m 0801 15m 2 Year 0.0000 0.0293 0.0000 5 Year 0.0001 0.0396 0.0000 0.1 - 01 10 Year 0.0001 0.0472 0.0000 25 Year 0.0001 0.0579 0.0000 50 Year 0.0001 0.0667 0.0000 0.01 100 Year - 0.0001 0.0761 0.0000 ,a 601 200 Year - 0.0001 0.0869 0.0000 b 500 Year - 0.0001 0.0992 0.0000 0 001 701 • E01 Annual Peaks 1902 0.0000 0.0344 0.0000 0.0001 1903 0.0000 0.0375 0.0000 ++ + 1904 0.0000 0.0412 0.0000 1905 0.0000 0.0204 0.0000 0.0 + �+ 4N NIhH-+ 0,° 1906 0.0000 0.0215 0.0000 0.6 1 2 6 10 20 30 50 70 60 90 95 98 9999.51 1907 0.0001 0,0269 0.0000 1908 0.0001 0.0245 0.0000 SUean Pldadion Ovation LID Ovation Flow Fr Waie10 1-10opraph I 1909 0.0001 0.0315 0.0000 WetlaldlnpdVohmse LIDRe t RechaigeDwa6on Recha9ePledeveloped -- Recha9eMdkWi,d I 1921 1911 0.0001 0.0001 0.0325 0.0325 0.0000 0.0000 Analyze dalassb Compact WDM Delete Selected r Mod*FF �] 1912 0.0001 0.0535 0.0000 Daat*nClwl 1913 0.0000 0.0211 0.0000 1914 0.0001 0.0855 0.0000 -� 1913 0.0000 0.0191 0.0000 4;ajilialll 1916 0.0001 0.0367 0,0000 1000GIevel Trench Bed I ALL OUTLETS 1,14gated 1917 0.0000 0.0179 0.0000 1001GlevelTlenchEl 1OUTLET 1Mitpeled 1918 0.0000 0.0291 0.0000 1002GravelTlerx1h dIOUTLET2Miipaled 1919 0.0000 0.0174 0.0000 1920 0.0001 0.0247 0.0000 1921 0.0000 0.0190 0.0000 _ AlOalefNs Fbw Slage Pretp EvaP POC1 + 1922 0.0000 0.0280 0.0000 FbodFe°uencyMelhod 1923 0.0001 0.0244 0.0000 (� Log Peason Type 111178 1924 0.0000 0.0406 0.0000 Wei 1925 0.0000 0.0181 0.0000 7 CwiO 1926 0.0001 0.0371 0.0000 Gligaten 1927 0.0001 0.0275 0.0000 42/195 Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1902 0.000 0.000 1903 0.000 0.000 1904 0.000 0.000 1905 0.000 0.000 1906 0.000 0.000 1907 0.000 0.000 1908 0.000 0.000 1909 0.000 0.000 1910 0.000 0.000 1911 0.000 0.000 1912 0.000 0.000 1913 0.000 0.000 1914 0.000 0.000 1915 0.000 0.000 1916 0.000 0.000 1917 0.000 0.000 1918 0.000 0.000 1919 0.000 0.000 1920 0.000 0.000 1921 0.000 0.000 1922 0.000 0.000 1923 0.000 0.000 1924 0.000 0.000 1925 0.000 0.000 1926 0.000 0.000 1927 0.000 0.000 1928 0.000 0.000 1929 0.000 0.000 1930 0.000 0.000 1931 0.000 0.000 1932 0.000 0.000 1933 0.000 0.000 1934 0.000 0.000 1935 0.000 0.000 1936 0.000 0.000 1937 0.000 0.000 1938 0.000 0.000 1939 0.000 0.000 1940 0.000 0.000 1941 0.000 0.000 1942 0.000 0.000 1943 0.000 0.000 1944 0.000 0.000 1945 0.000 0.000 1946 0.000 0.000 1947 0.000 0.000 1948 0.000 0.000 1949 0.000 0.000 1950 0.000 0.000 1951 0.000 0.000 1952 0.000 0.000 1953 0.000 0.000 1954 0.000 0.000 1955 0.000 0.000 1956 0.000 0.000 1957 0.000 0.000 43/195 1958 0.000 0.000 1959 0.000 0.000 1960 0.000 0.000 1961 0.000 0.000 1962 0.000 0.000 1963 0.000 0.000 1964 0.000 0.000 1965 0.000 0.000 1966 0.000 0.000 1967 0.000 0.000 1968 0.000 0.000 1969 0.000 0.000 1970 0.000 0.000 1971 0.000 0.000 1972 0.000 0.035 1973 0.000 0.000 1974 0.000 0.000 1975 0.000 0.000 1976 0.000 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.000 0.000 1980 0.000 0.000 1981 0.000 0.000 1982 0.000 0.000 1983 0.000 0.000 1984 0.000 0.000 1985 0.000 0.000 1986 0.000 0.000 1987 0.000 0.000 1988 0.000 0.000 1989 0.000 0.000 1990 0.000 0.000 1991 0.000 0.000 1992 0.000 0.000 1993 0.000 0.000 1994 0.000 0.000 1995 0.000 0.000 1996 0.000 0.000 1997 0.000 0.000 1998 0.000 0.000 1999 0.000 0.000 2000 0.000 0.000 2001 0.000 0.000 2002 0.000 0.000 2003 0.000 0.000 2004 0.000 0.000 2005 0.000 0.000 2006 0.000 0.000 2007 0.000 0.000 2008 0.000 0.000 2009 0.000 0.000 2010 0.000 0.000 2011 0.000 0.000 2012 0.000 0.000 2013 0.000 0.000 2014 0.000 0.000 2015 0.000 0.000 2016 0.000 0.000 44/195 2017 0.000 0.000 2018 0.000 0.000 2019 0.000 0.000 2020 0.000 0.000 2021 0.000 0.000 2022 0.000 0.000 2023 0.000 0.000 2024 0.000 0.000 2025 0.000 0.000 2026 0.000 0.000 2027 0.000 0.000 2028 0.000 0.000 2029 0.000 0.000 2030 0.000 0.000 2031 0.000 0.000 2032 0.000 0.000 2033 0.000 0.000 2034 0.000 0.000 2035 0.000 0.000 2036 0.000 0.000 2037 0.000 0.000 2038 0.000 0.000 2039 0.000 0.000 2040 0.000 0.000 2041 0.000 0.000 2042 0.000 0.000 2043 0.000 0.000 2044 0.000 0.000 2045 0.000 0.000 2046 0.000 0.000 2047 0.000 0.000 2048 0.000 0.000 2049 0.000 0.000 2050 0.000 0.000 2051 0.000 0.000 2052 0.000 0.000 2053 0.000 0.000 2054 0.000 0.000 2055 0.000 0.000 2056 0.000 0.000 2057 0.000 0.000 2058 0.000 0.000 45/195 Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0001 0.0347 2 0.0001 0.0000 3 0.0001 0.0000 4 0.0001 0.0000 5 0.0001 0.0000 6 0.0001 0.0000 7 0.0001 0.0000 8 0.0001 0.0000 9 0.0001 0.0000 10 0.0001 0.0000 11 0.0001 0.0000 12 0.0001 0.0000 13 0.0001 0.0000 14 0.0001 0.0000 15 0.0001 0.0000 16 0.0001 0.0000 17 0.0001 0.0000 18 0.0001 0.0000 19 0.0001 0.0000 20 0.0001 0.0000 21 0.0001 0.0000 22 0.0001 0.0000 23 0.0001 0.0000 24 0.0001 0.0000 25 0.0001 0.0000 26 0.0001 0.0000 27 0.0001 0.0000 28 0.0001 0.0000 29 0.0001 0.0000 30 0.0001 0.0000 31 0.0001 0.0000 32 0.0001 0.0000 33 0.0001 0.0000 34 0.0001 0.0000 35 0.0001 0.0000 36 0.0001 0.0000 37 0.0001 0.0000 38 0.0001 0.0000 39 0.0001 0.0000 40 0.0001 0.0000 41 0.0001 0.0000 42 0.0001 0.0000 43 0.0001 0.0000 44 0.0001 0.0000 45 0.0001 0.0000 46 0.0001 0.0000 47 0.0001 0.0000 48 0.0001 0.0000 49 0.0001 0.0000 50 0.0001 0.0000 51 0.0001 0.0000 52 0.0001 0.0000 53 0.0001 0.0000 54 0.0001 0.0000 55 0.0001 0.0000 56 0.0001 0.0000 0000'0 0000'0 STT 0000'0 0000'0 bTT 0000'0 0000'0 ETT 0000'0 0000'0 ZTT 0000'0 0000'0 TTT 0000'0 0000'0 OTT 0000'0 0000'0 60T 0000'0 0000'0 80T 0000'0 0000'0 LOT 0000'0 0000'0 90T 0000'0 0000'0 SOT 0000'0 0000'0 60T 0000'0 0000'0 EOT 0000'0 0000'0 N T 0000'0 0000'0 TOT 0000'0 0000'0 OOT 0000'0 0000'0 66 0000'0 0000'0 86 0000'0 0000'0 L6 0000'0 0000'0 96 0000'0 0000'0 S6 0000'0 0000'0 66 0000'0 0000'0 E6 0000'0 0000'0 Z6 0000'0 0000'0 T6 0000'0 0000'0 06 0000'0 0000'0 68 0000'0 0000'0 88 0000'0 0000'0 L8 0000'0 0000'0 98 0000'0 0000'0 S8 0000'0 0000'0 b8 0000'0 0000'0 E8 0000'0 0000'0 Z8 0000'0 0000'0 T8 0000'0 0000'0 08 0000'0 0000'0 6L 0000'0 0000'0 8L 0000'0 0000'0 LL 0000'0 0000'0 9L 0000'0 0000'0 SL 0000'0 T000'0 bL 0000'0 T000'0 EL 0000'0 T000'0 ZL 0000'0 T000'0 TL 0000'0 T000'0 OL 0000'0 T000'0 69 0000'0 T000'O 89 0000'0 T000'0 L9 0000'0 T000'0 99 0000'0 T000'0 S9 0000'0 T000'0 b9 0000'0 T000'0 E9 0000'0 T000'0 Z9 0000'0 T000'0 T9 0000'0 T000'O 09 0000'0 T000'O 6S 0000'0 T000'0 8S 0000'0 T000'O LS 96 �/9t 47/195 116 0.0000 0.0000 117 0.0000 0.0000 118 0.0000 0.0000 119 0.0000 0.0000 120 0.0000 0.0000 121 0.0000 0.0000 122 0.0000 0.0000 123 0.0000 0.0000 124 0.0000 0.0000 125 0.0000 0.0000 126 0.0000 0.0000 127 0.0000 0.0000 128 0.0000 0.0000 129 0.0000 0.0000 130 0.0000 0.0000 131 0.0000 0.0000 132 0.0000 0.0000 133 0.0000 0.0000 134 0.0000 0.0000 135 0.0000 0.0000 136 0.0000 0.0000 137 0.0000 0.0000 138 0.0000 0.0000 139 0.0000 0.0000 140 0.0000 0.0000 141 0.0000 0.0000 142 0.0000 0.0000 143 0.0000 0.0000 144 0.0000 0.0000 145 0.0000 0.0000 146 0.0000 0.0000 147 0.0000 0.0000 148 0.0000 0.0000 149 0.0000 0.0000 150 0.0000 0.0000 151 0.0000 0.0000 152 0.0000 0.0000 153 0.0000 0.0000 154 0.0000 0.0000 155 0.0000 0.0000 156 0.0000 0.0000 157 0.0000 0.0000 48/195 Stream Protection Duration POC #1 The Facility PASSED Facility FAILED duration standard for 1+ flows. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0000 4538 2 0 Pass 0.0000 4369 2 0 Pass 0.0000 4179 2 0 Pass 0.0000 4040 2 0 Pass 0.0000 3885 2 0 Pass 0.0000 3706 2 0 Pass 0.0000 3553 2 0 Pass 0.0000 3394 2 0 Pass 0.0000 3269 2 0 Pass 0.0000 3105 2 0 Pass 0.0000 2973 2 0 Pass 0.0000 2866 2 0 Pass 0.0000 2737 2 0 Pass 0.0000 2661 2 0 Pass 0.0000 2561 2 0 Pass 0.0000 2467 2 0 Pass 0.0000 2383 2 0 Pass 0.0000 2279 2 0 Pass 0.0000 2196 2 0 Pass 0.0000 2100 2 0 Pass 0.0000 2019 2 0 Pass 0.0000 1940 2 0 Pass 0.0000 1846 2 0 Pass 0.0000 1759 2 0 Pass 0.0000 1680 2 0 Pass 0.0000 1590 2 0 Pass 0.0000 1502 2 0 Pass 0.0000 1403 2 0 Pass 0.0000 1332 2 0 Pass 0.0000 1280 2 0 Pass 0.0000 1203 2 0 Pass 0.0000 1163 2 0 Pass 0.0000 1109 2 0 Pass 0.0000 1066 2 0 Pass 0.0000 1014 2 0 Pass 0.0000 960 2 0 Pass 0.0000 923 2 0 Pass 0.0000 880 2 0 Pass 0.0000 848 2 0 Pass 0.0000 823 2 0 Pass 0.0000 798 2 0 Pass 0.0000 768 2 0 Pass 0.0000 742 2 0 Pass 0.0001 715 2 0 Pass 0.0001 681 2 0 Pass 0.0001 625 2 0 Pass 0.0001 601 2 0 Pass 0.0001 572 2 0 Pass 0.0001 515 2 0 Pass 0.0001 491 2 0 Pass 0.0001 481 2 0 Pass 0.0001 455 2 0 Pass 49/195 0.0001 431 2 0 Pass 0.0001 409 2 0 Pass 0.0001 394 2 0 Pass 0.0001 376 2 0 Pass 0.0001 352 2 0 Pass 0.0001 338 2 0 Pass 0.0001 320 2 0 Pass 0.0001 310 2 0 Pass 0.0001 303 2 0 Pass 0.0001 291 2 0 Pass 0.0001 269 2 0 Pass 0.0001 246 2 0 Pass 0.0001 242. 2 0 Pass 0.0001 234 2 0 Pass 0.0001 227 2 0 Pass 0.0001 211 2 0 Pass 0.0001 189 2 1 Pass 0.0001. 187 2 1 Pass 0.0001 184 2 1 Pass 0.0001 171 2 1 Pass 0.0001 161 2 1 Pass 0.0001 146 2 1 Pass 0.0001 127 2 1 Pass 0.0001 124 2 1 Pass 0.0001 118 2 1 Pass 0.0001 ill 2 1 Pass 0.0001 99 2 2 Pass 0.0001 94 2 2 Pass 0.0001 83 2 2 Pass 0.0001 74 2 2 Pass 0.0001 59 2 3 Pass 0.0001 56 2 3 Pass 0.0001 49 2 4 Pass 0.0001 46 2 4 Pass 0.0001 31 2 6 Pass 0.0001 27 2 7 Pass 0.0001 19 2 10 Pass 0.0001 4 2 50 Pass 0.0001 2 2 100 Pass 0.0001 0 2 n/a Fail 0.0001 0 2 n/a Fail 0.0001 0 2 n/a Fail 0.0001 0 2 n/a Fail 0.0001 0 2 n/a Fail 0.0001 0 2 n/a Fail 0.0001 0 2 n/a Fail 0.0001. 0 2 n/a Fail 0.0001 0 2 n/a Fai.l. The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. 50/195 Water Quality B.MP Flow and Volume for POC N1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. LID Report LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Infiltrated Treated Treatment Facility (ac-ft.) Infiltration (ac-ft) (ac-ft) Credit Gravel Trench Bed 1 POC Y 31.69 34.83 34.82 Y 100.00 34.82 100.00 Treat. Credit Total Volume Infiltrated 31.69 34.83 34.82 100.00 34.82 35 / 35 - 1008Treat. Credit - 100% Compliance with LID Standard 8 Duration Analysis Result = Passed POC 1 LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft) Innitiallon Infiltrated Treated (ac-f) (ac-ft) Credit Gra•:el Trench Bed 1 POC 0 3169 34.83 34.82 0 100.00 3C82 100-00 Treat- Credit Total Volume Infiltrated 31,69 3483 3482 100.00 34,82 35135 = 100% Treat Credit = 100% Anshan Compliance with LID analysis Standard 8% of 2-yr to 50% of Result = 2 yr Passed Perind and Impind Changes No changes have been made. This program and accompanying documentation are provided 'as -is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright ® by Clear Creek Solutions, Inc. 2005-2024; All Rights Reserved. 51/195 Appendix: Schematic Drainage System Design Sketch of Proposed System up Ryner-Raman Category 1 Drainage Plan Page 18 Raman 1050 Walnut St. Schematic Drainage Plcn Center Line Prop. j Prop. Off —site Off —site Driveway l Driveway � to Gutter. — — ;i _ to Infilt. Walnut ut tret ii� _ o C�rb I �' 14' R. Tree Fllowl /� ,® \ \ Protection l h —� �31 Circle / —--- -0-- Prop. _ Prop. on site Driveway to -- _____--------- — ------ ___---_ - ---------------- --------- ------------- ---- , T 3.33'x38' Infiltration Infiltration --- — -__-__-- ?�' Trench Tr nGh Es. Driveway l ` J------------ Ir ---- -- _ — _ Bottom 315' 14' I i l I II Prop. SFR Roof (I i l i to Downspouts to l lit Infiltration Trench I CA � �I II o I i II Prop. Covered -� l l II Entry / Patio l i — (I� r------ __-_-_-_--__ _ 7 * ----------- A;S� li Prop. Concrete Patio & Walkway lope to Yard O Drain to nfilt. Ex. 10' Sewer Eamt.l I ,A AFN: 8206280085 , \ V 31 \� ' \ I I Prep. 4• Sewer Ea t. � \ Recorded Prior to ermit Fild I � � I Footing Drains to 4'x4' Drywell I � �GRAPHIC SCALE 0 10 20 NORTH (IN FEET) 1 inch = 20 ft. 52/195 1/4/23 53/195 Appendix: Soil Management Plan -Compost and Topsoil Checklist Page 19 Print F 5 Use Achieving the Post -construction Soil Standard booklet instructions to carry out this Soil Management Plan. Project Information Complete all information on page 1, onlysite address Area: and permit number on additional pages. (refer to lettered areas mapped on site plan) Site address/Lot 1050 Walnut Street. Edmonds Square footage:2,489 No. Permit Type LDA Selected soil treatment option: ❑ Option 1 ❑ Option 2 ® Option 3 ❑ Option 4 Permit Number If using option 2, select type of amendment rate: Permit Holder ❑ Pre -approved (2") ❑ Custom with % Target Soil Organic Matter Phone Area: (refer to lettered areas mapped on site plan) Mailing Address 4224 21 lth Ave SE, Snohomish 98290 Square footage: Selected soil treatment option: ❑ Option 1 ❑ Option 2 Contact Person Eric Ryner -Ryner Homes ❑ Option 3 ❑ Option 4 Phone 425-328-5617 If using option 2, select type of amendment rate: ❑ Pre -approved (2") ❑ Custom with % Target Soil Plan Prepared By Rick Heide P.E. _ Organic Matter Attachments - attach the following to this plan: Area: (refer to lettered areas mapped on site plan) * Scale stormwater site plan drawings that include areas to be treated with Soil Treatment Options 1, 2, 3, 4. Square footage: * Completed Compost and Topsoil Calculation Worksheet results. Selected soil treatment option: Option 1 ❑ Option 2 ❑ * Original compost and/or topsoil test results reports demonstrating that products contain adequate organic matter (for soil treatment options 2) and meet topsoil soil quality standard. Note: Retain original delivery tickets for compost and/or topsoil products for verifi cation purposes. Soil Treatment Options for Areas Identified on Site Plan Soil treatment options available: *Option 1 — Leave native soil undisturbed, and protect from compaction during construction, *Option 2 — Amend existing soil in place. *Option 3 — For native soil: stockpile site duff and topsoil, and reapply after grading and construction. *Option 4 — Import topsoil mix with 8-13% soil organic matter content. FOR PDS USE ONLY Plan Approval Record Reviewer: Approved sions Required: ❑ Option 3 ❑ Option 4 If using option 2, select type of amendment rate: ❑ Pre -approved (2") ❑ Custom with % Target Soil _Organic Matter Record the compost and/or topsoil products to be used Compost Product 41: Test Results % organic matter: Quantity in cubic yards Supplier Compost Product 42: Test Results % organic matter: Supplier Topsoil Product #3: Test Results % organic matter: Supplier Topsoil Product 44: Quantity in cubic yards Quantity in cubic yards ate: Reviewer: Approved: _ Test Results =visions Required: organic matter: Quantity in cubic yards Supplier Total cubic yards compost: Total cubic yards topsoil: 55/195 Soil Treatment Options There are four Soil Treatment Options that can be used to meet the post - construction soil standard. These options can be used individually, or in combination (more than one may be used in different areas of a single site), so that they work best for the situation. The most convenient and economical methods for achieving the standards depend on site soil conditions, grading and subgrade compaction, practicality of stockpiling site topsoil during grading, and site access issues. Choose Options 1, 2, 3 and/or 4 in areas where grading and soil disturbance are unavoidable, and follow the attached design guidelines : Option 1: Leave native soil undisturbed, and protect from compaction during con- struction. NOTE: Option 1 is only applicable to sites that haw the original, undisturbed soil native to the site. 7his will most gllen be forested land that is being left un- disturbed hi the current project. This option is the most economical and best for the environment, but is not always feasible. • Plan site development to leave areas where native vegetation does not need to be dis- turbed. • Fence off areas of native vegetation on the site that will not be stripped, logged, or graded to protect them from disturbance during con- struction. • Undisturbed areas do not require soil amend- ment. Option 2: Amend disturbed soil according to the following procedures: a. Scarify subsoil to a depth of one foot. b. In planting beds, place three inches of com- post and till in to an eight -inch depth. c. In turf areas, place two inches of compost and till in to an eight -inch depth. d. Apply two to four inches of arborist wood chip, coarse bark mulch, or compost mulch to planting beds after final planting. Alternatively, disturbed soil can be amended on a site -customized manner so that it meets the soil quality criteria set forth above, as dctcr- mined by a licensed engineer, geologist, land- scape architect, or other person as approved by Snohomish County. Note: MR S is triggered on sites with mote than 2,000 sq. ft. of new, replaced, or new plus replaced impewious surface, or 7, 000 sq. ft or greater oqf land disturbing activity. 56/195 Option 3: Disturbed Soil. Stockpile existing topsoil during grading and replace it prior to planting. Stockpiled topsoil must be amended if needed to meet the organic matter and depth requirements by following the procedures in option (2). Remove forest duff layer and topsoil and stockpile separately, in an approved lo- cation prior to grading. Cover soil and duff piles with woven weed barrier (available from nursery supply stores) that sheds moisture yet allows airflow. Option 4: Import topsoil mix with 8-13% soil organic mat- ter content. I n1port topsoil mix of sufficient organic content and depth to meet the organic matter and depth requirements. What is the human impact on soils? 15-30% evapo- 15%transpiration 0% surface water rainfall o detained/ detained 55-70 /o infiltrated surface water runoff C (carries pesticides, silt and animal waste) �- - A � . Subsoil Groundwater Bedrock Note: MR S is triggered on sites with ►pore than 2, 000 sq. ft. of new, replaced, or new plus replaced impervious surface, or 7, 000 sq. ft. or greater of land disturbing activity. Compost and Topsoil Calculation Worksheet for the Pre -approved Amend- ment Rate NOTE: For Options 2 and 3, use this worksheet if you plan to use the pre -approved compost amendment rate of 2 inches. This worksheet should not be used if a custom compost amendment rate is selected for Options 2 and/ or 3. Leave native soil undisturbed, and protect from compaction during construc- tion. • Enter lettered areas from site plan where this option will be used: No calculations for compost or topsoil are necessamy for this option. Amend existing soil in -place (2-inch layer of compost). • Enter lettered areas from site plan where this option will be used: Enter combined square footage of lettered areas in thousands (example: for 4,525 sq ft, enter 4.525; for 500 sq ft, enter 0.5) Multiply combined square footage by 6.2 and enter_product in box A A=Cubic Yards AMOUNT OF COMPOST NEEDED FOR THESE ARE- AS Note: MR 5 is triggered on sites ivith more than 2,000 sq.,ft. ofnew, replaced, or new phis replaced impervious surface, or 7, 000 sq. , ft, or greater of land disturbing activity. 58/195 Option 3 Native Soil — stockpile site duff and topsoil and reapply after grading and con- struction. • Enter lettered areas from site plan where this option will be used: Enter combined square footage of lettered areas in thousands 2.489 (example: for 4,525 sq ft, enter 4.525; for 500 sq ft, enter 0.5) Multiply combined square footage by 25 and enter product in box B: B 62 =Cubic Yards AMOUNT OF TOPSOIL TO BE STOCKPILED AND REAPPLIED IN THESE AREAS Import topsoil. • Enter lettered areas from site plan where this option will be used: • Enter combined square footage of lettered areas in thousands (example: for 4,525 sq ft, enter 4.525; for 500 sq ft, enter 0.5) • Multiply combined square footage by 25 and enter product in box C: C=Cubic Yards AMOUNT OF IMPORTED TOPSOIL NEEDED FOR THESE AREAS Order These Amounts: Enter amount in Box A: Enter amount in Box C : Cubic Yards of Compost Cubic Yards of Topsoil Note: MR 5 is triggered on sites with more than 2, 000 sq. ft. of new, replaced, or new plus replaced impervious sun face, or 7, 000 sq. ft. or greater of land disturbing activity. 59/195 Appendix: Operations Manual — BMP's Ryner-Raman Category 1 Drainage Plan 60/195 BMP C101: Preserving Natural Vegetation Purpose The purpose of preserving natural vegetation is to reduce erosion wherever practicable. Limiting site disturbance is the single most effective method for reducing erosion. For example, conifers can hold up to about 50 percent of all rain that falls during a storm. Up to 20-30 percent of this rain may never reach the ground but is taken up by the tree or evaporates. Another benefit is that the rain held in the tree can be released slowly to the ground after the storm. Conditions of Use Natural vegetation should be preserved on steep slopes, near perennial and intermittent water- courses or swales, and on building sites in wooded areas. . As required by local governments. Phase construction to preserve natural vegetation on the project site for as long as possible during the construction period. Design and Installation Specifications Natural vegetation can be preserved in natural clumps or as individual trees, shrubs and vines. The preservation of individual plants is more difficult because heavy equipment is generally used to remove unwanted vegetation. The points to remember when attempting to save individual plants are: . Is the plant worth saving? Consider the location, species, size, age, vigor, and the work involved. Local governments may also have ordinances to save natural vegetation and trees. Fence or clearly mark areas around trees that are to be saved. It is preferable to keep ground disturbance away from the trees at least as far out as the dripline. Plants need protection from three kinds of injuries: Construction Equipment- This injury can be above or below the ground level. Damage results from scarring, cutting of roots, and compaction of the soil. Placing a fenced buffer zone around plants to be saved prior to construction can prevent construction equipment injuries. Grade Changes- Changing the natural ground level will alter grades, which affects the plant's ability to obtain the necessary air, water, and minerals. Minor fills usually do not cause prob- lems although sensitivity between species does vary and should be checked. Trees can typ- ically tolerate fill of 6 inches or less. For shrubs and other plants, the fill should be less. When there are major changes in grade, it may become necessary to supply air to the roots of plants. This can be done by placing a layer of gravel and a tile system over the roots before the fill is made. The tile system should be laid out on the original grade leading from a dry well 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 271 61/195 around the tree trunk. The system should then be covered with small stones to allow air to cir- culate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest per- centage of the plant roots are in the upper 12 inches of the soil and cuts of only 2-3 inches can cause serious injury. To protect the roots it may be necessary to terrace the immediate area around the plants to be saved. If roots are exposed, construction of retaining walls may be needed to keep the soil in place. Plants can also be preserved by leaving them on an undis- turbed, gently sloping mound. To increase the chances for survival, it is best to limit grade changes and other soil disturbances to areas outside the dripline of the plant. Excavations - Protect trees and other plants when excavating for drainfields, power, water, and sewer lines. Where possible, the trenches should be routed around trees and large shrubs. When this is not possible, it is best to tunnel under them. This can be done with hand tools or with power augers. If it is not possible to route the trench around plants to be saved, then the following should be observed: Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends with a wood dressing like asphalt base paint if roots will be exposed for more than 24-hours. Backfill the trench as soon as possible. Tunnel beneath root systems as close to the center of the main trunk to preserve most of the important feeder roots. Some problems that can be encountered with a few specific trees are: • Maple, Dogwood, Red alder, Western hemlock, Western red cedar, and Douglas fir do not readily adjust to changes in environment and special care should be taken to protect these trees. . The windthrow hazard of Pacific silver fir and madrona is high, while that of Western hemlock is moderate. The danger of windthrow increases where dense stands have been thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep) have a low windthrow hazard. • Cottonwoods, maples, and willows have water -seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions that other trees would not. . Thinning operations in pure or mixed stands of Grand fir, Pacific silver fir, Noble fir, Sitka spruce, Western red cedar, Western hemlock, Pacific dogwood, and Red alder can cause ser- ious disease problems. Disease can become established through damaged limbs, trunks, roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect attack. Maintenance Standards Inspect flagged and/or fenced areas regularly to make sure flagging or fencing has not been removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 272 62/195 If tree roots have been exposed or injured, "prune" cleanly with an appropriate pruning saw or top- pers directly above the damaged roots and recover with native soils. Treatment of sap flowing trees (fir, hemlock, pine, soft maples) is not advised as sap forms a natural healing barrier. 2019 Stormwater Management Manual for Western Washington Volume ll - Chapter 3 - Page 273 63/195 BMP C102: Buffer Zones Purpose Creation of an undisturbed area or strip of natural vegetation or an established suitable planting that will provide a living filter to reduce soil erosion and stormwater runoff velocities. Conditions of Use Buffer zones are used along streams, wetlands and other bodies of water that need protection from erosion and sedimentation. Contractors can use vegetative buffer zone BMPs to protect natural swales and they can incorporate them into the natural landscaping of an area. Do not use critical -areas buffer zones as sediment treatment areas. These areas shall remain com- pletely undisturbed. The local permitting authority may expand the buffer widths temporarily to allow the use of the expanded area for removal of sediment. The types of buffer zones can change the level of protection required as shown below: Designated Critical Area Buffers - buffers that protect Critical Areas, as defined by the Washington State Growth Management Act, and are established and managed by the local permitting authority. These should not be disturbed and must protected with sediment control BMPs to prevent impacts. The local permitting authority may expand the buffer widths temporarily to allow the use of the expan ded area for removal of sediment. Vegetative Buffer Zones - areas that may be identified in undisturbed vegetation areas or managed vegetation areas that are outside any Designated Critical Area Buffer. They may be utilized to provide an additional sediment control area and/or reduce runoff velocities. If being used for pre- servation of natural vegetation, they should be arranged in clumps or strips. They can be used to pro- tect natural swales and incorporated into the natural landscaping area. Design and Installation Specifications • Preserving natural vegetation or plantings in clumps, blocks, or strips is generally the easiest and most successful method. • Leave all unstable steep slopes in natural vegetation. • Mark clearing limits and keep all equipment and construction debris out of the natural areas and buffer zones. Steel construction fencing is the most effective method to protect sensitive areas and buffers. Alternatively, wire -backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective. • Keep all excavations outside the dripline of trees and shrubs. • Do not push debris or extra soil into the buffer zone area because it will cause damage by 2019 Stormwater Management Manual for Western Washington Volume ll - Chapter 3 - Page 273 64/195 burying and smothering vegetation. . Vegetative buffer zones for streams, lakes or other waterways shall be established by the local permitting authority or other state or federal permits or approvals. Maintenance Standards Inspect the area frequently to make sure flagging remains in place and the area remains undis- turbed. Replace all damaged flagging immediately. Remove all materials located in the buffer area that may impede the ability of the vegetation to act as a filter. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 274 65/195 BMP C103: High -Visibility Fence Purpose High -visibility fencing is intended to: • Restrict clearing to approved limits. • Prevent disturbance of sensitive areas, their buffers, and other areas required to be left undis- turbed. . Limit construction traffic to designated construction entrances, exits, or internal roads. • Protect areas where marking with survey tape may not provide adequate protection. Conditions of Use To establish clearing limits plastic, fabric, or metal fence may be used: . At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. . As necessary to control vehicle access to and on the site. Design and Installation Specifications High -visibility plastic fence shall be composed of a high -density polyethylene material and shall be at least four feet in height. Posts for the fencing shall be steel or wood and placed every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color shall be high -visibility orange. The fence tensile strength shall be 360 Ibs/ft using the ASTM D4595 testing method. If appropriate install fabric silt fence in accordance with BMP C233: Silt Fence to act as high -visibility fence. Silt fence shall be at least 3 feet high and must be highly visible to meet the requirements of this BMP. Metal fences shall be designed and installed according to the manufacturer's specifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 274 66/195 Maintenance Standards If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 275 67/195 BMP C105: Stabilized Construction Access Purpose Stabilized construction accesses are established to reduce the amount of sediment transported onto paved roads outside the project site by vehicles or equipment. This is done by constructing a sta- bilized pad of quarry spalls at entrances and exits for project sites. Conditions of Use Construction accesses shall be stabilized wherever traffic will be entering or leaving a construction site if paved roads or other paved areas are within 1,000 feet of the site. For residential subdivision construction sites, provide a stabilized construction access for each res- idence, rather than only at the main subdivision entrance. Stabilized surfaces shall be of sufficient length/width to provide vehicle access/parking, based on lot size and configuration. On large commercial, highway, and road projects, the designer should include enough extra mater- ials in the contract to allow for additional stabilized accesses not shown in the initial Construction SWPPP. It is difficult to determine exactly where access to these projects will take place; additional materials will enable the contractor to install them where needed. Design and Installation Specifications See Figure II-3.1: Stabilized Construction Access for details. Note: the 1 00'minimum length of the access shall be reduced to the maximum practicable size when the size or configuration of the site does not allow the full length (100'). Construct stabilized construction accesses with a 12-inch thick pad of 4-inch to 8-inch quarry spalls, a 4-inch course of asphalt treated base (ATB), or use existing pavement. Do not use crushed con- crete, cement, or calcium chloride for construction access stabilization because these products raise pH levels in stormwater and concrete discharge to waters of the State is prohibited. A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the standards listed in Table 11-3.2: Stabilized Con- struction Access Geotextile Standards. Table 11-3.2: Stabilized Construction Access Geotextile Standards Geotextile Property I Required Value Grab Tensile Strength (ASTM D4751) 1 200 psi min. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 275 68/195 Table II-3.2: Stabilized Construction Access Geotextile Standards (continued) Geotextile Property Required Value Grab Tensile Elongation (ASTM D4632) 30% max. Mullen Burst Strength (ASTM D3786-80a) 400 psi min. AOS (ASTM D4751) 20-45 (U.S. standard sieve size) Consider early installation of the first lift of asphalt in areas that will be paved; this can be used as a stabilized access. Also consider the installation of excess concrete as a stabilized access. During large concrete pours, excess concrete is often available for this purpose. Fencing (see BMP C103: High -Visibility Fence) shall be installed as necessary to restrict traffic to the construction access. Whenever possible, the access shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. Construction accesses should avoid crossing existing sidewalks and back of walk drains if at all possible. If a construction access must cross a sidewalk or back of walk drain, the full length of the sidewalk and back of walk drain must be covered and protected from sediment leaving the site. Alternative Material Specification WSDOT has raised safety concerns about the Quarry Spall rock specified above. WSDOT observes that the 4-inch to 8-inch rock sizes can become trapped between Dually truck tires, and then released off -site at highway speeds. WSDOT has chosen to use a modified specification for the rock while continuously verifying that the Stabilized Construction Access remains effective. To remain effective, the BMP must prevent sediment from migrating off site. To date, there has been no per- formance testing to verify operation of this new specification. Jurisdictions may use the alternative specification, but must perform increased off -site inspection if they use, or allow others to use, it. Stabilized Construction Accesses may use material that meets the requirements of WSDOT's Stand- ard Specifications for Road, Bridge, and Municipal Construction Section 9-03.9(1) (WSDOT, 2016) for ballast except for the following special requirements. The grading and quality requirements are listed in Table II-3.3: Stabilized Construction Access Alternative Material Requirements. Table II-3.3: Stabilized Construction Access Alternative Material Requirements Sieve Size Percent Passing 2'/2" 99-100 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 276 69/195 Table II-3.3: Stabilized Construction Access Alternative Material Requirements (continued) Sieve Size Percent Passing 2" 65-100 3/4" 40-80 No. 4 5 max. No. 100 0-2 % Fracture 75 min. . All percentages are by weight. . The sand equivalent value and dust ratio requirements do not apply. The fracture requirement shall be at least one fractured face and will apply the combined aggregate retained on the No. 4 sieve in accordance with FOP for AASHTO T 335. Maintenance Standards Quarry spalls shall be added if the pad is no longer in accordance with the specifications. . If the access is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include replace- ment/cleaning of the existing quarry spalls, street sweeping, an increase in the dimensions of the access, or the installation of BMP C 106: Wheel Wash. Any sediment that is tracked onto pavement shall be removed by shoveling or street sweep- ing. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when high efficiency sweeping is inef- fective and there is a threat to public safety. If it is necessary to wash the streets, the con- struction of a small sump to contain the wash water shall be considered. The sediment would then be washed into the sump where it can be controlled. Perform street sweeping by hand or with a high efficiency sweeper. Do not use a non -high effi- ciency mechanical sweeper because this creates dust and throws soils into storm systems or conveyance ditches. Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed immediately. . If vehicles are entering or exiting the site at points other than the construction access(es), BMP C103: High -Visibility Fence shall be installed to control traffic. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 277 70/195 Upon project completion and site stabilization, all construction accesses intended as per- manent access for maintenance shall be permanently stabilized. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 278 71/195 Figure II-3.1: Stabilized Construction Access cu roadsi Notes: 1. Driveway shall meet the requirements of the permitting agency. 2. It is recommended that the access be crowned so that runoff drains off the pad. DEPARTMENT OF ECOLOGY State of Washington 12" minimum thickness NOT TO SCALE n. 1 b' min. Provide full width of ingress/egress area Stabilized Construction Access Revised June 2018 Please see http://www.ecy.wa.gov/cop3aVht.htm1 for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 279 72/195 Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology's website at: https:Hecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies 2019 Stormwater Management Manual for Western Washington Volume // - Chapter 3 - Page 280 73/195 BMP C120: Temporary and Permanent Seeding Purpose Seeding reduces erosion by stabilizing exposed soils. A well -established vegetative cover is one of the most effective methods of reducing erosion. Conditions of Use Use seeding throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. The optimum seeding windows for western Washington are April 1 through June 30 and September 1 through October 1. Between July 1 and August 30 seeding requires irrigation until 75 percent grass cover is established. Between October 1 and March 30 seeding requires a cover of mulch or an erosion control blanket until 75 percent grass cover is established. Review all disturbed areas in late August to early September and complete all seeding by the end of September. Otherwise, vegetation will not establish itself enough to provide more than average pro- tection. Mulch is required at all times for seeding because it protects seeds from heat, moisture loss, and transport due to runoff. Mulch can be applied on top of the seed or simultaneously by hydroseeding See BMP C121: Mulching for specifications. Seed and mulch all disturbed areas not otherwise vegetated at final site stabilization. Final sta- bilization means the completion of all soil disturbing activities at the site and the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (such as pavement, riprap, gabions, or geotextiles) which will prevent erosion. See BMP T5.13: Post -Construction Soil Qualitv and Depth. Design and Installation Specifications General Install channels intended for vegetation before starting major earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated channels that will have high flows, install erosion control blankets over the top of hydroseed. Before allowing water to flow in vegetated channels, establish 75 percent vegetation cover. If vegetated channels cannot be established by seed 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 284 74/195 before water flow; install sod in the channel bottom — over top of hydromulch and erosion con- trol blankets. • Confirm the installation of all required surface water control measures to prevent seed from washing away. • Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 per- cent tackifier. See BMP C121: Mulching for specifications. . Areas that will have seeding only and not landscaping may need compost or meal -based mulch included in the hydroseed in order to establish vegetation. Re -install native topsoil on the disturbed soil surface before application. See BMP T5.13: Post -Construction Soil Quality and Depth. • When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends up in contact with the soil surface. This reduces the ability to establish a good stand of grass quickly. To overcome this, consider increasing seed quantities by up to 50 percent. • Enhance vegetation establishment by dividing the hydromulch operation into two phases: Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift. Phase 2- Install the rest of the mulch and tackifier over the first lift. Or, enhance vegetation by: o Installing the mulch, seed, fertilizer, and tackifier in one lift. o Spread or blow straw over the top of the hydromulch at a rate of 800-1000 pounds per acre. Hold straw in place with a standard tackifier. Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost may be offset by the reduced need for: o Irrigation. Reapplication of mulch. Repair of failed slope surfaces. This technique works with standard hydromulch (1,500 pounds per acre minimum) and Bon- ded Fiber Matrix/ Mechanically Bonded Fiber Matrix (BFM/MBFMs) (3,000 pounds per acre minimum). . Seed may be installed by hand if: o Temporary and covered by straw, mulch, or topsoil. Permanent in small areas (usually less than 1 acre) and covered with mulch, topsoil, or erosion blankets. The seed mixes listed in Table II-3.4: Temporary and Permanent Seed Mixes include 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 285 75/195 recommended mixes for both temporary and permanent seeding. . Apply these mixes, with the exception of the wet area seed mix, at a rate of 120 pounds per acre. This rate can be reduced if soil amendments or slow -release fertilizers are used. Apply the wet area seed mix at a rate of 60 pounds per acre. Consult the local suppliers or the local conservation district for their recommendations. The appropriate mix depends on a variety of factors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used, depending on the soil type and hydrology of the area. Table 11-3.4: Temporary and Permanent Seed Mixes Common Name Latin Name % Weight % Purity % Germination Temporary Erosion Control Seed Mix A standard mix for areas requiring a temporary vegetative cover. Chewings or Festuca rubra var. annual bluegrass commutata or Poa 40 98 90 anna Perennial rye Lolium perenne 50 98 90 Redtop or colonial Agrostis alba or 5 92 85 bentgrass Agrostis tenuis White dutch clover Trifolium repens 5 98 90 Landscaping Seed Mix A recommended mix for landscaping seed. Perennial rye blend Lolium perenne 70 98 90 Chewings and red Festuca rubra var. fescue blend commutata or Fes- 30 98 90 tuca rubra Low -Growing Turf Seed Mix A turf seed mix for dry situations where there is no need for watering. This mix requires very little main- tenance. Dwarf tall fescue Festuca arundin- 45 98 90 (several varieties) acea var. Dwarf perennial Lolium perenne 30 98 90 rye (Barclay) var. barclay Red fescue Festuca rubra 20 98 90 Colonial bentgrass Agrostis tenuis 5 98 90 Bioswale Seed Mix A seed mix for bioswales and other intermittently wet areas. Tall or meadow fes- Festuca arundin- 75-80 98 90 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 286 76/195 Table II-3.4: Temporary and Permanent Seed Mixes (continued) Common Name Latin Name % Weight % Purity % Germination acea or Festuca cue elatior Seaside/Creeping Agrostis palustris 10-15 92 85 bentgrass Redtop bentgrass Agrostis alba or 5-10 90 80 Agrostis gigantea Wet Area Seed Mix A low -growing, relatively non-invasive seed mix appropriate forvery wet areas that are not regulated wet- lands. Consult Hydraulic Permit Authority (HPA) for seed mixes if applicable. Tall or meadow fes- Festuca arundin- acea or Festuca 60-70 98 90 cue elatior Seaside/Creeping Agrostis palustris 10-15 98 85 bentgrass Meadow foxtail Alepocurus praten- 10-15 90 80 sis Alsike clover Trifolium hybridum 1-6 98 90 Redtop bentgrass Agrostis alba 1-6 92 85 Meadow Seed Mix A recommended meadow seed mix for infrequently maintained areas or non -maintained areas where col- onization by native plants is desirable. Likely applications include rural road and utility right-of-way. Seed- ing should take place in September or very early October in order to obtain adequate establishment prior to the winter months. Consider the appropriateness of clover, a fairly invasive species, in the mix. Amending the soil can reduce the need for clover. Redtop or Oregon Agrostis alba or bentgrass Agrostis ore- 20 92 85 gonensis Red fescue Festuca rubra 70 98 90 White dutch clover Trifolium repens 10 98 90 Roughening and Rototilling The seedbed should be firm and rough. Roughen all soil no matter what the slope. Track walk slopes before seeding if engineering purposes require compaction. Backblading or smoothing of slopes greater than 4H:1 V is not allowed if they are to be seeded. Restoration -based landscape practices require deeper incorporation than that provided by a simple single -pass rototilling treatment. Wherever practical, initially rip the subgrade to improve long-term permeability, infiltration, and water inflow qualities. At a minimum, 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 287 77/195 permanent areas shall use soil amendments to achieve organic matter and permeability per- formance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches complete the rototilling process in multiple lifts, or prepare the engineered soil system per specifications and place to achieve the specified depth. Fertilizers • Conducting soil tests to determine the exact type and quantity of fertilizer is recommended. This will prevent the over -application of fertilizer. . Organic matter is the most appropriate form of fertilizer because it provides nutrients (includ- ing nitrogen, phosphorus, and potassium) in the least water-soluble form. . In general, use 10-4-6 N-P-K (nitrogen -phosphorus -potassium) fertilizer at a rate of 90 pounds per acre. Always use slow -release fertilizers because they are more efficient and have fewer environmental impacts. Do not add fertilizer to the hydromulch machine, or agit- ate, more than 20 minutes before use. Too much agitation destroys the slow -release coating. . There are numerous products available that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If 100 percent cottonseed meal is used as the mulch in hydroseed, chemical fertilizer may not be necessary. Cottonseed meal provides a good source of long-term, slow -release, available nitrogen. Bonded Fiber Matrix and Mechanically Bonded Fiber Matrix . On steep slopes use Bonded Fiber Matrix (BFM) or Mechanically Bonded Fiber Matrix (MBFM) products. Apply BFM/MBFM products at a minimum rate of 3,000 pounds per acre with approximately 10 percent tackifier. Achieve a minimum of 95 percent soil coverage during application. Numerous products are available commercially. Most products require 24-36 hours to cure before rainfall and cannot be installed on wet or saturated soils. Generally, products come in 40-50 pound bags and include all necessary ingredients except for seed and fertilizer. . Install products per manufacturer's instructions. • BFMs and MBFMs provide good alternatives to blankets in most areas requiring vegetation establishment. Advantages over blankets include: • BFM and MBFMs do not require surface preparation. • Helicopters can assist in installing BFM and MBFMs in remote areas. • On slopes steeper than 2.5H:1 V, blanket installers may require ropes and harnesses for safety. • Installing BFM and MBFMs can save at least $1,000 per acre compared to blankets. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 288 78/195 Maintenance Standards Reseed any seeded areas that fail to establish at least 75 percent cover (100 percent cover for areas that receive sheet or concentrated flows). If reseeding is ineffective, use an alternate method such as sodding, mulching, nets, or blankets. Reseed and protect by mulch any areas that experience erosion after achieving adequate cover. Reseed and protect by mulch any eroded area. Supply seeded areas with adequate moisture, but do not water to the extent that it causes run- off. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology's website at: https:Hecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 289 79/195 BMP C121: Mulching Purpose Mulching soils provides immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and moderating soil temperatures. There are a variety of mulches that can be used. This section discusses only the most common types of mulch. Conditions of Use As a temporary cover measure, mulch should be used: For less than 30 days on disturbed areas that require cover. . At all times for seeded areas, especially during the wet season and during the hot summer months. During the wet season on slopes steeper than 3H:1 V with more than 10 feet of vertical relief. Mulch may be applied at any time of the year and must be refreshed periodically. For seeded areas, mulch may be made up of 100 percent: . cottonseed meal; . fibers made of wood, recycled cellulose, hemp, or kenaf; 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 289 80/195 . compost; or blends of these. Tackifier shall be plant -based, such as guar or alpha plantago, or chemical -based such as poly- acrylamide or polymers. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. Recycled cellulose may contain polychlorinated biphenyl (PCBs). Ecology recommends that products should be evaluated for PCBs prior to use. Refer to BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection for conditions of use. PAM shall not be directly applied to water or allowed to enter a water body. Any mulch or tackifier product used shall be installed per the manufacturer's instructions. Design and Installation Specifications For mulch materials, application rates, and specifications, see Table II-3.6: Mulch Standards and Guidelines. Consult with the local supplier or the local conservation district for their recom- mendations. Increase the application rate until the ground is 95% covered (i.e. not visible under the mulch layer). Note: Thickness may be increased for disturbed areas in or near sensitive areas or other areas highly susceptible to erosion. Where the option of "Compost" is selected, it should be a coarse compost that meets the size grad- ations listed in Table 11-3.5: Size Gradations of Compost as Mulch Material when tested in accord- ance with Test Method 02.02-13 found in Test Methods for the Examination of Composting and Compost (Thompson, 2001). Table 11-3.5: Size Gradations of Compost as Mulch Material Sieve Size Percent Passing 3" 100% 1" 90% -100% 3/4" 70% -100% 1/4" 40% -100% Mulch used within the ordinary high-water mark of surface waters should be selected to minimize potential flotation of organic matter. Composted organic materials have higher specific gravities (densities) than straw, wood, or chipped material. Consult the Hydraulic Permit Authority (H PA) for mulch mixes if applicable. Maintenance Standards The thickness of the mulch cover must be maintained. Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remulched. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 290 81 /195 Table II-3.6: Mulch Standards and Guidelines Mulch Mater- Guideline Description ial Quality Standards Air-dried; free from undesirable seed and coarse material. Application 2"-3" thick; 5 bales per 1,000 sf or 2-3 tons per acre Rates Cost-effective protection when applied with adequate thickness. Hand - application generally requires greater thickness than blown straw. The Straw thickness of straw may be reduced by half when used in conjunction with seeding. In windy areas straw must be held in place by crimping, using a tackifier, or covering with netting. Blown straw always has to be held in Remarks place with a tackifier as even light winds will blow it away. Straw, however, has several deficiencies that should be considered when selecting mulch materials. It often introduces and/or encourages the propagation of weed species and it has no significant long-term benefits It should also not be used within the ordinary high-water elevation of surface waters (due to flot- ation). Quality No growth inhibiting factors. Standards Application Approx. 35-45 Ibs per 1,000 sf or 1,500 -2,000 Ibs per acre Hydromulch Rates Shall be applied with hydromulcher. Shall not be used without seed and Remarks tackifier unless the application rate is at least doubled. Fibers longer than about 3/4 -1 inch clog hydromulch equipment. Fibers should be kept to less than 3/4 inch. Quality No visible water or dust during handling. Must be produced per WAC 173- Standards 350, Solid Waste Handling Standards, but may have up to 35% biosolids. Application 2 thick min.; approx. 100 tons per acre (approx. 750 Ibs per cubic yard) Rates More effective control can be obtained by increasing thickness to 3". Excel - Compost lent mulch for protecting final grades until landscaping because it can be dir- ectly seeded or tilled into soil as an amendment. Compost used for mulch Remarks has a coarser size gradation than compost used for BMP C 125: Topsoiling / Composting or BMP T5.13: Post -Construction Soil Quality and Depth. It is more stable and practical to use in wet areas and during rainy weather conditions. Do not use near wetlands or near phosphorous impaired water bodies. Quality Gradations from fines to 6 inches in length for texture, variation, and inter - Chipped Standards locking properties. Include a mix of various sizes so that the average size Site Veget- is between 2- and 4- inches. ation Application Rates 2" thick min.; 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 291 82/195 Table II-3.6: Mulch Standards and Guidelines (continued) Mulch Mater- Guideline Description ial This is a cost-effective way to dispose of debris from clearing and grub- bing, and it eliminates the problems associated with burning. Generally, it should not be used on slopes above approx. 10% because of its tendency to be transported by runoff. It is not recommended within 200 feet of sur- Remarks face waters. If permanent seeding or planting is expected shortly after mulch, the decomposition of the chipped vegetation may tie up nutrients important to grass establishment. Note: thick application of this material over existing grass, herbaceous spe- cies, and some groundcovers could smother and kill vegetation. Quality No visible water or dust during handling. Must be purchased from a supplier Standards with a Solid Waste Handling Permit or one exempt from solid waste reg- ulations. Application 2 thick min.; approx. 100 tons per acre (approx. 750 lbs. per cubic yard) Wood- Rates Based This material is often called "wood straw" or "hog fuel". The use of mulch Mulch ultimately improves the organic matter in the soil. Special caution is Remarks advised regarding the source and composition of wood -based mulches. Its preparation typically does not provide any weed seed control, so evidence of residual vegetation in its composition or known inclusion of weed plants or seeds should be monitored and prevented (or minimized). Quality A blend of loose, long, thin wood pieces derived from native conifer or Standards deciduous trees with high length -to -width ratio. Application 2"thick min. Rates Wood Cost-effective protection when applied with adequate thickness. A min - Strand imum of 95-percent of the wood strand shall have lengths between 2 and Mulch 10-inches, with a width and thickness between 1/16 and 1/2-inches. The Remarks mulch shall not contain resin, tannin, or other compounds in quantities that would be detrimental to plant life. Sawdust or wood shavings shall not be used as mulch. [Specification 9-14.4(4) from the Standard Specifications for Road, Bridge, and Municipal Construction (WSDOT, 2016) 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 292 83/195 BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 292 84/195 Nets (commonly called matting) are strands of material woven into an open, but high -tensile strength net (for example, coconut fiber matting). Blankets are strands of material that are not tightly woven, but instead form a layer of interlocking fibers, typically held together by a biodegradable or pho- todegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets, but cover the ground more completely. Coir (coconut fiber) fabric comes as both nets and blankets. Conditions of Use Erosion control netting and blankets shall be made of natural plant fibers unaltered by synthetic materials. Erosion control nets and blankets should be used: . To aid permanent vegetated stabilization of slopes 2H:1 V or greater and with more than 10 feet of vertical relief. For drainage ditches and swales (highly recommended). The application of appropriate net- ting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due to their open, porous structure. Nets and blankets can be used to permanently stabilize channels and may provide a cost-effective, environmentally preferable alternative to riprap. Disadvantages of nets and blankets include: . Surface preparation is required. . On slopes steeper than 2.5H:1 V, net and blanket installers may need to be roped and har- nessed for safety. . They cost at least $4,000-6,000 per acre installed. Advantages of nets and blankets include: . Installation without mobilizing special equipment. . Installation by anyone with minimal training . Installation in stages or phases as the project progresses. . Installers can hand place seed and fertilizer as they progress down the slope. . Installation in any weather. . There are numerous types of nets and blankets that can be designed with various parameters in mind. Those parameters include: fiber blend, mesh strength, longevity, biodegradability, cost, and availability. An alternative to nets and blankets in some limited conditions is BMP C202: Riprap Channel Lining. Ensure that BMP C202: Riprap Channel Lining is appropriate before using it as a substitute for nets and blankets. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 293 85/195 Design and Installation Specifications See Figure II-3.3: Channel Installation (Clackamas County et al., 2008) and Figure II-3.4: Slope Installation for typical orientation and installation of nets and blankets used in channels and as slope protection. Note: these are typical only; all nets and blankets must be installed per manufacturer's installation instructions. . Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. . Installation of nets and blankets on slopes: 1. Complete final grade and track walk up and down the slope. 2. Install hydromulch with seed and fertilizer. 3. Dig a small trench, approximately 12 inches wide by 6 inches deep along the top of the slope. 4. Install the leading edge of the net/blanket into the small trench and staple approximately every 18 inches. NOTE: Staples are metal, "U"-shaped, and a minimum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. 5. Roll the net/blanket slowly down the slope as the installer walks backward. NOTE: The net/blanket rests against the installer's legs. Staples are installed as the net/blanket is unrolled. It is critical that the proper staple pattern is used for the net/blanket being installed. The net/blanket is not to be allowed to roll down the slope on its own as this stretches the net/blanket, making it impossible to maintain soil contact. In addition, no one is allowed to walk on the net/blanket after it is in place. 6. If the net/blanket is not long enough to cover the entire slope length, the trailing edge of the upper net/blanket should overlap the leading edge of the lower net/blanket and be stapled. On steeper slopes, this overlap should be installed in a small trench, stapled, and covered with soil. • With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the designer consult the manufacturer's inform- ation and that a site visit takes place in order to ensure that the product specified is appro- priate. Information is also available in WSDOT's Standard Specifications for Road, Bridge, and Municipal Construction Division 8-01 and Division 9-14 (WSDOT, 2016). • Usejute matting in conjunction with mulch (BMP C121: Mulching). Excelsior, woven straw blankets and coir (coconut fiber) blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in cer- tain circumstances. • In general, most nets (e.g., jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. • Extremely steep, unstable, wet, or rocky slopes are often appropriate candidates for use of synthetic blankets, as are riverbanks, beaches and other high-energy environments. If 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 294 86/195 synthetic blankets are used, the soil should be hydromulched first. 100-percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or fiber mesh and stitching which may last up to a year. Most netting used with blankets is photodegradable, meaning it breaks down under sunlight (not UV stabilized). However, this process can take months or years even under bright sun. Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to finc non -degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition, birds and small animals can become trapped in the netting. Maintenance Standards . Maintain good contact with the ground. Erosion must not occur beneath the net or blanket. Repair and staple any areas of the net or blanket that are damaged or not in close contact with the ground. . Fix and protect eroded areas if erosion occurs due to poorly controlled drainage. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 295 87/195 Figure II-3.4: Slope Installation Notes: 1. Slope surface shall be smooth before placement for proper soil contact. 2. Stapling pattern as per manufacturers recommendations. 3. Do not stretch blankets/mattings tight - allow the rolls to mold to any irregularities. 4. For slopes less than 3HAV, rolls may be placed in horizontal strips. 5. If there is a berm at the top of the slope, anchor upslope of the berm. 6. Lime, fertilize, and seed before installation. Planting of shrubs, trees, etc. should occur after installation. DEPARTMENT OF ECOLOGY State of Washington area, turn the end under 4" and staple at 12" intervals Slope Installation NOT TO SCALE Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 297 88/195 BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Use Plastic covering may be used on disturbed areas that require cover measures for less than 30 days, except as stated below. • Plastic is particularly useful for protecting cut and fill slopes and stockpiles. However, the rel- atively rapid breakdown of most polyethylene sheeting makes it unsuitable for applications greater than six months. • Due to rapid runoff caused by plastic covering, do not use this method upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. • Plastic sheeting may result in increased runoff volumes and velocities, requiring additional on - site measures to counteract the increases. Creating a trough with wattles or other material can convey clean water away from these areas. . To prevent undercutting, trench and backfill rolled plastic covering products. . Although the plastic material is inexpensive to purchase, the cost of installation, maintenance, removal, and disposal add to the total costs of this BMP. • Whenever plastic is used to protect slopes, install water collection measures at the base of the slope. These measures include plastic -covered berms, channels, and pipes used to convey clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a plastic covered slope with dirty runoff from a project. . Other uses for plastic include: • Temporary ditch liner. • Pond liner in temporary sediment pond. • Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored. • Emergency slope protection during heavy rains. • Temporary drainpipe ("elephant trunk") used to direct water. Design and Installation Specifications Plastic slope cover must be installed as follows: 1. Run plastic up and down the slope, not across the slope. 2. Plastic maybe installed perpendicular to a slope if the slope length is less than 10 feet. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 298 89/195 3. Provide a minimum of 8-inch overlap at the seams. 4. On long or wide slopes, or slopes subject to wind, tape all seams. 5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath. 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and tie them together with twine to hold them in place. 7. Inspect plastic for rips, tears, and open seams regularly and repair immediately. This prevents high velocity runoff from contacting bare soil, which causes extreme erosion. 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. • Plastic sheeting shall have a minimum thickness of 0.06 millimeters. . If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. Maintenance Standards . Torn sheets must be replaced and open seams repaired. • Completely remove and replace the plastic if it begins to deteriorate due to ultraviolet radi- ation. • Completely remove plastic when no longer needed. • Dispose of old tires used to weight down plastic sheeting appropriately. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology's website at: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 299 90/195 BMP C150: Materials on Hand Purpose Keep quantities of erosion prevention and sediment control materials on the project site at all times to be used for regular maintenance and emergency situations such as unexpected heavy rains. Hav- ing these materials on -site reduces the time needed to replace existing or implement new BMPs when inspections indicate that existing BMPs are not meeting the Construction SWPPP require- ments. In addition, contractors can save money by buying some materials in bulk and storing them at their office or yard. Conditions of Use . Construction projects of any size or type can benefit from having materials on hand. A small commercial development project could have a roll of plastic and some gravel available for immediate protection of bare soil and temporary berm construction. A large earthwork project, such as highway construction, might have several tons of straw, several rolls of plastic, flexible 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 314 91 /195 pipe, sandbags, geotextile fabric and steel "T" posts. . Materials should be stockpiled and readily available before any site clearing, grubbing, or earthwork begins. A large contractor or project proponent could keep a stockpile of materials that are available for use on several projects. . If storage space at the project site is at a premium, the contractor could maintain the materials at their office or yard. The office or yard must be less than an hour from the project site. Design and Installation Specifications Depending on project type, size, complexity, and length, materials and quantities will vary. A good minimum list of items that will cover numerous situations includes: . Clear Plastic, 6 mil • Drainpipe, 6 or 8 inch diameter • Sandbags, filled . Straw Bales for mulching • Quarry Spalls • Washed Gravel . Geotextile Fabric . Catch Basin Inserts . Steel "T" Posts . Silt fence material • Straw Wattles Maintenance Standards . All materials with the exception of the quarry spalls, steel "T" posts, and gravel should be kept covered and out of both sun and rain. • Re -stock materials as needed. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 315 92/195 BMP C151: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. Concrete spillage or concrete dis- charge to waters of the State is prohibited. Use this BMP to minimize and eliminate concrete, con- crete process water, and concrete slurry from entering waters of the State. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 315 93/195 Conditions of Use Any time concrete is used, utilize these management practices. Concrete construction project com- ponents include, but are not limited to: • Curbs . Sidewalks • Roads • Bridges • Foundations • Floors • Runways Disposal options for concrete, in order of preference are: 1. Off -site disposal 2. Concrete wash -out areas (see BMP C154: Concrete Washout Area) 3. De minimus washout to formed areas awaiting concrete Design and Installation Specifications Wash concrete truck drums at an approved off -site location or in designated concrete washout areas only. Do not wash out concrete trucks onto the ground (including formed areas awaiting concrete), or into storm drains, open ditches, streets, or streams. Refer to BMP_ C 154: Concrete Washout Area for information on concrete washout areas. Return unused concrete remaining in the truck and pump to the originating batch plant for recycling. Do not dump excess concrete on site, except in designated concrete washout areas as allowed in BMP C154: Concrete Washout Area. • Wash small concrete handling equipment (e.g. hand tools, screeds, shovels, rakes, floats, trowels, and wheelbarrows) into designated concrete washout areas or into formed areas awaiting concrete pour. . At no time shall concrete be washed off into the footprint of an area where an infiltration fea- ture will be installed. • Wash equipment difficult to move, such as concrete paving machines, in areas that do not dir- ectly drain to natural or constructed stormwater conveyance or potential infiltration areas. • Do not allow washwater from areas, such as concrete aggregate driveways, to drain directly (without detention or treatment) to natural or constructed stormwater conveyances. • Contain washwater and leftover product in a lined container when no designated concrete washout areas (or formed areas, allowed as described above) are available. Dispose of con- tained concrete and concrete washwater (process water) properly. 2019 Stormwater Management Manual for Western Washington Volume ll - Chapter 3 - Page 316 94/195 Always use forms or solid barriers for concrete pours, such as pilings, within 15-feet of surface waters. Refer to BMP C252: Treating and Disposing of High pH Water for pH adjustment require- ments. Refer to the Construction Stormwater General Permit (CSWGP) for pH monitoring require- ments if the project involves one of the following activities: Significant concrete work (as defined in the CSWGP) The use of soils amended with (but not limited to) Portland cement -treated base, cement kiln dust or fly ash. Discharging stormwater to segments of water bodies on the 303(d) list (Category 5) for high pH. Maintenance Standards Check containers for holes in the liner daily during concrete pours and repair the same day. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 317 95/195 BMP C152: Sawcutting and Surfacing Pollution Prevention Purpose Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting), both of which can violate the water quality standards in the receiving water. Concrete spillage or concrete discharge to waters of the State is prohibited. Use this BMP to minimize and eliminate process water and slurry created through sawcutting or surfacing from enter- ing waters of the State. Conditions of Use Utilize these management practices anytime sawcutting or surfacing operations take place. Saw - cutting and surfacing operations include, but are not limited to: • Sawing • Coring • Grinding . Roughening • Hydro -demolition • Bridge and road surfacing 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 317 96/195 Design and Installation Specifications . Vacuum slurry and cuttings during cutting and surfacing operations. . Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight. . Slurry and cuttings shall not drain to any natural or constructed drainage conveyance includ- ing stormwater systems. This may require temporarily blocking catch basins. • Dispose of collected slurry and cuttings in a manner that does not violate ground water or sur- face water quality standards. • Do not allow process water generated during hydro -demolition, surface roughening or similar operations to drain to any natural or constructed drainage conveyance including stormwater systems. Dispose of process water in a manner that does not violate ground water or surface water quality standards. • Handle and dispose of cleaning waste material and demolition debris in a manner that does not cause contamination of water. Dispose of sweeping material from a pick-up sweeper at an appropriate disposal site. Maintenance Standards Continually monitor operations to determine whether slurry, cuttings, or process water could enter waters of the state. If inspections show that a violation of water quality standards could occur, stop operations and immediately implement preventive measures such as berms, barriers, secondary containment, and/or vacuum trucks. 2019 Stormwater Management Manual for Western Washington Volume // - Chapter 3 - Page 318 97/195 BMP C153: Material Delivery, Storage, and Containment Purpose Prevent, reduce, or eliminate the discharge of pollutants to the stormwater system or watercourses from material delivery and storage. Minimize the storage of hazardous materials on -site, store mater- ials in a designated area, and install secondary containment. Conditions of Use Use at construction sites with delivery and storage of the following materials: • Petroleum products such as fuel, oil and grease . Soil stabilizers and binders (e.g., Polyacrylamide) • Fertilizers, pesticides and herbicides . Detergents . Asphalt and concrete compounds 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 318 98/195 • Hazardous chemicals such as acids, lime, adhesives, paints, solvents, and curing compounds . Any other material that maybe detrimental if released to the environment Design and Installation Specifications . The temporary storage area should be located away from vehicular traffic, near the con- struction entrance(s), and away from waterways or storm drains. . Safety Data Sheets (SDS) should be supplied for all materials stored. Chemicals should be kept in their original labeled containers. • Hazardous material storage on -site should be minimized. • Hazardous materials should be handled as infrequently as possible. • During the wet weather season (Oct 1 — April 30), consider storing materials in a covered area. • Materials should be stored in secondary containments, such as an earthen dike, horse trough, or even a children's wading pool for non -reactive materials such as detergents, oil, grease, and paints. Small amounts of material may be secondarily contained in "bus boy" trays or con- crete mixing trays. • Do not store chemicals, drums, or bagged materials directly on the ground. Place these items on a pallet and, when possible, within secondary containment. . If drums must be kept uncovered, store them at a slight angle to reduce ponding of rainwater on the lids to reduce corrosion. Domed plastic covers are inexpensive and snap to the top of drums, preventing water from collecting. • Liquids, petroleum products, and substances listed in 40 CFR Parts 110, 117, or 302 shall be stored in approved containers and drums and shall not be overfilled. Containers and drums shall be stored in temporary secondary containment facilities. . Temporary secondary containment facilities shall provide for a spill containment volume able to contain 10% of the total enclosed container volume of all containers, or 110% of the capa- city of the largest container within its boundary, whichever is greater. • Secondary containment facilities shall be impervious to the materials stored therein for a min- imum contact time of 72 hours. • Sufficient separation should be provided between stored containers to allow for spill cleanup and emergency response access. • During the wet weather season (Oct 1 — April 30), each secondary containment facility shall be covered during non -working days, prior to and during rain events. . Keep material storage areas clean, organized and equipped with an ample supply of appro- priate spill clean-up material (spill kit). . The spill kit should include, at a minimum: 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 319 99/195 1-Water Resistant Nylon Bag 3-Oil Absorbent Socks 3"x 4' 2-Oil Absorbent Socks 3" x 10' 0 12-Oil Absorbent Pads 17"xl 9" 1-Pair Splash Resistant Goggles o 3-Pair Nitrile Gloves 10-Disposable Bags with Ties Instructions Maintenance Standards . Secondary containment facilities shall be maintained free of accumulated rainwater and spills. In the event of spills or leaks, accumulated rainwater and spills shall be collected and placed into drums. These liquids shall be handled as hazardous waste unless testing determines them to be non -hazardous. • Re -stock spill kit materials as needed. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 320 100/195 BMP C154: Concrete Washout Area Purpose Prevent or reduce the discharge of pollutants from concrete waste to stormwater by conducting washout off -site, or performing on -site washout in a designated area. Conditions of Use Concrete washout areas are implemented on construction projects where: • Concrete is used as a construction material . It is not possible to dispose of all concrete wastewater and washout off -site (ready mix plant, etc.). • Concrete truck drums are washed on -site. Note that auxiliary concrete truck components (e.g. chutes and hoses) and small concrete handling equipment (e.g. hand tools, screeds, shovels, rakes, floats, trowels, and wheel- barrows) may be washed into formed areas awaiting concrete pour. At no time shall concrete be washed off into the footprint of an area where an infiltration feature will be installed. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 320 101/195 Design and Installation Specifications Implementation • Perform washout of concrete truck drums at an approved off -site location or in designated con- crete washout areas only. • Do not wash out concrete onto non -formed areas, or into storm drains, open ditches, streets, or streams. • Wash equipment difficult to move, such as concrete paving machines, in areas that do not dir- ectly drain to natural or constructed stormwater conveyance or potential infiltration areas. • Do not allow excess concrete to be dumped on -site, except in designated concrete washout areas as allowed above. • Concrete washout areas may be prefabricated concrete washout containers, or self -installed structures (above -grade or below -grade). • Prefabricated containers are most resistant to damage and protect against spills and leaks. Companies may offer delivery service and provide regular maintenance and disposal of solid and liquid waste. . If self -installed concrete washout areas are used, below -grade structures are preferred over above -grade structures because they are less prone to spills and leaks. . Self -installed above -grade structures should only be used if excavation is not practical. • Concrete washout areas shall be constructed and maintained in sufficient quantity and size to contain all liquid and concrete waste generated by washout operations. Education • Discuss the concrete management techniques described in this BMP with the ready -mix con- crete supplier before any deliveries are made. • Educate employees and subcontractors on the concrete waste management techniques described in this BMP. . Arrange for the contractor's superintendent or Certified Erosion and Sediment Control Lead (CESCL) to oversee and enforce concrete waste management procedures. . A sign should be installed adjacent to each concrete washout area to inform concrete equip- ment operators to utilize the proper facilities. Contracts Incorporate requirements for concrete waste management into concrete supplier and subcontractor agreements. 2019 Stormwater Management Manual for Western Washington Volume ll - Chapter 3 - Page 321 102/195 Location and Placement • Locate concrete washout areas at least 50 feet from sensitive areas such as storm drains, open ditches, water bodies, or wetlands. . Allow convenient access to the concrete washout area for concrete trucks, preferably near the area where the concrete is being poured. . If trucks need to leave a paved area to access the concrete washout area, prevent track -out with a pad of rock or quarry spalls (see BMP C105: Stabilized Construction Access). These areas should be far enough away from other construction traffic to reduce the likelihood of acci- dental damage and spills. . The number of concrete washout areas you install should depend on the expected demand for storage capacity. . On large sites with extensive concrete work, concrete washout areas should be placed in mul- tiple locations for ease of use by concrete truck drivers. Concrete Truck Washout Procedures Washout of concrete truck drums shall be performed in designated concrete washout areas only. Concrete washout from concrete pumper bins can be washed into concrete pumper trucks and discharged into designated concrete washout areas or properly disposed of off -site. Concrete Washout Area Installation • Concrete washout areas should be constructed as shown in the figures below, with a recom- mended minimum length and minimum width of 10 ft, but with sufficient quantity and volume to contain all liquid and concrete waste generated by washout operations. • Plastic lining material should be a minimum of 10 mil polyethylene sheeting and should be free of holes, tears, or other defects that compromise the impermeability of the material. • Lath and flagging should be commercial type. • Liner seams shall be installed in accordance with manufacturers' recommendations. • Soil base shall be prepared free of rocks or other debris that may cause tears or holes in the plastic lining material. Maintenance Standards Inspection and Maintenance . Inspect and verify that concrete washout areas are in place prior to the commencement of con- crete work. . Once concrete wastes are washed into the designated washout area and allowed to harden, 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 322 103/195 the concrete should be broken up, removed, and disposed of per applicable solid waste reg- ulations. Dispose of hardened concrete on a regular basis. • During periods of concrete work, inspect the concrete washout areas daily to verify continued performance. • Check overall condition and performance. • Check remaining capacity (% full). • If using self -installed concrete washout areas, verify plastic liners are intact and side - walls are not damaged. • If using prefabricated containers, check for leaks. • Maintain the concrete washout areas to provide adequate holding capacity with a minimum freeboard of 12 inches. • Concrete washout areas must be cleaned, or new concrete washout areas must be con- structed and ready for use once the concrete washout area is 75% full. If the concrete washout area is nearing capacity, vacuum and dispose of the waste material in an approved manner. • Do not discharge liquid or slurry to waterways, storm drains or directly onto ground. • Do not discharge to the sanitary sewer without local approval. • Place a secure, non -collapsing, non -water collecting cover over the concrete washout area prior to predicted wet weather to prevent accumulation and overflow of pre- cipitation. • Remove and dispose of hardened concrete and return the structure to a functional con- dition. Concrete may be reused on -site or hauled away for disposal or recycling. When you remove materials from a self -installed concrete washout area, build a new struc- ture; or, if the previous structure is still intact, inspect for signs of weakening or damage, and make any necessary repairs. Re -line the structure with new plastic after each cleaning. Removal of Concrete Washout Areas • When concrete washout areas are no longer required for the work, the hardened concrete, slurries and liquids shall be removed and properly disposed of. • Materials used to construct concrete washout areas shall be removed from the site of the work and disposed of or recycled. Holes, depressions or other ground disturbance caused by the removal of the concrete washout areas shall be backfilled, repaired, and stabilized to prevent erosion. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 323 104/195 Figure II-3.7: Concrete Washout Area with Wood Planks Plan Lath and flagging on 3 sides Sandbag 3erm 10 mil plastic lining 0 1m ,r %• '' Berm Section A -A lining Type "Below Grade" Stake (typ.) iil plastic lining Sandbag '1 Actual layout determined in the field. 2. A concrete washout sign shall be installed within 10 m of the temporary concrete washout facility. Wood frame securely fastened around entire perimeter with two stakes 10 mil plastic lining Section B-B 2x12 rough Plan wood frame Tvae "Above Grade" with Wood Planks NOT TO SCALE Concrete Washout Area with Wood Planks Revised June 2016 DEPARTMENT OF ECOLOGYplease see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 324 105/195 Figure II-3.8: Concrete Washout Area with Straw Bales Straw bale astic lining Binding wire Staples material (2 per bale) L'ol) Wood or Plywood metal stakes 1200 mm x 610 mm Wood post (2 per bale) painted white (89 mm x 89 mm Lag screws x 2.4 m) Section B-B r. (12.5 mm) iCONCRETEi I Black letters WASHOUT , 1 l o 150 mm height 915 mm 1 3m Minimum Stake (typ) B� Varies ■ Straw bale J (typ•) DEPARTMENT OF ECOLOGY State of Washington Plan tIu u 915 mm Concrete Washout Sign Detail (or equivalent) �B 50 mm 200 mm �` 3.05 mm dia. steel wire Staple Detail 10 mil plastic lining Notes: 1. Actual layout determined in the field. 2. The concrete washout sign shall be installed within 10 m of the temporary concrete washout facility. Type "Above Grade" with Straw Bales NOT TO SCALE Concrete Washout Area with Straw Bales Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 325 106/195 Figure 11-3.9: Prefabricated Concrete Washout Container w/Ramp DEPARTMENT OF ECOLOGY State of Washington NOT TO SCALE Prefabricated Concrete Washout Container w/Ramp Revised June 2016 Please see http.1Avww.ecy.wa.gov/copynght html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 326 107/195 BMP C160: Certified Erosion and Sediment Control Lead Purpose The project proponent designates at least one person as the responsible representative in charge of erosion and sediment control (ESC), and water quality protection. The designated person shall be responsible for ensuring compliance with all local, state, and federal erosion and sediment control and water quality requirements. Construction sites one acre or larger that discharge to waters of the State must designate a Certified Erosion and Sediment Control Lead (CESCL) as the responsible representative. Conditions of Use A CESCL shall be made available on projects one acre or larger that discharge stormwater to sur- face waters of the state. Sites less than one acre may have a person without CESCL certification conduct inspections. The CESCL shall: Have a current certificate proving attendance in an erosion and sediment control training course that meets the minimum ESC training and certification requirements established by Ecology. Ecology has provided the minimum requirements for CESCL course training, as well as a list of ESC training and certification providers at: https:Hecology.wa.gov/Regulations-Permits/Permits-certifications/Certified-erosion-sed- iment-control K7 Be a Certified Professional in Erosion and Sediment Control (CPESC). For additional inform- ation go to: http://www.envirocertintl.org/cpesc/ Specifications . CESCL certification shall remain valid for three years. . The CESCL shall have authority to act on behalf of the contractor or project proponent and shall be available, or on -call, 24 hours per day throughout the period of construction. . The Construction SWPPP shall include the name, telephone number, fax number, and address of the designated CESCL. See II-2 Construction Stormwater Pollution Prevention Plans (Construction SWPPPs . A CESCL may provide inspection and compliance services for multiple construction projects in the same geographic region, but must be on site whenever earthwork activities are 2019 Stormwater Management Manual for Western Washington Volume // - Chapter 3 - Page 327 108/195 occurring that could generate release of turbid water. Duties and responsibilities of the CESCL shall include, but are not limited to the following: • Maintaining a permit file on site at all times which includes the Construction SWPPP and any associated permits and plans. • Directing BMP installation, inspection, maintenance, modification, and removal. • Updating all project drawings and the Construction SWPPP with changes made. • Completing any sampling requirements including reporting results using electronic Dis- charge Monitoring Reports (WebDMR). • Facilitate, participate in, and take corrective actions resulting from inspections per- formed by outside agencies or the owner. • Keeping daily logs, and inspection reports. Inspection reports should include: ■ Inspection date/time. ■ Weather information; general conditions during inspection and approximate amount of precipitation since the last inspection. ■ Visual monitoring results, including a description of discharged stormwater. The presence of suspended sediment, turbid water, discoloration, and oil sheen shall be noted, as applicable. ■ Any water quality monitoring performed during inspection. ■ General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. ■ A summary or list of all BMPs implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted: 1. Locations of BMPs inspected. 2. Locations of BMPs that need maintenance. 3. Locations of BMPs that failed to operate as designed or intended. 4. Locations of where additional or different BMPs are required. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 328 109/195 BMP C162: Scheduling Purpose Sequencing a construction project reduces the amount and duration of soil exposed to erosion by wind, rain, runoff, and vehicle tracking. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 328 110/195 Conditions of Use The construction sequence schedule is an orderly listing of all major land -disturbing activities together with the necessary erosion and sedimentation control measures planned for the project. This type of schedule guides the contractor on work to be done before other work is started so that serious erosion and sedimentation problems can be avoided. Following a specified work schedule that coordinates the timing of land -disturbing activities and the installation of control measures is perhaps the most cost-effective way of controlling erosion during construction. The removal of ground cover leaves a site vulnerable to erosion. Construction sequen- cing that limits land clearing, provides timely installation of erosion and sedimentation controls, and restores protective cover quickly can significantly reduce the erosion potential of a site. Design Considerations . Minimize construction during rainy periods. Schedule projects to disturb only small portions of the site at any one time. Complete grading as soon as possible. Immediately stabilize the disturbed portion before grading the next por- tion. Practice staged seeding in order to revegetate cut and fill slopes as the work progresses. II-3.3 Construction Runoff BMPs 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 329 111/195 Maintenance Standards Replace riprap as needed. BMP C203: Water Bars Purpose A water bar is a small ditch or ridge of material that is constructed diagonally across a road or right- of-way to divert stormwater runoff from the road surface, wheel tracks, or a shallow road ditch. See Figure II-3.12: Water Bar. Conditions of Use Clearing right-of-way and construction of access for power lines, pipelines, and other similar install- ations often require long narrow right-of-ways over sloping terrain. Disturbance and compaction pro- motes gully formation in these cleared strips by increasing the volume and velocity of runoff. Gully formation may be especially severe in tire tracks and ruts. To prevent gullying, runoff can often be diverted across the width of the right-of-way to undisturbed areas by using small predesigned diver- sions. Give special consideration to each individual outlet area, as well as to the cumulative effect of added diversions. Use gravel to stabilize the diversion where significant vehicular traffic is anticipated. Design and Installation Specifications . Height: 8-inch minimum, measured from the channel bottom to the ridge top. . Side slope of channel: 2H:1 V maximum; 3H:1 V or flatter when vehicles will cross. . Top width of ridge: 6-inch minimum. Locate water bars to use natural drainage systems and to discharge into well vegetated stable areas. . See Table II-3.9: Water Bar Spacing Guidelines: Table II-3.9: Water Bar Spacing Guidelines Slope Along Road (%) Spacing (ft) < 5 125 5-10 100 10 - 20 75 20 - 35 50 > 35 Use rock lined ditch 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 338 112/195 . Grade of water bar and angle: Select an angle that results in a ditch slope less than 2 percent. . Install the water bar as soon as the clearing and grading is complete. When utilities are being installed, reconstruct the water bar as construction is complete in each section. . Compact the water bar ridge. . Stabilize, seed, and mulch the portions that are not subject to traffic. Gravel the areas crossed by vehicles. . Note that BMP C208: Triangular Silt Dike (TSD) can be used to create the ridge for the water bar. Maintenance Standards Periodically inspect water bars after every heavy rainfall for wear and erosion damage. . Immediately remove sediment from the flow area and repair the dike. . Check outlet areas and make timely repairs as needed. When permanent road drainage is established and the area above the temporary water bar is permanently stabilized, remove the dikes and fill the channel to blend with the natural ground, and appropriately stabilize the disturbed area. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 339 113/195 Figure II-3.12: Water Bar Q'own9 5\0Pe — DEPARTMENT OF ECOLOGY State of Washington Use material excavated from dip to construct hump 6" min. I r / RoaO's 417'aoe Water Bar NOT TO SCALE Revised July 2017 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 340 114/195 BMP C207: Check Dams Purpose Construction of check dams across a swale or ditch reduces the velocity of concentrated flow and dis- sipates energy at the check dam. Conditions of Use Use check dams where temporary or permanent channels are not yet vegetated, channel lining is infeasible, and/or velocity checks are required. . Check dams may not be placed in streams unless approved by the State Department of Fish and Wildlife. . Check dams may not be placed in wetlands without approval from a permitting agency. • Do not place check dams below the expected backwater from any salmonid bearing water between October 1 and May 31 to ensure that there is no loss of high flow refuge habitat for overwintering juvenile salmonids and emergent salmonid fry. Design and Installation Specifications • Construct rock check dams from appropriately sized rock. The rock used must be large enough to stay in place given the expected design flow through the channel. The rock must be placed by hand or by mechanical means (do not dump the rock to form the dam) to achieve complete coverage of the ditch or swale and to ensure that the center of the dam is lower than the edges. . Check dams may also be constructed of either rock or pea -gravel filled bags. Numerous new products are also available for this purpose. They tend to be re -usable, quick and easy to install, effective, and cost efficient. • Place check dams perpendicular to the flow of water. . The check dam should form a triangle when viewed from the side. This prevents undercutting as water flows over the face of the check dam rather than falling directly onto the ditch bottom. • Before installing check dams, impound and bypass upstream water flow away from the work area. Options for bypassing include pumps, siphons, or temporary channels. . Check dams combined with sumps work more effectively at slowing flow and retaining sed- iment than a check dam alone. A deep sump should be provided immediately upstream of the check dam. . In some cases, if carefully located and designed, check dams can remain as permanent install- ations with very minor regrading. They may be left as either spillways, in which case accu- mulated sediment would be graded and seeded, or as check dams to prevent further sediment from leaving the site. . The maximum spacing between check dams shall be such that the downstream toe of the 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 351 115/195 upstream dam is at the same elevation as the top of the downstream dam. • Keep the maximum height at 2 feet at the center of the check dam. • Keep the center of the check dam at least 12 inches lower than the outer edges at natural ground elevation. • Keep the side slopes of the check dam at 2H:1 V or flatter. . Key the stone into the ditch banks and extend it beyond the abutments a minimum of 18 inches to avoid washouts from overflow around the dam. • Use filter fabric foundation under a rock or sand bag check dam. If a blanket ditch liner is used, filter fabric is not necessary. A piece of organic or synthetic blanket cut to fit will also work for this purpose. . In the case of grass -lined ditches and swales, all check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale - unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • Ensure that channel appurtenances, such as culvert entrances below check dams, are not subject to damage or blockage from displaced stones. . See Figure II-3.16: Rock Check Dam. Maintenance Standards Check dams shall be monitored for performance and sediment accumulation during and after each rainfall that produces runoff. Sediment shall be removed when it reaches one half the sump depth. . Anticipate submergence and deposition above the check dam and erosion from high flows around the edges of the dam. . If significant erosion occurs between dams, install a protective riprap liner in that portion of the channel. See BMP C202: Riprap Channel Lining. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology's website at: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 352 116/195 Figure 11-3.16: Rock Check Dam View Looking Upstream A 18" 12" (0.5m) (150mm) (0.6m) Note: Key stone into channel banks and extend it beyond the abutments a minimum of 18" (0.5m) to prevent flow around dam. A Section A -A j Spacing Between Check Dams DEPARTMENT OF ECOLOGY State of Washington 'L' = the distance such that points 'A' and 'B' are of equal elevation. Rock Check Dam NOT TO SCALE Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 353 117/195 BMP C209: Outlet Protection Purpose Outlet protection prevents scour at conveyance outlets and minimizes the potential for downstream erosion by reducing the velocity of concentrated stormwater flows. Conditions of Use Use outlet protection at the outlets of all ponds, pipes, ditches, or other conveyances that discharge to a natural or manmade drainage feature such as a stream, wetland, lake, or ditch. Design and Installation Specifications . The receiving channel at the outlet of a pipe shall be protected from erosion by lining a min- imum of 6 feet downstream and extending up the channel sides a minimum of 1—foot above the maximum tailwater elevation, or 1-foot above the crown, whichever is higher. For pipes lar- ger than 18 inches in diameter, the outlet protection lining of the channel shall be four times the diameter of the outlet pipe. • Standard wingwalls, tapered outlets, and paved channels should also be considered when appropriate for permanent culvert outlet protection (WSDOT, 2015). • BMP C122: Nets and Blankets or BMP C202: Riprap Channel Lining provide suitable options for lining materials. • With low flows, BMP C201: Grass -Lined Channels can be an effective alternative for lining material. . The following guidelines shall be used for outlet protection with riprap: If the discharge velocity at the outlet is less than 5 fps, use 2-inch to 8-inch riprap. Min- imum thickness is 1-foot. For 5 to 10 fps discharge velocity at the outlet, use 24-inch to 48-inch riprap. Minimum 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 355 118/195 thickness is 2 feet. For outlets at the base of steep slope pipes (pipe slope greater than 10 percent), use an engineered energy dissipator. Filter fabric or erosion control blankets should always be used under riprap to prevent scour and channel erosion. See BMP C122: Nets and Blankets. Bank stabilization, bioengineering, and habitat features maybe required for disturbed areas. This work may require a Hydraulic Project Approval (HPA) from the Washington State Depart- ment of Fish and Wildlife. See 1-2.11 Hydraulic Project Approvals. Maintenance Standards . Inspect and repair as needed. . Add rock as needed to maintain the intended function. . Clean energy dissipator if sediment builds up. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 356 119/195 BMP C220: Inlet Protection Purpose Inlet protection prevents coarse sediment from entering drainage systems prior to permanent sta- bilization of the disturbed area. Conditions of Use Use inlet protection at inlets that are operational before permanent stabilization of the disturbed areas that contribute runoff to the inlet. Provide protection for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless those inlets are preceded by a sediment trapping BMP. Also consider inlet protection for lawn and yard drains on new home construction. These small and numerous drains coupled with lack of gutters can add significant amounts of sediment into the roof drain system. If possible, delay installing lawn and yard drains until just before landscaping, or cap these drains to prevent sediment from entering the system until completion of landscaping. Provide 18-inches of sod around each finished lawn and yard drain. Table II-3.10: Storm Drain Inlet Protection lists several options for inlet protection. All of the methods for inlet protection tend to plug and require a high frequency of maintenance. Limit contributing drain- age areas for an individual inlet to one acre or less. If possible, provide emergency overflows with additional end -of -pipe treatment where stormwater ponding would cause a hazard. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 356 120/195 Table 11-3.10: Storm Drain Inlet Protection Type of Inlet Pro- Emergency Applicable for tection Overflow Paved/ Earthen Sur- Conditions of Use faces Drop Inlet Protection Yes, temporary Applicable for heavy flows. Easy Excavated drop flooding may Earthen to maintain. Large area requirement: inlet protection occur 30'x30'/acre Block and gravel Applicable for heavy concentrated flows. drop inlet pro- Yes Paved or Earthen Will not pond. tection Gravel and wire Applicable for heavy concentrated flows. drop inlet pro- No Paved or Earthen Will pond. Can withstand traffic. tection Catch basin filters Yes Paved or Earthen Frequent maintenance required. Curb Inlet Protection Curb inlet pro- Small capacity Used for sturdy, more compact install- tection with overflow Paved ation. wooden weir Block and gravel curb inlet pro- Yes Paved Sturdy, but limited filtration. tection Culvert Inlet Protection Culvert inlet sed- N/A N/A 18 month expected life. iment trap Design and Installation Specifications Excavated Drop Inlet Protection Excavated drop inlet protection consists of an excavated impoundment around the storm drain inlet. Sediment settles out of the stormwater prior to entering the storm drain. Design and installation spe- cifications for excavated drop inlet protection include: . Provide a depth of 1-2 ft as measured from the crest of the inlet structure. . Slope sides of excavation should be no steeper than 2H:1 V. . Minimum volume of excavation is 35 cubic yards. Shape the excavation to fit the site, with the longest dimension oriented toward the longest inflow area. . Install provisions for draining to prevent standing water. . Clear the area of all debris. 2019 Stormwater Management Manual for Western Washington Volume 11- Chapter 3 - Page 357 121/195 • Grade the approach to the inlet uniformly. • Drill weep holes into the side of the inlet. • Protect weep holes with screen wire and washed aggregate. • Seal weep holes when removing structure and stabilizing area. • Build a temporary dike, if necessary, to the down slope side of the structure to prevent bypass flow. Block and Gravel Filter A block and gravel filter is a barrier formed around the inlet with standard concrete blocks and gravel. See Figure II-3.17: Block and Gravel Filter. Design and installation specifications for block gravel fil- ters include: • Provide a height of 1 to 2 feet above the inlet. • Recess the first row of blocks 2-inches into the ground for stability. • Support subsequent courses by placing a pressure treated wood 2x4 through the block open- ing. • Do not use mortar. • Lay some blocks in the bottom row on their side to allow for dewatering the pool. • Place hardware cloth or comparable wire mesh with'/2-inch openings over all block openings. • Place gravel to just below the top of blocks on slopes of 2H:1 V or flatter. . An alternative design is a gravel berm surrounding the inlet, as follows: • Provide a slope of 3H:1 V on the upstream side of the berm. • Provide a slope of 2H:1 V on the downstream side of the berm. • Provide a 1-foot wide level stone area between the gravel berm and the inlet. Use stones 3 inches in diameter or larger on the upstream slope of the berm. Use gravel'/2- to 3/4-inch at a minimum thickness of 1-foot on the downstream slope of the berm. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 358 122/195 Figure II-3.17: Block and Gravel Filter Drain grate a �595 CPC In, Plan View crete block Gravel backfill Concrete block Wire screen or filter fabric Gravel backfill Overflow waterer —I�� (�Ponding height on o9'� II Water I II I I I I n ^� fino Drop inlet Section A -A Notes: 1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less than 5%) 2. Excavate a basin of sufficient size adjacent to the drop inlet. 3. The top of the structure (ponding height) must be well below the ground elevation downslope to prevent runoff from bypassing the inlet. A temporary dike may be necessary on the downslope side of the structure. NOT TO SCALE Block and Gravel Filter Revised June 2016 DEPARTMENT OF ECOLOGYPlease see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 359 123/195 Gravel and Wire Mesh Filter Gravel and wire mesh filters are gravel barriers placed over the top of the inlet. This method does not provide an overflow. Design and installation specifications for gravel and wire mesh filters include: • Use a hardware cloth or comparable wire mesh with'/2-inch openings. Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot bey- ond each side of the inlet structure. Overlap the strips if more than one strip of mesh is necessary. • Place coarse aggregate over the wire mesh. Provide at least a 12-inch depth of aggregate over the entire inlet opening and extend at least 18-inches on all sides. Catch Basin Filters Catch basin filters are designed by manufacturers for construction sites. The limited sediment stor- age capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. To reduce maintenance requirements, combine a catch basin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights -of -way. Design and install- ation specifications for catch basin filters include: • Provides 5 cubic feet of storage. • Requires dewatering provisions. • Provides a high -flow bypass that will not clog under normal use at a construction site. . Insert the catch basin filter in the catch basin just below the grating. Curb Inlet Protection with Wooden Weir Curb inlet protection with wooden weir is an option that consists of a barrier formed around a curb inlet with a wooden frame and gravel. Design and installation specifications for curb inlet protection with wooden weirs include: • Use wire mesh with'/2-inch openings. • Use extra strength filter cloth. • Construct a frame. . Attach the wire and filter fabric to the frame. • Pile coarse washed aggregate against the wire and fabric. • Place weight on the frame anchors. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 360 124/195 Block and Gravel Curb Inlet Protection Block and gravel curb inlet protection is a barrier formed around a curb inlet with concrete blocks and gravel. See Figure 11-3.18: Block and Gravel Curb Inlet Protection. Design and installation spe- cifications for block and gravel curb inlet protection include: • Use wire mesh with'/2-inch openings. • Place two concrete blocks on their sides abutting the curb at either side of the inlet opening. These are spacer blocks. • Place a 2A stud through the outer holes of each spacer block to align the front blocks. • Place blocks on their sides across the front of the inlet and abutting the spacer blocks. • Place wire mesh over the outside vertical face. • Pile coarse aggregate against the wire to the top of the barrier. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 361 125/195 Figure II-3.18: Block and Gravel Curb Inlet Protection n Back of sidewalk Back of curb Wire scre filter %a << . Drain gravel Plan View 3/4 inch (20 mm) Drain gravel Wire screen or filter fabric 2x4 Wood stud (100x50 Timber stud) Ponding height Overflow ANNow Catch basin Concrete block ud block Section A -A Notes: 1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shall allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. NOT TO SCALE Block and Gravel Curb Inlet Protection Revised June 2016 DEPARTMENT OF ECOLOGYPlease see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 362 126/195 Curb and Gutter Sediment Barrier Curb and gutter sediment barrier is a sandbag or rock berm (riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure II-3.19: Curb and Gutter Barrier. Design and installation specifications for curb and gutter sediment barrier include: Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. . Construct a horseshoe shaped sedimentation trap on the upstream side of the berm. Size the trap to sediment trap standards for protecting a culvert inlet. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 363 127/195 Figure II-3.19: Curb and Gutter Barrier Back of sidewalk Burlap sacks to overlap onto curb Back of curb Runoff � " I��1-- Curb inlet Runoff Spillway Catch basin Plan View Gravel filled sandbags stacked tightly Notes: 1. Place curb type sediment barriers on gently sloping street segments, where water can pond and allow sediment to separate from runoff. 2. Sandbags of either burlap or woven 'geotextile' fabric, are filled with gravel, layered and packed tightly. 3. Leave a one sandbag gap in the top row to provide a spillway for overflow. 4. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. NOT TO SCALE DEPARTMENT OF ECOLOGY State of Washington Curb and Gutter Barrier Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 364 128/195 Maintenance Standards Inspect all forms of inlet protection frequently, especially after storm events. Clean and replace clogged catch basin filters. For rock and gravel filters, pull away the rocks from the inlet and clean or replace. An alternative approach would be to use the clogged rock as fill and put fresh rock around the inlet. Do not wash sediment into storm drains while cleaning. Spread all excavated material evenly over the surrounding land area or stockpile and stabilize as appropriate. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology's website at: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies 2019 Stormwater Management Manual for Western Washington Volume // - Chapter 3 - Page 365 129/195 BMP C233: Silt Fence Purpose Silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use Silt fence may be used downslope of all disturbed areas. Silt fence shall prevent sediment carried by runoff from going beneath, through, or over the top of the silt fence, but shall allow the water to pass through the fence. Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Convey any concentrated flows through the drainage system to a sediment trapping BMP. Do not construct silt fences in streams or use in V-shaped ditches. Silt fences do not provide an adequate method of silt control for anything deeper than sheet or overland flow. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 370 130/195 Figure 11-3.22: Silt Fence Joints in geotextile fabric shall be spliced at posts. Use staples, wire rings or equivalent to attach fabric to posts 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used —:\—\i\—�i1�\LLB%`\\/.��i�\/\\!`\ Minimum I I 6' max I I 4"x4" trench u Post spacing may be increased to 8' if wire backing is used 2"x2" wood posts, steel fence posts, or equivalent DEPARTMENT OF ECOLOGY State of Washington 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used Geotextile fabric 2' min Backfill trench with native soil or 4" - /\� 1.5" washed gravel �j12' min Minimum 47x4" trench 27x2" wood posts, steel fence posts, or equivalent Silt Fence NOT TO SCALE Revised July 2017 Please see http://www.ecy.wa.gov/cop3aVht.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 371 131/195 Design and Installation Specifications . Use in combination with other construction stormwater BMPs. Maximum slope steepness (perpendicular to the silt fence line) 1 H:1 V. Maximum sheet or overland flow path length to the silt fence of 100 feet. Do not allow flows greater than 0.5 cfs. Use geotextile fabric that meets the following standards. All geotextile properties listed below are minimum average roll values (i.e., the test result for any sampled roll in a lot shall meet or exceed the values shown in Table 11-3.11: Geotextile Fabric Standards for Silt Fence): Table II-3.11: Geotextile Fabric Standards for Silt Fence Geotextile Property Minimum Average Roll Value 0.60 mm maximum for slit film woven (#30 sieve). Polymeric Mesh AOS 0.30 mm maximum for all other geotextile types (#50 sieve). (ASTM D4751) 0.15 mm minimum for all fabric types (#100 sieve). Water Permittivity 0.02 sec-1 minimum (ASTM D4491) Grab Tensile Strength 180 lbs. Minimum for extra strength fabric. (ASTM D4632) 100 Ibs minimum for standard strength fabric. Grab Tensile Strength 30% maximum (ASTM D4632) Ultraviolet Resistance 70% minimum (ASTM D4355) Support standard strength geotextiles with wire mesh, chicken wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the geotextile. Silt fence materials are available that have synthetic mesh backing attached. . Silt fence material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable construction life at a temperature range of 0°F to 120°F. One -hundred percent biodegradable silt fence is available that is strong, long lasting, and can be left in place after the project is completed, if permitted by the local jurisdiction. Refer to Figure 11-3.22: Silt Fence for standard silt fence details. Include the following Stand- ard Notes for silt fence on construction plans and specifications: The Contractor shall install and maintain temporary silt fences at the locations shown in the Plans. 2. Construct silt fences in areas of clearing, grading, or drainage prior to starting those activities. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 372 132/195 3. The silt fence shall have a 2-feet min. and a 2'/2-feet max. height above the original ground surface. 4. The geotextile fabric shall be sewn together at the point of manufacture to form fabric lengths as required. Locate all sewn seams at support posts. Alternatively, two sections of silt fence can be overlapped, provided that the overlap is long enough and that the adjacent silt fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. 5. Attach the geotextile fabric on the up -slope side of the posts and secure with staples, wire, or in accordance with the manufacturer's recommendations. Attach the geotextile fabric to the posts in a manner that reduces the potential for tearing. 6. Support the geotextile fabric with wire or plastic mesh, dependent on the properties of the geotextile selected for use. If wire or plastic mesh is used, fasten the mesh securely to the up -slope side of the posts with the geotextile fabric up -slope of the mesh. 7. Mesh support, if used, shall consist of steel wire with a maximum mesh spacing of 2- inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to the same level of ultraviolet radiation as the geotextile fabric it supports. 8. Bury the bottom of the geotextile fabric 4-inches min. below the ground surface. Backfill and tamp soil in place over the buried portion of the geotextile fabric, so that no flow can pass beneath the silt fence and scouring cannot occur. When wire or polymeric back-up support mesh is used, the wire or polymeric mesh shall extend into the ground 3-inches min. 9. Drive or place the silt fence posts into the ground 18-inches min. A 12—inch min. depth is allowed if topsoil or other soft subgrade soil is not present and 18-inches cannot be reached. Increase fence post min. depths by 6 inches if the fence is located on slopes of 3H :1 V or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to pre- vent overturning of the fence due to sediment loading. 10. Use wood, steel or equivalent posts. The spacing of the support posts shall be a max- imum of 6-feet. Posts shall consist of either: • Wood with minimum dimensions of 2 inches by 2 inches by 3 feet. Wood shall be free of defects such as knots, splits, or gouges. . No. 6 steel rebar or larger. . ASTM A 120 steel pipe with a minimum diameter of 1-inch. • U, T, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. • Other steel posts having equivalent strength and bending resistance to the post sizes listed above. 11. Locate silt fences on contour as much as possible, except at the ends of the fence, 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 373 133/195 where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. 12. If the fence must cross contours, with the exception of the ends of the fence, place check dams perpendicular to the back of the fence to minimize concentrated flow and erosion. The slope of the fence line where contours must be crossed shall not be steeper than 3H:1 V. . Check dams shall be approximately 1-foot deep at the back of the fence. Check dams shall be continued perpendicular to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. . Check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. Check dams shall be located every 10 feet along the fence where the fence must cross contours. Refer to Figure II-3.23: Silt Fence Installation by Slicing Method for slicing method details. The following are specifications for silt fence installation using the slicing method: 1. The base of both end posts must be at least 2- to 4-inches above the top of the geo- textile fabric on the middle posts for ditch checks to drain properly. Use a hand level or string level, if necessary, to mark base points before installation. 2. Install posts 3- to 4-feet apart in critical retention areas and 6- to 7-feet apart in standard applications. 3. Install posts 24-inches deep on the downstream side of the silt fence, and as close as possible to the geotextile fabric, enabling posts to support the geotextile fabric from upstream water pressure. 4. Install posts with the nipples facing away from the geotextile fabric. 5. Attach the geotextile fabric to each post with three ties, all spaced within the top 8- inches of the fabric. Attach each tie diagonally 45 degrees through the fabric, with each puncture at least 1-inch vertically apart. Each tie should be positioned to hang on a post nipple when tightening to prevent sagging. 6. Wrap approximately 6-inches of the geotextile fabric around the end posts and secure with 3 ties. 7. No more than 24-inches of a 36-inch geotextile fabric is allowed above ground level. 8. Compact the soil immediately next to the geotextile fabric with the front wheel of the tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the upstream side first and then each side twice for a total of four trips. Check and correct the silt fence installation for any deviation before compaction. Use a flat -bladed shovel to tuck the fabric deeper into the ground if necessary. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 374 134/195 Figure 11-3.23: Silt Fence Installation by Slicing Method Ponding height max. 24" Attach fabric to upstream side of post FLOW - Drive over each side of silt fence 2 to 4 times with device exerting 60 p.s.i. or greater POST SPACING: 7' max. on open runs 4' max. on pooling areas POST DEPTH: As much below ground as fabric above ground 100% compaction 11 1 100% com N No more than 24" of a 36" fabric is allowed above ground Operation Horizontal chisel point (76 mm width) Top of Fabric ` Belt I# topy 8" f Diagonal attachment doubles strength Attachment Details: • Gather fabric at posts, if needed. • Utilize three ties per post, all within top 8" of fabric. • Position each tie diagonally, puncturing holes vertically a minimum of 1" apart. • Hang each tie on a post nipple and tighten securely. Use cable ties (50 Ibs) or soft wire. Roll of silt fence Slicing blade (18 mm width) Vibratory plow is not acceptable because of horizontal compaction DEPARTMENT OF ECOLOGY State of Washington Fabric above ground 200 - 300mm F Post installed after compaction Silt Fence Completed Installation NOT TO SCALE Silt Fence Installation by Slicing Method Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 375 135/195 Maintenance Standards • Repair any damage immediately. . Intercept and convey all evident concentrated flows uphill of the silt fence to a sediment trap- ping BMP. . Check the uphill side of the silt fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence and remove the trapped sediment. • Remove sediment deposits when the deposit reaches approximately one-third the height of the silt fence, or install a second silt fence. • Replace geotextile fabric that has deteriorated due to ultraviolet breakdown. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 376 136/195 BMP C234: Vegetated Strip Purpose Vegetated strips reduce the transport of coarse sediment from a construction site by providing a physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use . Vegetated strips maybe used downslope of all disturbed areas. Vegetated strips are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to BMP C241: Sediment Pond (Temporary) or other sediment trapping BMP. The only circumstance in which overland flow can be treated solely by a vegetated strip, rather than by a sediment trapping BMP, is when the following criteria are met (see Table 1I- 3.12: Contributing Drainage Area for Vegetated Strips): Table II-3.12: Contributing Drainage Area for Vegetated Strips Average Contributing Area Slope Average Contributing Area Per- cent Slope Max Contributing area Flowpath Length 1.5H : 1 V or flatter 67% or flatter 100 feet 2H : 1 V or flatter 50% or flatter 115 feet 4H : W or flatter 25% or flatter 150 feet 6H : 1 V or flatter 16.7% or flatter 200 feet 10H : 1 V or flatter 10% or flatter 250 feet 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 376 137/195 Design and Installation Specifications The vegetated strip shall consist of a continuous strip of dense vegetation with topsoil for a min- imum of a 25-foot length along the flowpath. Grass -covered, landscaped areas are generally not adequate because the volume of sediment overwhelms the grass. Ideally, vegetated strips shall consist of undisturbed native growth with a well -developed soil that allows for infiltration of runoff. . The slope within the vegetated strip shall not exceed 4H:1 V. . The uphill boundary of the vegetated strip shall be delineated with clearing limits. Maintenance Standards . Any areas damaged by erosion or construction activity shall be seeded immediately and pro- tected by mulch. If more than 5 feet of the original vegetated strip width has had vegetation removed or is being eroded, sod must be installed. If there are indications that concentrated flows are traveling across the vegetated strip, storm - water runoff controls must be installed to reduce the flows entering the vegetated strip, or addi- tional perimeter protection must be installed. 2019 Stormwater Management Manual for Western Washington Volume ll - Chapter 3 - Page 377 138/195 BMP C235: Wattles Purpose Wattles are temporary erosion and sediment control barriers consisting of straw, compost, or other material that is wrapped in netting made of natural plant fiber or similar encasing material. They reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sed- iment. Conditions of Use Wattles shall consist of cylinders of plant material such as weed -free straw, coir, wood chips, excelsior, or wood fiber or shavings encased within netting made of natural plant fibers unaltered by synthetic materials. . Use wattles: In disturbed areas that require immediate erosion protection. On exposed soils during the period of short construction delays, or over winter months. o On slopes requiring stabilization until permanent vegetation can be established. The material used dictates the effectiveness period of the wattle. Generally, wattles are effect- ive for one to two seasons. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 377 139/195 Prevent rilling beneath wattles by entrenching and overlapping wattles to prevent water from passing between them. Design Criteria . See Figure 11-3.24: Wattles for typical construction details. • Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length. . Install wattles perpendicular to the flow direction and parallel to the slope contour. • Place wattles in shallow trenches, staked along the contour of disturbed or newly constructed slopes. Dig narrow trenches across the slope (on contour) to a depth of 3- to 5-inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas with high rainfall, the trenches should be dug to a depth of 5- to 7- inches, or 1 /2 to 2/3 of the thickness of the wattle. . Start building trenches and installing wattles from the base of the slope and work up. Spread excavated material evenly along the uphill slope and compact it using hand tamping or other methods. . Construct trenches at intervals of 10- to 25-feet depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches. . Install the wattles snugly into the trenches and overlap the ends of adjacent wattles 12 inches behind one another. . Install stakes at each end of the wattle, and at 4-foot centers along entire length of wattle. . If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. • Wooden stakes should be approximately 0.75 x 0.75 x 24 inches min. Willow cuttings or 3/8- inch rebar can also be used for stakes. • Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake pro- truding above the wattle. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 378 140/195 Figure II-3.24: Wattles Straw rolls must be placed along slope contours 10' - 25' (3-8m) Spacing depends on soil type and slope steepness Live Stake 7— 3' - 4' � f (1.2m) /// Sediment, organic matter, and native seeds are captured behind the rolls. 3" - 5" (75-125mm) V x 1" Stake l/ (25 x 25mm) Overlap adjacent rolls 12" behind one another 8" - 10" Dia. (200-250mm) wt NOTE: r 1. Straw roll installation requires the placement and secure staking of the roll in a trench, 3" - 5" (75-125mm) deep, dug on contour. Runoff must not be allowed to run under or around roll. NOT TO SCALE Wattles Revised December 2016 DEPARTMENT OF ECOLOGYplease see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 379 141/195 Maintenance Standards Wattles may require maintenance to ensure they are in contact with soil and thoroughly entrenched, especially after significant rainfall on steep sandy soils. . Inspect the slope after significant storms and repair any areas where wattles are not tightly abutted or water has scoured beneath the wattles. Approved as Functionally Equivalent Ecology has approved products as able to meet the requirements of this BMP. The products did not pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to accept these products, or may require additional testing prior to consideration for local use. Products that Ecology has approved as functionally equivalent are available for review on Ecology's website at: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-per- mittee-guidance-resources/Emerging-stormwater-treatment-technologies 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 380 142/195 BMP C236: Vegetative Filtration Purpose Vegetative filtration as a BMP is used in conjunction with detention storage in the form of portable tanks or BMP C241: Sediment Pond (Temporary), BMP C206: Level Spreader, and a pumping sys- tem with surface intake. Vegetative filtration improves turbidity levels of stormwater discharges by fil- tering runoff through existing vegetation where undisturbed forest floor duff layer or established lawn with thatch layer are present. Vegetative filtration can also be used to infiltrate dewatering waste from foundations, vaults, and trenches as long as runoff does not occur. Conditions of Use • For every five acres of disturbed soil use one acre of grass field, farm pasture, or wooded area. Reduce or increase this area depending on project size, ground water table height, and other site conditions. • Wetlands shall not be used for vegetative filtration. • Do not use this BMP in areas with a high ground water table, or in areas that will have a high seasonal ground water table during the use of this BMP. . This BMP may be less effective on soils that prevent the infiltration of the water, such as hard till. • Using other effective source control measures throughout a construction site will prevent the generation of additional highly turbid water and may reduce the time period or area need for this BMP. . Stop distributing water into the vegetated filtration area if standing water or erosion results. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 380 143/195 . On large projects that phase the clearing of the site, areas retained with native vegetation may be used as a temporary vegetative filtration area. Design Criteria Find land adjacent to the project site that has a vegetated field, preferably a farm field, or wooded area. . If the site does not contain enough vegetated field area consider obtaining permission from adjacent landowners (especially for farm fields). . Install a pump and downstream distribution manifold depending on the project size. Generally, the main distribution line should reach 100 to 200-feet long (large projects, or projects on tight soil, will require systems that reach several thousand feet long with numerous branch lines off of the main distribution line). . The manifold should have several valves, allowing for control over the distribution area in the field. . Install several branches of 4-inch diameter schedule 20 polyvinyl chloride (PVC), swaged -fit common septic tight -lined sewer line, or 6-inch diameter fire hose, which can convey the tur- bid water out to various sections of the field. See Figure II-3.25: Manifold and Branches in a Wooded, Vegetated Spray Field. Determine the branch length based on the field area geography and number of branches. Typ- ically, branches stretch from 200-feet to several thousand feet. Lay the branches on contour with the slope. . On uneven ground, sprinklers perform well. Space sprinkler heads so that spray patterns do not overlap. . On relatively even surfaces, a level spreader using 4-inch perforated pipe maybe used as an alternative option to the sprinkler head setup. Install drain pipe at the highest point on the field and at various lower elevations to ensure full coverage of the filtration area. Place the pipe with the holes up to allow for gentle weeping evenly out all holes. Leveling the pipe by staking and using sandbags may be required. To prevent over saturating of the vegetative filtration area, rotate the use of branches or spray heads. Repeat as needed based on monitoring the spray field. Table II-3.13: Flowpath Guidelines for Vegetative Filtration Average Slope Average Area % Slope Estimated Flowpath Length (ft) 1.5H:1V 67% 250 2H:1V 50% 200 4H:1V 25% 150 6H:1V 16.7% 115 10H:1V 10% 100 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 381 144/195 Figure II-3.25: Manifold and Branches in a Wooded, Vegetated Spray Field rb f� DEPARTMENT OF ECOLOGY State of Washington NOT TO SCALE Manifold and Branches in a Wooded, Vegetated Spray Field Revised June 2016 Please see http:llwww.ecy.wa.govlcopynght.htm/ for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume /I - Chapter 3 - Page 382 145/195 Maintenance Standards • Monitor the spray field on a daily basis to ensure that over saturation of any portion of the field doesn't occur at any time. The presence of standing puddles of water or creation of con- centrated flows visually signify that over saturation of the field has occurred. • Monitor the vegetated spray field all the way down to the nearest surface water, or farthest spray area, to ensure that the water has not caused overland or concentrated flows, and has not created erosion around the spray nozzle(s). • Do not exceed water quality standards for turbidity. • Ecology recommends that a separate inspection log be developed, maintained and kept with the existing site logbook to aid the operator conducting inspections. This separate "Field Filtra- tion Logbook" can also aid in demonstrating compliance with permit conditions. . Inspect the spray nozzles daily, at a minimum, for leaks and plugging from sediment particles. . If erosion, concentrated flows, or over saturation of the field occurs, rotate the use of branches or spray heads or move the branches to a new field location. . Check all branches and the manifold for unintended leaks. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 383 146/195 BMP C240: Sediment Trap Purpose A sediment trap is a small temporary ponding area with a gravel outlet used to collect and store sed- iment from sites during construction. Sediment traps, along with other perimeter controls, shall be installed before any land disturbance takes place in the drainage area. Conditions of Use Sediment traps are intended for use on sites where the tributary drainage area is less than 3 acres, with no unusual drainage features, and a projected build -out time of six months or less. The sediment trap is a temporary measure (with a design life of approximately 6 months) and shall be maintained until the tributary area is permanently protected against erosion by veget- ation and/or structures. Sediment traps are only effective in removing sediment down to about the medium silt size fraction. Runoff with sediment of finer grades (fine silt and clay) will pass through untreated, emphasizing the need to control erosion to the maximum extent first. Projects that are constructing permanent Flow Control BMPs, or Runoff Treatment BMPs that use ponding for treatment, may use the rough -graded or final -graded permanent BMP footprint for the temporary sediment trap. When permanent BMP footprints are used as tem- porary sediment traps, the surface area requirement of the sediment trap must be met. If the surface area requirement of the sediment trap is larger than the surface area of the per- manent BMP, then the sediment trap shall be enlarged beyond the permanent BMP footprint to comply with the surface area requirement. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 383 147/195 . A floating pond skimmer maybe used for the sediment trap outlet if approved by the Local Per- mitting Authority. Sediment traps may not be feasible on utility projects due to the limited work space or the short-term nature of the work. Portable tanks may be used in place of sediment traps for utility projects. Design and Installation Specifications • See Figure II-3.26: Cross Section of Sediment Trap and Figure II-3.27: Sediment Trap Outlet for details. . To determine the sediment trap geometry, first calculate the design surface area (SA) of the trap, measured at the invert of the weir. Use the following equation: SA = FS(Q2/Vs) where Q2 = o Option 1 - Single Event Hydrograph Method: Q2 = Peak volumetric flow rate calculated using a 10-minute time step from a Type 1A, 2-year, 24-hour frequency storm for the developed condition. The 10-year peak volu- metric flow rate shall be used if the project size, expected timing and duration of con- struction, or downstream conditions warrant a higher level of protection. o Option 2 - For construction sites that are less than 1 acre, the Rational Method may be used to determine Q2. Vs = The settling velocity of the soil particle of interest. The 0.02 mm (medium silt) particle with an assumed density of 2.65 g/cm3 has been selected as the particle of interest and has a set- tling velocity (Vs) of 0.00096 ft/sec. FS = A safety factor of 2 to account for non -ideal settling. Therefore, the equation for computing sediment trap surface area becomes: SA = 2 x Q2/0.00096 or 2080 square feet per cfs of inflow Sediment trap depth shall be 3.5 feet minimum from the bottom of the trap to the top of the overflow weir. . To aid in determining sediment depth, all sediment traps shall have a staff gauge with a prom- inent mark 1-foot above the bottom of the trap. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 384 148/195 Design the discharge from the sediment trap by using the guidance for discharge from tem- porary sediment ponds in BMP C241: Sediment Pond (Temporary). Maintenance Standards Sediment shall be removed from the trap when it reaches 1-foot in depth. . Any damage to the trap embankments or slopes shall be repaired. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 385 149/195 Figure II-3.26: Cross Section of Sediment Trap Surface area determined at top of weir 1' Min. 3.5' - 5' 1.5' Min. Flat Bottom Note: Trap may be formed by berm or by partial or complete excavation. DEPARTMENT OF ECOLOGY State of Washington %4" - 1.5" Washed gravel Geotextile 2" - 4" Rock Rip Rap Discharge to stabilized conveyance, outlet, or level spreader NOT TO SCALE Cross Section of Sediment Trap Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 386 150/195 Figure 11-3.27: Sediment Trap Outlet Native soil or compacted backfill DEPARTMENT OF ECOLOGY State of Washington 6' Min. 'I'Min. depth overflow spillway Geotextile Min. 1' depth 2" - 4" rock Min. 1' depth %4" - 1.5" washed gravel Sediment Trap Outlet NOT TO SCALE Revised June 2016 Please see http://www.ecy.wa.gov/cop3aVht.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume /I - Chapter 3 - Page 387 151/195 BMP C241: Sediment Pond (Temporary) Purpose Sediment ponds are temporary ponds used during construction to remove sediment from runoff ori- ginating from disturbed areas of the project site. Sediment ponds are typically designed to remove sediment no smaller than medium silt (0.02 mm). Consequently, they usually reduce turbidity only slightly. Conditions of Use . Use a sediment pond where the contributing drainage area to the pond is 3 acres or more. Ponds must be used in conjunction with other Construction Stormwater BMPs to reduce the amount of sediment flowing into the pond. • Do not install sediment ponds on sites where failure of the BMP would result in loss of life, damage to homes or buildings, or interruption of use or service of public roads or utilities. Also, sediment ponds are attractive to children and can be dangerous. Compliance with local ordin- ances regarding health and safety must be addressed. If fencing of the pond is required, show the type of fence and its location on the drawings in the Construction SWPPP. • Sediment ponds that can impound 10 acre-ft (435,600 cu-ft, or 3.26 million gallons) or more, or have an embankment of more than 6 feet, are subject to the Washington Dam Safety Regu- lations (Chapter 173-175 WAC). See BMP D.1: Detention Ponds for more information regard- ing dam safety considerations for detention ponds. • Projects that are constructing permanent Flow Control BMPs or Runoff Treatment BMPs that use ponding for treatment may use the rough -graded or final -graded permanent BMP foot- print for the temporary sediment pond. When permanent BMP footprints are used as tem- porary sediment ponds, the surface area requirement of the temporary sediment pond must be met. If the surface area requirement of the sediment pond is larger than the surface area of the permanent BMP, then the sediment pond shall be enlarged beyond the permanent BMP footprint to comply with the surface area requirement. The permanent control structure must be temporarily replaced with a control structure that only allows water to leave the temporary sediment pond from the surface or by pumping. Alternatively, the permanent control structure may used if it is temporarily modified by plug- ging any outlet holes below the riser. The permanent control structure must be installed as part of the permanent BMP after the site is fully stabilized. Design and Installation Specifications General See Figure II-3.28: Sediment Pond Plan View, Figure II-3.29: Sediment Pond Cross Section, and Figure 11-3.30: Sediment Pond Riser Detail for details. Use of permanent infiltration BMP footprints for temporary sediment ponds during 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 388 152/195 construction tends to clog the soils and reduce their capacity to infiltrate. If permanent infilt- ration BMP footprints are used, the sides and bottom of the temporary sediment pond must only be rough excavated to a minimum of 2 feet above final grade of the permanent infiltration BMP. Final grading of the permanent infiltration BMP shall occur only when all contributing drainage areas are fully stabilized. Any proposed permanent pretreatment BMP prior to the infiltration BMP should be fully constructed and used with the temporary sediment pond to help prevent clogging of the soils. See Element 13: Protect Low Impact Development BMPs for more information about protecting permanent infiltration BMPs. The pond shall be divided into two roughly equal volume cells by a permeable divider that will reduce turbulence while allowing movement of water between the cells. The divider shall be at least one-half the height of the riser, and at least one foot below the top of the riser. Wire - backed, 2- to 3-foot high, high strength geotextile fabric supported by treated 4"x4"s can be used as a divider. Alternatively, staked straw bales wrapped with geotextile fabric may be used. If the pond is more than 6 feet deep, a different divider design must be proposed. A riprap embankment is one acceptable method of separation for deeper ponds. Other designs that satisfy the intent of this provision are allowed as long as the divider is permeable, struc- turally sound, and designed to prevent erosion under and around the divider. The most common structural failure of sediment ponds is caused by piping. Piping refers to two phenomena: (1) water seeping through fine-grained soil, eroding the soil grain by grain and forming pipes or tunnels; and, (2) water under pressure flowing upward through a gran- ular soil with a head of sufficient magnitude to cause soil grains to lose contact and capability for support. The most critical construction practices to prevent piping are: • Tight connections between the riser and outlet pipe, and other pipe connections. • Adequate anchoring of the riser. • Proper soil compaction of the embankment and riser footing. • Proper construction of anti -seep devices. Sediment Pond Geometry To determine the sediment pond geometry, first calculate the design surface area (SA) of the pond, measured at the top of the riser pipe. Use the following equation: SA = 2 x Q2/0.00096 or 2080 square feet per cfs of inflow See BMP C240: Sediment Trap for more information on the above equation. The basic geometry of the pond can now be determined using the following design criteria: • Required surface area SA (from the equation above) at the top of the riser. • Minimum 3.5-foot depth from the top of the riser to the bottom of the pond. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 389 153/195 • Maximum 3H:1 V interior side slopes and maximum 2H:1 V exterior slopes. The interior slopes can be increased to a maximum of 2H:1 V if fencing is provided at or above the maximum water surface. . One foot of freeboard between the top of the riser and the crest of the emergency spillway. • Flat bottom. • Minimum 1-foot deep spillway. • Length -to -width ratio between 3:1 and 6:1. Sediment Pond Discharae The outlet for the pond consists of a combination of principal and emergency spillways. These out- lets must pass the peak runoff expected from the contributing drainage area for a 100-year storm. If, due to site conditions and basin geometry, a separate emergency spillway is not feasible, the prin- cipal spillway must pass the entire peak runoff expected from the 100-year storm. However, an attempt to provide a separate emergency spillway should always be made. Base the runoff cal- culations on the site conditions during construction. The flow through the dewatering orifice cannot be utilized when calculating the 100-year storm elevation because of its potential to become clogged; therefore, available spillway storage must begin at the principal spillway riser crest. The principal spillway designed by the procedures described below will result in some reduction in the peak rate of runoff. However, the design will not control the discharge flow rates to the extent required to comply with 1-3.4.7 MR7: Flow Control. The size of the contributing basin, the expected life of the construction project, the anticipated downstream effects, and the anticipated weather con- ditions during construction should be considered to determine the need for additional discharge con- trol. Principal Spillway: Determine the required diameter for the principal spillway (riser pipe). The dia- meter shall be the minimum necessary to pass the peak volumetric flow rate using a 15-minute time step from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Use Figure II- 3.31: Riser Inflow Curves to determine the riser diameter. To aid in determining sediment depth, one -foot intervals shall be prominently marked on the riser. Emergency Overflow Spillway: Size the emergency overflow spillway for the peak volumetric flow rate using a 10-minute time step from a Type 1A, 100-year, 24-hour frequency storm for the developed condition. See BMP D.1: Detention Ponds for additional guidance for Emergency Over- flow Spillway design Dewatering Orifice: Size of the dewatering orifice(s) (minimum 1-inch diameter) using a modified version of the discharge equation for a vertical orifice and a basic equation for the area of a circular orifice. Determine the required area of the orifice with the following equation: A — AS(2h)o.s ° OAx NOTgo•5 where Ao = orifice area (square feet) 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 390 154/195 AS = pond surface area (square feet) h = head of water above orifice (height of riser in feet) T = dewatering time (24 hours) g = acceleration of gravity (32.2 feet/second2) Convert the orifice area (in square feet) to the orifice diameter D (in inches): D=24x `°=13.54x Ao The vertical, perforated tubing connected to the dewatering orifice must be at least 2 inches larger in diameter than the orifice to improve flow characteristics. The size and number of perforations in the tubing should be large enough so that the tubing does not restrict flow. The orifice should control the flow rate. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 391 155/195 Figure II-3.28: Sediment Pond Plan View Key divider into slope to prevent flow around sides The pond length shall be 3 to 6 times the maximum pond width Inflow length Silt fence or equivalent divider Note: Pond may be formed by berm or by partial or complete excavation DEPARTMENT OF ECOLOGY State of Washington Sediment Pond Plan View Emergency overflow spillway Discharge to stabilized conveyance, outlet, or level spreader NOT TO SCALE Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 392 156/195 Figure 11-3.29: Sediment Pond Cross Section Riser pipe (principal spillway) open at top with trash rack Dewatering device (see riser detail) Wire -backed silt fence staked haybales wrapped with filter fabric, or equivalent divider DEPARTMENT OF ECOLOGY State of Washington 1.5' Dewatering orifice Crest of emergency spillway Concrete base (see riser detail) 6' Min. width. 'I'Min. Discharge to stabilized r- conveyance outlet or level spreader Embankment compacted 95% pervious materials such as gravel or clean sand shall not be used NOT TO SCALE Sediment Pond Cross Section Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 393 157/195 Figure II-3.30: Sediment Pond Riser Detail Polyethylene cap Perforated polyethylene drainage tubing, diameter min. 2" larger than dewatering orifice. Tubing shall comply with ASTM F667 and AASHTO M294. DEPARTMENT OF ECOLOGY State of Washington Provide adequate strapping Corrugated metal riser 3.5' min. Watertight coupling Tack weld 6" min. 18" min. Concrete base 2X riser dia. min. Dewatering orifice, schedule 40 steel stub min. diameter per calculations Alternatively, metal stakes and wire may be used to prevent flotation Sediment Pond Riser Detail NOT TO SCALE Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 394 158/195 too Co. Figure II-3.31: Riser Inflow Curves 0.1 HEAD IN FEET (measuIred from crest of riser) 10 0_,=9.739 DH"1 Q,,,.,=3.782 Da Hviz 0 in cfs. D and H in feet Slope change occurs at weir -orifice transition DEPARTMENT OF ECOLOGY State of Washington Riser Inflow Curves Revised June 2016 Please see http:/Mvww.ecy.wa.govlcopyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume ll - Chapter 3 - Page 395 159/195 Maintenance Standards Remove sediment from the pond when it reaches 1 foot in depth. Repair any damage to the pond embankments or slopes. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 396 160/195 BMP C250: Construction Stormwater Chemical Treatment Purpose This BMP applies when using chemicals to treat turbidity in stormwater by either batch or flow - through chemical treatment. Turbidity is difficult to control once fine particles are suspended in stormwater runoff from a con- struction site. BMP C241: Sediment Pond (Temporary) is effective at removing larger particulate matter by gravity settling, but is ineffective at removing smaller particulates such as clay and fine silt. Traditional Construction Stormwater BMPs may not be adequate to ensure compliance with the water quality standards for turbidity in the receiving water. Chemical treatment can reliably provide exceptional reductions of turbidity and associated pol- lutants. Chemical treatment may be required to meet turbidity stormwater discharge requirements, especially when construction proceeds through the wet season. Conditions of Use Formal written approval from Ecology is required for the use of chemical treatment, regardless of site size. See https://fortress.wa.gov/ecy/publications/SummaryPages/ecy070258.html for a copy of the Request for Chemical Treatment form. The Local Permitting Authority may also require review and approval. When authorized, the chemical treatment systems must be included in the Con- struction Stormwater Pollution Prevention Plan (SWPPP). Chemically treated stormwater discharged from construction sites must be nontoxic to aquatic organ- isms. The Chemical Technology Assessment Protocol - Ecology (CTAPE) must be used to evaluate chemicals proposed for stormwater treatment. Only chemicals approved by Ecology under the CTAPE may be used for stormwater treatment. The approved chemicals, their allowable application techniques (batch treatment or flow -through treatment), allowable application rates, and conditions of use can be found at the Department of Ecology Emerging Technologies website: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-permittee- guidance-resources/E merging-stormwater-treatment-technologies Background on Chemical Treatment Systems Coagulation and flocculation have been used for over a century to treat water. The use of coagu- lation and flocculation to treat stormwater is a very recent application. Experience with the treatment of water and wastewater has resulted in a basic understanding of the process, in particular factors 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 396 161/195 that affect performance. This experience can provide insights as to how to most effectively design and operate similar systems in the treatment of stormwater. Fine particles suspended in water give it a milky appearance, measured as turbidity. Their small size, often much less than 1 pm in diameter, give them a very large surface area relative to their volume. These fine particles typically carry a negative surface charge. Largely because of these two factors (small size and negative charge), these particles tend to stay in suspension for extended periods of time. Thus, removal is not practical by gravity settling. These are called stable suspensions. Chem- icals like polymers, as well as inorganic chemicals such as alum, speed the settling process. The added chemical destabilizes the suspension and causes the smaller particles to flocculate. The pro- cess consists of three primary steps: coagulation, flocculation, and settling or clarification. Ecology requires a fourth step, filtration, on all stormwater chemical treatment systems to reduce floc dis- charge and to provide monitoring prior to discharge. General Design and Installation Specifications • Chemicals approved for use in Washington State are listed on Ecology's TAPE website, http://www.ecy.wa.gov/programs/wq/stormwater/newtech/technologies.html, under the "Con- struction" tab. . Care must be taken in the design of the withdrawal system to minimize outflow velocities and to prevent floc discharge. Stormwater that has been chemically treated must be filtered through BMP C251: Construction Stormwater Filtration for filtration and monitoring prior to dis- charge. . System discharge rates must take into account downstream conveyance integrity. . The following equipment should be located on site in a lockable shed: • The chemical injector. • Secondary containment for acid, caustic, buffering compound, and treatment chemical. • Emergency shower and eyewash. • Monitoring equipment which consists of a pH meter and a turbidimeter. There are two types of systems for applying the chemical treatment process to stormwater: the batch chemical treatment system and the flow -through chemical treatment system. See below for further details for both types of systems. Batch Chemical Treatment Systems A batch chemical treatment system consists of four steps: coagulation, flocculation, clarification, and polishing and monitoring via filtration. Step 1: Coagulation Coagulation is the process by which negative charges on the fine particles are disrupted. By dis- rupting the negative charges, the fine particles are able to flocculate. Chemical addition is one method of destabilizing the suspension, and polymers are one class of chemicals that are generally effective. Chemicals that are used for this purpose are called coagulants. Coagulation is complete 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 397 162/195 when the suspension is destabilized by the neutralization of the negative charges. Coagulants per- form best when they are thoroughly and evenly dispersed under relatively intense mixing. This rapid mixing involves adding the coagulant in a manner that promotes rapid dispersion, followed by a short time period for destabilization of the particle suspension. The particles are still very small and are not readily separated by clarification until flocculation occurs. Step 2: Flocculation Flocculation is the process by which fine particles that have been destabilized bind together to form larger particles that settle rapidly. Flocculation begins naturally following coagulation, but is enhanced by gentle mixing of the destabilized suspension. Gentle mixing helps to bring particles in contact with one another such that they bind and continually grow to form "flocs." As the size of the flocs increase, they become heavier and settle. Step 3: Clarification The final step is the settling of the particles, or clarification. Particle density, size and shape are important during settling. Dense, compact flocs settle more readily than less dense, fluffy flocs. Because of this, flocculation to form dense, compact flocs is particularly important during chemical treatment. Water temperature is important during settling. Both the density and viscosity of water are affected by temperature; these in turn affect settling. Cold temperatures increase viscosity and dens- ity, thus slowing down the rate at which the particles settle. The conditions under which clarification is achieved can affect performance. Currents can affect set- tling. Currents can be produced by wind, by differences between the temperature of the incoming water and the water in the clarifier, and by flow conditions near the inlets and outlets. Quiescent water, such as that which occurs during batch clarification, provides a good environment for settling. One source of currents in batch chemical treatment systems is movement of the water leaving the clarifier unit. Because flocs are relatively small and light, the velocity of the water must be as low as possible. Settled flocs can be resuspended and removed by fairly modest currents. Step 4: Filtration After clarification, Ecology requires stormwater that has been chemically treated to be filtered and monitored prior to discharge. The sand filtration system continually monitors the stormwater effluent for turbidity and pH. If the discharge water is ever out of an acceptable range for turbidity or pH, the water is returned to the untreated stormwater pond where it will begin the treatment process again. Design and Installation of Batch Chemical Treatment Systems A batch chemical treatment system consists of a stormwater collection system (either a temporary diversion or the permanent site drainage system), an untreated stormwater storage pond, pumps, a chemical feed system, treatment cells, a filtering and monitoring system, and interconnecting piping. The batch treatment system uses a storage pond for untreated stormwater, followed by a minimum of two lined treatment cells. Multiple treatment cells allow for clarification of chemically treated water in one cell, while other cells are being filled or emptied. Treatment cells may be ponds or tanks. Ponds with constructed earthen embankments greater than six feet high or which impound more than 10 acre-feet are subject to the Washington Dam Safety Regulations (Chapter 173-175 WAC). 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 398 163/195 See BMP D.1: Detention Ponds for more information regarding dam safety considerations for ponds. Stormwater is collected at interception point(s) on the site and is diverted by gravity or by pumping to an untreated stormwater storage pond or other untreated stormwater holding area. The stormwater is stored until treatment occurs. It is important that the storage pond is large enough to provide adequate storage. The first step in the treatment sequence is to check the pH of the stormwater in the untreated storm - water storage pond. The pH is adjusted by the application of carbon dioxide or a base until the storm water in the untreated storage pond is within the desired pH range, 6.5 to 8.5. When used, carbon dioxide is added immediately downstream of the transfer pump. Typically sodium bicarbonate (bak- ing soda) is used as a base, although other bases may be used. When needed, base is added dir- ectly to the untreated stormwater storage pond. The stormwater is recirculated with the treatment pump to provide mixing in the storage pond. Initial pH adjustments should be based on daily bench tests. Further pH adjustments can be made at any point in the process. See BMP C252: Treating and Disposing of High pH Water for more information on pH adjustments as a part of chemical treat- ment. Once the stormwater is within the desired pH range (which is dependant on the coagulant being used), the stormwater is pumped from the untreated stormwater storage pond to a lined treatment cell as a coagulant is added. The coagulant is added upstream of the pump to facilitate rapid mixing The water is kept in the lined treatment cell for clarification. In a batch mode process, clarification typ ically takes from 30 minutes to several hours. Prior to discharge, samples are withdrawn for analysis of pH, coagulant concentration, and turbidity. If these levels are acceptable, the treated water is with drawn, filtered, and discharged. Several configurations have been developed to withdraw treated water from the treatment cell. The original configuration is a device that withdraws the treated water from just beneath the water sur- face using a float with adjustable struts that prevent the float from settling on the cell bottom. This reduces the possibility of picking up floc from the bottom of the cell. The struts are usually set at a min imum clearance of about 12 inches; that is, the float will come within 12 inches of the bottom of the cell. Other systems have used vertical guides or cables which constrain the float, allowing it to drift up and down with the water level. More recent designs have an H-shaped array of pipes, set on the hori- zontal.This scheme provides for withdrawal from four points rather than one. This configuration reduces the likelihood of sucking settled solids from the bottom. It also reduces the tendency for a vor tex to form. Inlet diffusers, a long floating or fixed pipe with many small holes in it, are also an option. Safety is a primary concern. Design should consider the hazards associated with operations, such as sampling. Facilities should be designed to reduce slip hazards and drowning. Tanks and ponds should have life rings, ladders, or steps extending from the bottom to the top. Sizing Batch Chemical Treatment Systems Chemical treatment systems must be designed to control the velocity and peak volumetric flow rate that is discharged from the system and consequently the project site. See Element 3: Control Flow Rates for further details on this requirement. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 399 164/195 The total volume of the untreated stormwater storage pond and treatment cells must be large enough to treat stormwater that is produced during multiple day storm events. It is recommended that at a minimum the untreated stormwater storage pond be sized to hold 1.5 times the volume of runoff generated from the site during the 10-year, 24-hour storm event. Bypass should be provided around the chemical treatment system to accommodate extreme storm events. Runoff volume shall be calculated using the methods presented in III-2.3 Single Event Hydrograph Method. Worst -case land cover conditions (i.e., producing the most runoff) should be used for analyses (in most cases, this would be the land cover conditionsjust prior to final landscaping). Primary settling should be encouraged in the untreated stormwater storage pond. A forebay with access for maintenance may be beneficial. There are two opposing considerations in sizing the treatment cells. A larger cell is able to treat a lar- ger volume of water each time a batch is processed. However, the larger the cell, the longer the time required to empty the cell. A larger cell may also be less effective at flocculation and therefore require a longer settling time. The simplest approach to sizing the treatment cell is to multiply the allowable discharge flow rate (as determined by the guidance in Element 3: Control Flow Rates) times the desired drawdown time. A 4-hour drawdown time allows one batch per cell per 8-hour work period, given 1 hour of flocculation followed by two hours of settling. See BMP C251: Construction Stormwater Filtration for details on sizing the filtration system at the end of the batch chemical treatment system. If the chemical treatment system design does not allow you to discharge at the rates as required by Element 3: Control Flow Rates, and if the site has a permanent Flow Control BMP that will serve the planned development, the discharge from the chemical treatment system may be directed to the per- manent Flow Control BMP to comply with Element 3: Control Flow Rates. In this case, all discharge (including water passing through the treatment system and stormwater bypassing the treatment sys- tem) will be directed into the permanent Flow Control BMP. If site constraints make locating the untreated stormwater storage pond difficult, the permanent Flow Control BMP may be divided to serve as the untreated stormwater storage pond and the post -treatment temporary flow control pond. A berm or barrier must be used in this case so the untreated water does not mix with the treated water. Both untreated stormwater storage requirements, and adequate post -treatment flow control must be achieved. The designer must document in the Construction SWPPP how the per- manent Flow Control BMP is able to attenuate the discharge from the site to meet the requirements of Element 3: Control Flow Rates. If the design of the permanent Flow Control BMP was modified for temporary construction flow control purposes, the construction of the permanent Flow Control BMP must be finalized, as designed for its permanent function, at project completion. Flow -Through Chemical Treatment Systems Background on Flow -Through Chemical Treatment Systems A flow -through chemical treatment system adds a sand filtration component to the batch chemical treatment system's treatment train following flocculation. The coagulant is added to the stormwater upstream of the sand filter so that the coagulation and flocculation step occur immediately prior to the filter. The advantage of a flow -through chemical treatment system is the time saved by immediately filtering the water, as opposed to waiting for the clarification process necessary in a batch chemical 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 400 165/195 treatment system. See BMP C251: Construction Stormwater Filtration for more information on fil- tration. Desian and Installation of Flow-Throuah Chemical Treatment Svstems At a minimum, a flow -through chemical treatment system consists of a stormwater collection system (either a temporary diversion or the permanent site drainage system), an untreated stormwater stor- age pond, and a chemically enhanced sand filtration system. As with a batch treatment system, stormwater is collected at interception point(s) on the site and is diverted by gravity or by pumping to an untreated stormwater storage pond or other untreated storm. water holding area. The stormwater is stored until treatment occurs. It is important that the holding pond be large enough to provide adequate storage. Stormwater is then pumped from the untreated stormwater storage pond to the chemically enhanced sand filtration system where a coagulant is added. Adjustments to pH may be necessary before coagulant addition. The sand filtration system continually monitors the stormwater effluent for turbidity and pH. If the discharge water is ever out of an acceptable range for turbidity or pH, the water is returned to the untreated stormwater pond where it will begin the treatment process again. Sizing Flow -Through Chemical Treatment Systems Refer to BMP C251: Construction Stormwater Filtration for sizing requirements of flow -through chemical treatment systems. Factors Affecting the Chemical Treatment Process Coagulants Cationic polymers can be used as coagulants to destabilize negatively charged turbidity particles present in natural waters, wastewater and stormwater. Polymers are large organic molecules that are made up of subunits linked together in a chain -like structure. Attached to these chain -like struc- tures are other groups that carry positive or negative charges, or have no charge. Polymers that carry groups with positive charges are called cationic, those with negative charges are called anionic, and those with no charge (neutral) are called nonionic. In practice, the only way to determ- ine whether a polymer is effective for a specific application is to perform preliminary or on -site test- ing. Aluminum sulfate (alum) can also be used as a coagulant, as this chemical becomes positively charged when dispersed in water. Polymers are available as powders, concentrated liquids, and emulsions (which appear as milky liquids). The latter are petroleum based, which are not allowed for construction stormwater treat- ment. Polymer effectiveness can degrade with time and also from other influences. Thus, man- ufacturers' recommendations for storage should be followed. Manufacturer's recommendations usually do not provide assurance of water quality protection or safety to aquatic organisms. Con- sideration of water quality protection is necessary in the selection and use of all polymers. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 401 166/195 Application Application of coagulants at the appropriate concentration or dosage rate for optimum turbidity removal is important for management of chemical cost, for effective performance, and to avoid aquatic toxicity. The optimum dose in a given application depends on several site -specific features. Turbidity of untreated water can be important with turbidities greater than 5,000 NTU. The surface charge of particles to be removed is also important. Environmental factors that can influence dosage rate are water temperature, pH, and the presence of constituents that consume or otherwise affect coagulant effectiveness. Laboratory experiments indicate that mixing previously settled sediment (floc sludge) with the untreated stormwater significantly improves clarification, therefore reducing the effective dosage rate. Preparation of working solutions and thorough dispersal of coagulants in water to be treated is also important to establish the appropriate dosage rate. For a given water sample, there is generally an optimum dosage rate that yields the lowest residual turbidity after settling. When dosage rates below this optimum value (underdosing) are applied, there is an insufficient quantity of coagulant to react with, and therefore destabilize, all of the turbidity present. The result is residual turbidity (after flocculation and settling) that is higher than with the optimum dose. Overdosing, application of dosage rates greater than the optimum value, can also negatively impact performance. Like underdosing, the result of overdosing is higher residual turbidity than that with the optimum dose. Mixing The G-value, or just "G", is often used as a measure of the mixing intensity applied during coagu- lation and flocculation. The symbol G stands for "velocity gradient", which is related in part to the degree of turbulence generated during mixing. High G-values mean high turbulence, and vice versa. High G-values provide the best conditions for coagulant addition. With high G's, turbulence is high and coagulants are rapidly dispersed to their appropriate concentrations for effective destabilization of particle suspensions. Low G-values provide the best conditions for flocculation. Here, the goal is to promote formation of dense, compact flocs that will settle readily. Low G's provide low turbulence to promote particle col- lisions so that flocs can form. Low G's generate sufficient turbulence such that collisions are effective in floc formation, but do not break up flocs that have already formed. pH Adjustment The pH must be in the proper range for the coagulants to be effective, which is typically 6.5 to 8.5. As polymers tend to lower the pH, it is important that the stormwater have sufficient buffering capacity. Buffering capacity is a function of alkalinity. Without sufficient alkalinity, the application of the polymer may lower the pH to below 6.5. A pH below 6.5 not only reduces the effectiveness of the polymer as a coagulant, but it may also create a toxic condition for aquatic organisms. Stormwater may not be discharged without readjustment of the pH to above 6.5. The target pH should be within 0.2 stand- ard units of the receiving water's pH. Experience gained at several projects in the City of Redmond has shown that the alkalinity needs to be at least 50 mg/L to prevent a drop in pH to below 6.5 when the polymer is added. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 402 167/195 Maintenance Standards Monitoring At a minimum, the following monitoring shall be conducted. Test results shall be recorded on a daily log kept on site. Additional testing may be required by the N PDES permit based on site conditions. Operational Monitoring • Total volume treated and discharged. • Flow must be continuously monitored and recorded at not greater than 15-minute inter- vals. • Type and amount of chemical used for pH adjustment. • Type and amount of coagulant used for treatment. • Settling time. Compliance Monitoring Influent and effluent pH, flocculent chemical concentration, and turbidity must be con- tinuously monitored and recorded at not greater than 15-minute intervals. o pH and turbidity of the receiving water. . Biomonitoring Treated stormwater must be non -toxic to aquatic organisms. Treated stormwater must be tested for aquatic toxicity or residual chemicals. Frequency of biomonitoring will be determined by Ecology. Residual chemical tests must be approved by Ecology prior to their use. If testing treated stormwater for aquatic toxicity, you must test for acute (lethal) toxicity. Bioassays shall be conducted by a laboratory accredited by Ecology, unless otherwise approved by Ecology. Acute toxicity tests shall be conducted per the CTAPE protocol and Appendix G of Whole Effluent Toxicity Testing Guidance and Test Review Criteria (Marshall, 2016). Discharge Compliance Prior to discharge, treated stormwater must be sampled and tested for compliance with pH, floc- culent chemical concentration, and turbidity limits. These limits may be established by the Con- struction Stormwater General Permit or a site -specific discharge permit. Sampling and testing for other pollutants may also be necessary at some sites. pH must be within the range of 6.5 to 8.5 stand- ard units and not cause a change in the pH of the receiving water by more than 0.2 standard units. Treated stormwater samples and measurements shall be taken from the discharge pipe or another location representative of the nature of the treated stormwater discharge. Samples used for determ- ining compliance with the water quality standards in the receiving water shall not be taken from the 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 403 168/195 treatment pond prior to decanting. Compliance with the water quality standards is determined in the receiving water. Operator Training Each project site using chemical treatment must have a trained operator who is certified for oper- ation of an Enhanced Chemical Treatment system. The operator must be trained and certified by an organization approved by Ecology. Organizations approved for operator training are found at the fol- lowing website: https://ecology.wa.gov/Regulations-Permits/Guidance-technical-assistance/Stormwater-permittee- quidance-resou rces/Contaminated-water-on-construction-sites Sediment Removal and Disposal Sediment shall be removed from the untreated stormwater storage pond and treatment cells as necessary. Typically, sediment removal is required at least once during a wet season and at the decommissioning of the chemical treatment system. Sediment remaining in the cells between batches may enhance the settling process and reduce the required chemical dosage. Sediment that is known to be non -toxic maybe incorporated into the site away from drain- ages. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 404 169/195 BMP C251: Construction Stormwater Filtration Purpose Filtration removes sediment from runoff originating from disturbed areas of the site. Conditions of Use Traditional Construction Stormwater BMPs used to control soil erosion and sediment loss from con- struction sites may not be adequate to ensure compliance with the water quality standard for tur- bidity in the receiving water. Filtration may be used in conjunction with gravity settling to remove sediment as small as fine silt (0.5 pm). The reduction in turbidity will be dependent on the particle size distribution of the sediment in the stormwater. In some circumstances, sedimentation and fil- tration may achieve compliance with the water quality standard for turbidity. The use of construction stormwater filtration does not require approval from Ecology as long as treat- ment chemicals are not used. Filtration in conjunction with BMP C250: Construction Stormwater Chemical Treatment requires testing under the Chemical Technology Assessment Protocol — Eco- logy (CTAPE) before it can be initiated. Approval from Ecology must be obtained at each site where chemical use is proposed prior to use. See https://- fortress.wa.gov/ecy/publications/SummaryPages/ecy07O258.html for a copy of the Request for Chemical Treatment form. 2019 Stormwater Management Manual for Western Washington Volume // - Chapter 3 - Page 404 170/195 Design and Installation Specifications Two types of filtration systems may be applied to construction stormwater treatment: rapid and slow. Rapid filtration systems are the typical system used for water and wastewater treatment. They can achieve relatively high hydraulic flow rates, on the order of 2 to 20 gpm/sf, because they have auto- matic backwash systems to remove accumulated solids. Slow filtration systems have very low hydraulic rates, on the order of 0.02 gpm/sf, because they do not have backwash systems. Slow filtration systems have generally been used as post construction BMPs to treat stormwater (see V-6 Filtration BMPs). Slow filtration is mechanically simple in com- parison to rapid filtration, but requires a much larger filter area. Filter Twes and Efficiencies Sand media filters are available with automatic backwashing features that can filter to 50 pm particle size. Screen or bag filters can filter down to 5 pm. Fiber wound filters can remove particles down to 0.5 pm. Filters should be sequenced from the largest to the smallest pore opening. Sediment removal efficiency will be related to particle size distribution in the stormwater. Treatment Process and Descri Stormwater is collected at interception point(s) on the site and diverted to an untreated stormwater sediment pond or tank for removal of large sediment, and storage of the stormwater before it is treated by the filtration system. In a rapid filtration system, the untreated stormwater is pumped from the pond or tank through the filtration media. Slow filtration systems are designed using gravity to convey water from the pond or tank to and through the filtration media. Sizing Filtration treatment systems must be designed to control the velocity and peak volumetric flow rate that is discharged from the system and consequently the project site. See Element 3: Control Flow Rates for further details on this requirement. The untreated stormwater storage pond or tank should be sized to hold 1.5 times the volume of run- off generated from the site during the 10-year, 24-hour storm event, minus the filtration treatment system flowrate for an 8-hour period. For a chitosan-enhanced sand filtration system, the filtration treatment system flowrate should be sized using a hydraulic loading rate between 6-8 gpm/ft2.Other hydraulic loading rates may be more appropriate for other systems. Bypass should be provided around the filtration treatment system to accommodate extreme storm events. Runoff volume shall be calculated using the methods presented in III-2.3 Single Event Hydrograph Method. Worst -case land cover conditions (i.e., producing the most runoff) should be used for analyses (in most cases, this would be the land cover conditionsjust prior to final landscaping). If the filtration treatment system design does not allow you to discharge at the rates as required by Element 3: Control Flow Rates, and if the site has a permanent Flow Control BMP that will serve the planned development, the discharge from the filtration treatment system may be directed to the per- manent Flow Control BMP to comply with Element 3: Control Flow Rates. In this case, all discharge (including water passing through the treatment system and stormwater bypassing the treatment 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 405 171/195 system) will be directed into the permanent Flow Control BMP. If site constraints make locating the untreated stormwater storage pond difficult, the permanent Flow Control BMP may be divided to serve as the untreated stormwater storage pond and the post -treatment temporary flow control pond. A berm or barrier must be used in this case so the untreated water does not mix with the treated water. Both untreated stormwater storage requirements, and adequate post -treatment flow control must be achieved. The designer must document in the Construction SWPPP how the per- manent Flow Control BMP is able to attenuate the discharge from the site to meet the requirements of Element 3: Control Flow Rates. If the design of the permanent Flow Control BMP was modified for temporary construction flow control purposes, the construction of the permanent Flow Control BMP must be finalized, as designed for its permanent function, at project completion. Maintenance Standards • Rapid sand filters typically have automatic backwash systems that are triggered by a pre-set pressure drop across the filter. If the backwash water volume is not large or substantially more turbid than the untreated stormwater stored in the holding pond or tank, backwash return to the untreated stormwater pond or tank may be appropriate. However, other means of treat- ment and disposal may be necessary. . Screen, bag, and fiber filters must be cleaned and/or replaced when they become clogged. . Sediment shall be removed from the storage and/or treatment ponds as necessary. Typically, sediment removal is required once or twice during a wet season and at the decommissioning of the ponds. • Disposal of filtration equipment must comply with applicable local, state, and federal reg- ulations. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 406 172/195 BMP C252: Treating and Disposing of High pH Water Purpose When pH levels in stormwater rise above 8.5, it is necessary to lower the pH levels to the acceptable range of 6.5 to 8.5 prior to discharge to surface or ground water. A pH level range of 6.5 to 8.5 is typ- ical for most natural watercourses, and this neutral pH range is required for the survival of aquatic organisms. Should the pH rise or drop out of this range, fish and other aquatic organisms may become stressed and may die. Conditions of Use . The water quality standard for pH in Washington State is in the range of 6.5 to 8.5. Storm - water with pH levels exceeding water quality standards may be either neutralized on site or disposed of to a sanitary sewer or concrete batch plant with pH neutralization capabilities. Neutralized stormwater may be discharged to surface waters under the Construction Storm - water General permit. Neutralized process water such as concrete truck wash -out, hydro -demolition, or saw -cutting slurry must be managed to prevent discharge to surface waters. Any stormwater 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 406 173/195 contaminated during concrete work is considered process wastewater and must not be dis- charged to waters of the State or stormwater collection systems. . The process used for neutralizing and/or disposing of high pH stormwater from the site must be documented in the Construction Stormwater Pollution Prevention Plan. Causes of High pH High pH at construction sites is most commonly caused by the contact of stormwater with poured or recycled concrete, cement, mortars, and other Portland cement or lime containing construction materials. (See BMP C151: Concrete Handling for more information on concrete handling pro- cedures). The principal caustic agent in cement is calcium hydroxide (free lime). Calcium hardness can contribute to high pH values and cause toxicity that is associated with high pH conditions. A high level of calcium hardness in waters of the state is not allowed. Ground water stand- ard for calcium and other dissolved solids in Washington State is less than 500 mg/l. Treating High pH Stormwater by Carbon Dioxide Sparging Advantages of Carbon Dioxide Sparging • Rapidly neutralizes high pH water. • Cost effective and safer to handle than acid compounds. • CO2 is self -buffering. It is difficult to overdose and create harmfully low pH levels. • Material is readily available. The Chemical Process of Carbon Dioxide Sparging When carbon dioxide (CO2) is added to water (H2O), carbonic acid (H2CO3) is formed which can further dissociate into a proton (H+) and a bicarbonate anion (HCO3-) as shown below: CO2 + H2O H H2CO3 H H+ + HCO3- The free proton is a weak acid that can lower the pH. Water temperature has an effect on the reac- tion as well. The colder the water temperature is, the slower the reaction occurs. The warmer the water temperature is, the quicker the reaction occurs. Most construction applications in Washington State have water temperatures in the 50°F or higher range so the reaction is almost simultaneous. The Treatment Process of Carbon Dioxide Sparqinq High pH water may be treated using continuous treatment, continuous discharge systems. These manufactured systems continuously monitor influent and effluent pH to ensure that pH values are within an acceptable range before being discharged. All systems must have fail safe automatic shut off switches in the event that pH is not within the acceptable discharge range. Only trained operators may operate manufactured systems. System manufacturers often provide trained operators or train- ing on their devices. The following procedure may be used when not using a continuous discharge system: 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 407 174/195 1. Prior to treatment, the appropriate jurisdiction should be notified in accordance with the reg- ulations set by the jurisdiction. 2. Every effort should be made to isolate the potential high pH water in order to treat it separately from other stormwater on -site. 3. Water should be stored in an acceptable storage facility, detention pond, or containment cell prior to pH treatment. 4. Transfer water to be treated for pH to the pH treatment structure. Ensure that the pH treat- ment structure size is sufficient to hold the amount of water that is to be treated. Do not fill the pH treatment structure completely, allow at least 2 feet of freeboard. 5. The operator samples the water within the pH treatment structure for pH and notes the clarity of the water. As a rule of thumb, less CO2 is necessary for clearer water. The results of the samples and water clarity observations should be recorded. 6. In the pH treatment structure, add CO2 until the pH falls into the range of 6.9-7.1. Adjusting pH to within 0.2 pH units of receiving water (background pH) is recommended. It is unlikely that pH can be adjusted to within 0.2 pH units using dry ice. Compressed carbon dioxide gas should be introduced to the water using a carbon dioxide diffuser located near the bottom of the pH treatment structure, this will allow carbon dioxide to bubble up through the water and diffuse more evenly. 7. Slowly discharge the water, making sure water does not get stirred up in the process. Release about 80% of the water from the pH treatment structure leaving any sludge behind. If turbidity remains above the maximum allowable, consider adding filtration to the treatment train. See BMP C251: Construction Stormwater Filtration. 8. Discharge treated water through a pond or drainage system. 9. Excess sludge needs to be disposed of properly as concrete waste. If several batches of water are undergoing pH treatment, sludge can be left in the treatment structure for the next batch treatment. Dispose of sludge when it fills 50% of the treatment structure volume. 10. Disposal must comply with applicable local, state, and federal regulations. Treating High pH Stormwater by Food Grade Vinegar Food grade vinegar that meets FDA standards may be used to neutralize high pH water. Food grade vinegar is only 4% to 18% acetic acid with the remainder being water. Food grade vinegar may be used if dosed just enough to lower pH sufficiently. Use a treatment process as described above for CO2 sparging, but add food grade vinegar instead of CO2. This treatment option for high pH stormwater does not apply to anything but food grade vinegar. Acetic acid does not equal vinegar. Any other product or waste containing acetic acid must go through the evaluation process in Appendix G of Whole Effluent Toxicity Testing Guidance and Test Review Criteria (Marshall, 2016). 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 408 175/195 Disposal of High pH Stormwater Sanitary Sewer Disposal Local sewer authority approval is required prior to disposal via the sanitary sewer. Concrete Batch Plant Disposal . Only permitted facilities may accept high pH water. • Contact the facility to ensure they can accept the high pH water. Maintenance Standards Safety and materials handling: . All equipment should be handled in accordance with OSHA rules and regulations. • Follow manufacturer guidelines for materials handling. Each operator should provide: . A diagram of the monitoring and treatment equipment. . A description of the pumping rates and capacity the treatment equipment is capable of treat- ing. Each operator should keep a written record of the following: • Client name and phone number. • Date of treatment. • Weather conditions. • Project name and location. . Volume of water treated. • pH of untreated water. . Amount of CO2 or food grade vinegar needed to adjust water to a pH range of 6.9-7.1. • pH of treated water. • Discharge point location and description. A copy of this record should be given to the client/contractor who should retain the record for three years. 2019 Stormwater Management Manual for Western Washington Volume 11 - Chapter 3 - Page 409 176/195 S411 BMPs for Landscaping and Lawn / Vegetation Management Description of Pollutant Sources: Landscaping can include grading, soil transfer, vegetation planting, and vegetation removal. Examples include weed control on golf course lawns, access roads, and utility corridors and during landscaping; and residential lawn/plant care. Proper man- agement of vegetation can minimize excess nutrients and pesticides. 2019 Stormwater Management Manual for Western Washington Volume IV - Chapter 4 - Page 523 177/195 Pollutant Control Approach: Maintain appropriate vegetation to control erosion and the dis- charge of stormwater pollutants. Prevent debris contamination of stormwater. Where practicable, grow plant species appropriate for the site, or adjust the soil properties of the site to grow desired plant species. Applicable BMPs: . Install engineered soil/landscape systems to improve the infiltration and regulation of storm - water in landscaped areas. • Select the right plants for the planting location based on proposed use, available main- tenance,soil conditions, sun exposure, water availability, height, sight factors, and space avail- able. • Ensure that plants selected for planting are not on the noxious weed list. For example, but- terfly bush often gets planted as an ornamental but is actually on the noxious weed list. The Washington State Noxious Weed List can be found at the following webpage: https://www.nwcb.wa.gov/printable-noxious-weed-list • Do not dispose of collected vegetation into waterways or storm sewer systems. • Do not blow vegetation or other debris into the drainage system. • Dispose of collected vegetation such as grass clippings, leaves, sticks by composting or recyc- ling. • Remove, bag, and dispose of class A & B noxious weeds in the garbage immediately. • Do not compost noxious weeds as it may lead to spreading through seed or fragment if the composting process is not hot enough. • Use manual and/or mechanical methods of vegetation removal (pincer -type weeding tools, flame weeders, or hot water weeders as appropriate) rather than applying herbicides, where practical. • Use at least an eight -inch "topsoil" layer with at least 8 percent organic matter to provide a suf- ficient vegetation -growing medium. Organic matter is the least water-soluble form of nutrients that can be added to the soil. Composted organic matter generally releases only between 2 and 10 percent of its total nitrogen annually, and this release corresponds closely to the plant growth cycle. Return natural plant debris and mulch to the soil, to continue recycling nutrients indef- initely. . Select the appropriate turfgrass mixture for the climate and soil type. Certain tall fescues and rye grasses resist insect attack because the symbiotic endo- phytic fungi found naturally in their tissues repel or kill common leaf and stem -eating lawn insects. 2019 Stormwater Management Manual for Western Washington Volume IV - Chapter 4 - Page 524 178/195 ■ The fungus causes no known adverse effects to the host plant or to humans. ■ Tall fescues and rye grasses do not repel root -feeding lawn pests such as Crane Fly larvae. ■ Tall fescues and rye grasses are toxic to ruminants such as cattle and sheep • Endophytic grasses are commercially available; use them in areas such as parks or golf courses where grazing does not occur. • Local agricultural or gardening resources such as Washington State University Exten- sion office can offer advice on which types of grass are best suited to the area and soil type. • Use the following seeding and planting BMPs, or equivalent BMPs, to obtain information on grass mixtures, temporary and permanent seeding procedures, maintenance of a recently planted area, and fertilizer application rates: BMP C120: Temporary and Permanent Seeding, BMP C121: Mulching, BMP C123: Plastic Covering, and BMP C124: Sodding. . Adjusting the soil properties of the subject site can assist in selection of desired plant species. Consult a soil restoration specialist for site -specific conditions. Recommended Additional BMPs: . Conduct mulch -mowing whenever practicable. • Use native plants in landscaping. Native plants do not require extensive fertilizer or pesticide applications. Native plants may also require less watering. • Use mulch or other erosion control measures on soils exposed for more than one week during the dry season (May 1 to September 30) or two days during the rainy season (October 1 to April 30). . Till a topsoil mix or composted organic material into the soil to create a well -mixed transition layer that encourages deeper root systems and drought -resistant plants. . Apply an annual topdressing application of 3/8" compost. Amending existing landscapes and turf systems by increasing the percent organic matter and depth of topsoil can: • Substantially improve the permeability of the soil. • Increase the disease and drought resistance of the vegetation. • Reduces the demand for fertilizers and pesticides. . Disinfect gardening tools after pruning diseased plants to prevent the spread of disease. . Prune trees and shrubs in a manner appropriate for each species. . If specific plants have a high mortality rate, assess the cause and replace with another more appropriate species. • When working around and below mature trees, follow the most current American National Standards Institute (ANSI) ANSI A300 standards (see 2019 Stormwater Management Manual for Western Washington Volume /V - Chapter 4 - Page 525 179/195 ://www.tcia.orci/TCIA/BUSINESS/ANSI A300 Standards /TCIA/BUSINESS/A300 Standards/A300 Standards. aspx?h key= 202ff566-4364-4686-b7cl -2a365af59669) and International Society of Arboriculture BMPs to the extent practicable (e.g., take care to min- imize any damage to tree roots and avoid compaction of soil). Monitor tree support systems (stakes, guys, etc.). Repair and adjust as needed to provide support and prevent tree damage. Remove tree supports after one growing season or maximum of 1 year. Backfill stake holes after removal. • When continued, regular pruning (more than one time during the growing season) is required to maintain visual sight lines for safety or clearance along a walk or drive, consider relocating the plant to a more appropriate location. • Make reasonable attempts to remove and dispose of class C noxious weeds. • Re -seed bare turf areas until the vegetation fully covers the ground surface. • Watch for and respond to new occurrences of especially aggressive weeds such as H im- alayan blackberry, Japanese knotweed, morning glory, English ivy, and reed canary grass to avoid invasions. • Plant and protect trees per BMP T5.16: Tree Retention and Tree Planting. . Aerate lawns regularly in areas of heavy use where the soil tends to become compacted. Con- duct aeration while the grasses in the lawn are growing most vigorously. Remove layers of thatch greater than 3/4-inch deep. . Set the mowing height at the highest acceptable level and mow at times and intervals designed to minimize stress on the turf. Generally mowing only 1/3 of the grass blade height will prevent stressing the turf. O Mowing is a stress -creating activity for turfgrass. C3 Grass decreases its productivity when mowed too short and there is less growth of roots and rhizomes. The turf becomes less tolerant of environmental stresses, more dis- ease prone and more reliant on outside means such as pesticides, fertilizers, and irrig- ation to remain healthy. Additional BMP Information: • King County's Best Management Practices for Golf Course Development and Operation (King County, 1993) has additional BMPs for Turfgrass Maintenance and Operation. • King County, Seattle Public Utilities, and the Saving Water Partnership have created the fol- lowing natural lawn and garden care resources that include guidance on building healthy soil with compost and mulch, selecting appropriate plants, watering, using alternatives to pesti- cides, and implementing natural lawn care techniques. 2019 Stormwater Management Manual for Western Washington Volume IV - Chapter 4 - Page 526 180/195 ■ Natural Yard Care -Five steps to make your piece of the planet a healthier place to live (King County and SPU, 2008) ■ The Natural Lawn & Garden Series: Smart Watering (Saving Water Partnership, 2006) ■ Natural Lawn Care for Western Washington (Saving Water Partnership, 2007) ■ The Natural Lawn & Garden Series: Growing Healthy Soil; Choosing the Right Plants; and Natural Pest, Weed and Disease Control (Saving Water Partnership, 2012) The International Society of Arboriculture (ISA) is a group that promotes the professional prac- tice of arboriculture and fosters a greater worldwide awareness of the benefits of trees through research, technology, and education. ISA standards used for managing trees, shrubs, and other woody plants are the American National Standards Institute (ANSI) A300 standards. The ANSI A300 standards are voluntary industry consensus standards developed by the Tree Care Industry Association (TC IA) and written by the Accredited Standards Com- mittee (ASC). The ANSI standards can be found on the ISA website: www.isa-arbor.- com/education/publications/index.aspx Washington State University's Gardening in Washington State website at http://garden- ing.wsu.edu contains Washington State specific information about vegetation management based on the type of landscape. See the Pacific Northwest Plant Disease Management Handbook (Pscheidt and Ocamb 2016) for information on disease recognition and for additional resources. 2019 Stormwater Management Manual for Western Washington Volume IV - Chapter 4 - Page 527 181/195 S419 BMPs for Mobile Fueling of Vehicles and Heavy Equipment Description of Pollutant Sources: Mobile fueling, also known as fleet fueling, wet fueling, or wet hosing, is the practice of filling fuel tanks of vehicles by tank trucks that are driven to the yards or sites where the vehicles to be fueled are located. Diesel fuel is categorized as a Class II Combustible Liquid, whereas gasoline is categorized as a Flammable Liquid. Note that some local fire departments may have restrictions on mobile fueling practices. Historically organizations conducted mobile fueling for off -road vehicles operated for extended peri- ods in remote areas. This includes construction sites, logging operations, and farms. Some organ- izations conduct mobile fueling of on -road vehicles commercially in the State of Washington. Pollutant Control Approach: Fueling operators need proper training of fueling operations, the use of spill/drip control, and fuel transfer procedures. Applicable Operational BMPs: Organizations and individuals conducting mobile fueling operations must implement the BMPs in the following list. The operating procedures for the driver/operator should be simple, clear, effective, and their implementation verified by the organization liable for environmental and third party damage. • Ensure that the local fire department approves all mobile fueling operations. Comply with local and Washington State fire codes. . In fueling locations that are in close proximity to sensitive aquifers, designated wetlands, wet- land buffers, or other waters of the State, approval by local jurisdictions is necessary to ensure compliance with additional local requirements. • Ensure compliance with all 49 CFR 178 requirements for all fuel delivery vehicles or con- tainers. Documentation from a Department of Transportation (DOT) Registered Inspector provides proof of compliance. • Ensure the presence and the constant observation/monitoring of the driver/operator at the fuel transfer location at all times during fuel transfer and ensure implementation of the fol- lowing procedures at the fuel transfer locations: 2019 Stormwater Management Manual for Western Washington Volume IV - Chapter 6 - Page 567 182/195 • Locate the point of fueling at least 25 feet from the nearest storm sewer or inside an impervious containment with a volumetric holding capacity equal to or greater than 110 percent of the fueling tank volume, or covering the storm sewer to ensure no inflow of spilled or leaked fuel. Covers are not required for storm sewers that convey the inflow to a spill control separator approved by the local jurisdiction and the fire department. Potential spill/leak conveyance surfaces must be impervious and in good repair. Do not remove the drain cover if sheen is present. Properly collect and dispose of any con- taminated material. • Place a drip pan, or an absorbent pad under each fueling location prior to and during all dispensing operations. The pan (must be liquid tight) and the absorbent pad must have a capacity of at least 5 gallons. There is no need to report spills retained in the drip pan or the pad. • Manage the handling and operation of fuel transfer hoses and nozzle, drip pan(s), and absorbent pads as needed to prevent spills/leaks of fuel from reaching the ground, storm sewer, and receiving waters. • Avoid extending the fueling hoses across a traffic lane without fluorescent traffic cones, or equivalent devices, conspicuously placed to block all traffic from crossing the fuel hose. • Remove the fill nozzle and cease filling the tank when the automatic shut-off valve engages. Do not lock automatic shutoff fueling nozzles in the open position. • Do not "top off' the fuel receiving equipment. Provide the driver/operator of the fueling vehicle with: • Adequate flashlights or other mobile lighting to view fuel fill openings with poor access- ibility. Consult with local fire department for additional lighting requirements. • Two-way communication with his/her home base. . Train the driver/operator annually in spill prevention and cleanup measures and emergency procedures. Make all employees aware of the significant liability associated with fuel spills. . The responsible manager shall properly sign and date the fueling operating procedures. Dis- tribute procedures to the operators, retain them in the organization files, and make them avail- able in the event an authorized government agency requests a review. . Immediately notify the local fire department (911), the appropriate regional office of the Depart- ment of Ecology, and the local jurisdiction in the event of any spill entering surface or ground waters. Establish a "call down list" to ensure the rapid and proper notification of management and government officials should any significant amount of product be lost off -site. Keep the list in a protected but readily accessible location in the mobile fueling truck. The "call down list" should also identify spill response contractors available in the area to ensure the rapid removal of significant product spillage into the environment. . In all fueling vehicles, maintain a minimum of the following spill cleanup materials and have them readily available for use: 2019 Stormwater Management Manual for Western Washington Volume IV - Chapter 6 - Page 568 183/195 • Non -water absorbents capable of absorbing at least 15 gallons of fuel. • A storm drain plug or cover kit. • A non -water absorbent containment boom of a minimum 10 feet in length with a 12-gal- Ion minimum absorbent capacity. • A non -spark generating shovel (a steel shovel could generate a spark and cause an explosion in the right environment around a spill). • Two, five -gallon buckets with lids. • Use automatic shutoff nozzles for dispensing the fuel. Replace automatic shut-off nozzles as recommended by the manufacturer. • Maintain and replace equipment on fueling vehicles, particularly hoses and nozzles, at estab- lished intervals to prevent failures. . Immediately remove and properly dispose of soils with visible surface contamination to pre- vent the spread of chemicals to groundwater or receiving water via stormwater runoff. • Do not use dispersants to clean up spills or sheens unless properly removed for disposal fol- lowing application. Dispersants are prohibited from use for spills on water or where the dis- persant may enter storm drains, surface waters, treatment systems, or sanitary sewers. Applicable Structural Source Control BMPs: Include the following fuel transfer site components: . Automatic fuel transfer shut-off nozzles. . An adequate lighting system at the filling point. 2019 Stormwater Management Manual for Western Washington Volume IV - Chapter 6 - Page 569 184/195 BMP T5.10A: Downspout Full Infiltration Downspout full infiltration systems are trench or drywelI designs intended only for use in infiltrating runoff from roof downspout drains. They are not designed to directly infiltrate runoff from pollutant - generating impervious surfaces. Roof surfaces that comply with this BMP are considered to be "fully infiltrated" (i.e., zero percent effective imperviousness). 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 705 185/195 Procedure for Evaluating Feasibility Have one of the following prepare a soils report to determine if soils suitable for infiltration are present on the site: . A professional soil scientist certified by the Soil Science Society of America (or an equi- valent national program) . A locally licensed on -site sewage designer . A suitably trained person working under the supervision of a professional engineer, geo- logist, hydrogeologist, or engineering geologist registered in the State of Washington. The report shall reference a sufficient number of soils logs to establish the type and limits of soils on the project site. The report should at a minimum identify the limits of any outwash type soils (i.e., those meeting USDA soil texture classes ranging from coarse sand and cobbles to medium sand) versus other soil types and include an inventory of topsoil depth. 2. Complete additional site -specific testing on lots or sites containing outwash (coarse sand and cobbles to medium sand) and loam type soils. Individual lot or site tests must consist of at least one soils log at the location of the infiltration system, a minimum of 4 feet in depth from the proposed grade and at least 1 foot below the expected bottom elevation of the infiltration trench or dry well. Identify the N RCS series of the soil and the USDA textural class of the soil horizon through the depth of the log, and note any evidence of high ground water level, such as mottling. 3. Downspout full infiltration is considered feasible on lots or sites that meet all of the following: . 3 feet or more of permeable soil from the proposed final grade to the seasonal high ground water table. . At least 1-foot of clearance from the expected bottom elevation of the infiltration trench or dry well to the seasonal high ground water table. . The downspout full infiltration system can be designed to meet the minimum design cri- teria specified below. Setbacks Local governments may require specific setbacks in sites with slopes over 40%, land slide areas, open water features, springs, wells, and septic tank drain fields. Adequate room for maintenance access and equipment should also be considered. Examples of setbacks commonly used include the following: 1. All infiltration systems should beat least 10 feet from any structure, property line, or sensitive area (except slopes over 40%). 2. All infiltration systems must beat least 50 feet from the top of any slope over 40%. This set- back may be reduced to 15 feet based on a geotechnical evaluation, but in no instances may it 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 706 186/195 be less than the buffer width. 3. For sites with septic systems, infiltration systems must be downgradient of the drainfield unless the site topography clearly prohibits subsurface flows from intersecting the drainfield. Design Criteria Infiltration Trenches Figure V-4.1: Typical Downspout Infiltration Trench shows a typical downspout infiltration trench sys- tem, and Figure V-4.2: Alternative Downspout Infiltration Trench System for Coarse Sand and Gravel presents an alternative infiltration trench system for sites with coarse sand and cobble soils. These systems are designed as specified below. 1. The following minimum lengths (linear feet) per 1,000 square feet of roof area based on soil type may be used for sizing downspout infiltration trenches: • Coarse sands and cobbles: 20 LF • Medium sand: 30 LF • Fine sand, loamy sand: 75 LF • Sandy loam: 125 LF • Loam: 190 LF 2. Silt and clay type soils have a saturated hydraulic conductivity that is too small for adequate infiltration and are infeasible for downspout infiltration trenches. 3. The maximum length of the trench shall not exceed 100 feet from the inlet sump. 4. The minimum spacing between trench centerlines shall be 6 feet. 5. Filter fabric shall be placed over the drain rock as shown on Figure V-4.1: Typical Downspout Infiltration Trench prior to backfilling. 6. Infiltration trenches may be placed in fill material if: the fill is placed and compacted under the direct supervision of a geotechnical engineer or professional civil engineer with geotechnical expertise, and o the measured infiltration rate is at least 8 inches per hour. Trench length in fill must be 60 linear feet per 1,000 square feet of roof area. Infiltration rates can be tested using the methods described in V-5.4 Determining the Design Infiltration Rate of the Native Soils. 7. Infiltration trenches should not be built on slopes steeper than 25% (4:1). A geotechnical ana- lysis and report may be required on slopes over 15%, or if the proposed trench is located within 200 feet of the top of a slope steeper than 40%, or in a landslide hazard area. 8. Infiltration trenches maybe located under pavement if a small yard drain or catch basin with grate cover is placed at the end of the trench pipe such that overflow would occur out of the 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 707 187/195 Figure V-4.1: Typical Downspout Infiltration Trench Plan Vie i i l -------------- infiltration trench roof drain overflow Profile View 4" rigid or 6" flexible splash block A perforated pipe CB sump w/solid lid 6„ — — — — — — — — — — — — V t 12" washed rock 1 %Z " - 3/4" 1' min ------- 11' min Afine mesh screen varies 10' min. 5' min. Section A -A filter fabric compacted backfill 6" _u 24" 4" rigid or 6" flexible perforated pipe 12" washed rock 1 %Z' - 3/4" 2 NOT TO SCALE Typical Downspout Infiltration Trench Revised June 2016 DEPARTMENT OF ECOLOGYplease see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 709 188/195 Figure V-4.2: Alternative Downspout Infiltration Trench System for Coarse Sand and Gravel Note: Same length dimensions and site limitations as typical system DEPARTMENT OF ECOLOGY State of Washington 2' min. 15' min. Alternative Downspout Infiltration Trench System for Coarse Sand and Gravel Revised June 2016 Please see http://www.ecy.wa.gov/copyrighthtml for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 710 189/195 Infiltration Drywells Figure V-4.3: Typical Downspout Infiltration Drywell shows a typical downspout infiltration drywell system. These systems are designed as specified below. Drywell bottoms must be a minimum of 1 foot above the seasonal high ground water level or impermeable soil layers. 2. When located in course sands and cobbles, drywells must contain a volume of gravel equal to or greater than 60 cubic feet per 1000 square feet of impervious surface served. When loc- ated in medium sands, drywells must contain at least 90 cubic feet of gravel per 1,000 square feet of impervious surface served. 3. Drywells must be at least 48 inches in diameter (minimum) and deep enough to contain the gravel amounts specified above for the soil type and impervious surface served. 4. Filter fabric (geotextile) must be placed on top of the drain rock and on drywell sides prior to backfilling. 5. Spacing between drywells must be a minimum of 10 feet. 6. Downspout infiltration drywells must not be built on slopes greater than 25% (4:1). Drywells may not be placed on or above a landslide hazard area or on slopes greater than 15% without evaluation by a licensed engineer in the state of Washington with geotechnical expertise or a licensed geologist, hydrogeologist, or engineering geologist, and with jurisdiction approval. 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 711 190/195 Figure V-4.3: Typical Downspout Infiltration Drywell Roof House downspout Catch basin (yard drain) flow Roof downspout Plan View Roof downspout House HIV_ --Overflow Splash block flow Fine mesh screen Catch basin (yard drain) 15' min. DEPARTMENT OF ECOLOGY State of Washington Min. 4" dia. PVC pipe Sides of hole lined with filter fabric Section View 48 Inch diameter hole filled with 1 %2 3" washed drain rock / Topsoil Mark center of hole with 1" capped PVC or other means flush with surface 1' min. ooU-c�C�oU-c�C�oO QOo�OQOo�OQO� ( 48 Inch diameter O �( hole filled with 1 y2 4' min. C- 3" washed drain rock QOovOVOovOVO� O Q O Q O Q Min. 1' above seasonal high groundwater table NOT TO SCALE Typical Downspout Infiltration Drywell Revised June 2016 Please see http://www.ecy.wa.govwcopyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 712 191/195 Runoff Model Representation Roof areas served by downspouts that drain to infiltration dry wells or infiltration trenches that are sized in accordance with the guidance in this BMP do not have to be entered into the runoff model. They are presumed to fully infiltrate the roof runoff. 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 713 192/195 BMP T5.13: Post -Construction Soil Quality and Depth Purpose and Definition Naturally occurring (undisturbed) soil and vegetation provide important stormwater functions includ- ing: water infiltration; nutrient, sediment, and pollutant adsorption; sediment and pollutant biofiltra- tion; water interflow storage and transmission; and pollutant decomposition. These functions are largely lost when development strips away native soil and vegetation and replaces it with minimal top soil and sod. Not only are these important stormwater functions lost, but such landscapes them- selves become pollution generating pervious surfaces due to increased use of pesticides, fertilizers and other landscaping and household/industrial chemicals, the concentration of pet wastes, and pol- lutants that accompany roadside litter. Establishing soil quality and depth regains greater stormwater functions in the post development landscape, provides increased treatment of pollutants and sediments that result from development and habitation, and minimizes the need for some landscaping chemicals, thus reducing pollution through prevention. Applications and Limitations Establishing a minimum soil quality and depth is not the same as preservation of naturally occurring soil and vegetation. However, establishing a minimum soil quality and depth will provide improved on -site management of stormwater flow and water quality. Soil organic matter can be attained through numerous materials such as compost, composted woody material, biosolids, and forest product residuals. It is important that the materials used to 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 11- Page 927 193/195 meet this BMP be appropriate and beneficial to the plant cover to be established. Likewise, it is important that imported topsoils improve soil conditions and do not have an excessive percent of clay fines. This BMP can be considered infeasible on till soil slopes greater than 33 percent. Design Guidelines Soil Retention Retain, in an undisturbed state, the duff layer and native topsoil to the maximum extent practicable. In any areas requiring grading, remove and stockpile the duff layer and topsoil on site in a des- ignated, controlled area, not adjacent to public resources and critical areas, to be reapplied to other portions of the site where feasible. Soil Quality All areas subject to clearing and grading that have not been covered by impervious surface, incor- porated into a drainage facility or engineered as structural fill or slope shall, at project completion, demonstrate the following: A topsoil layer with a minimum organic matter content of 10% dry weight in planting beds, and 5% organic matter content in turf areas, and a pH from 6.0 to 8.0 or matching the pH of the undisturbed soil. The topsoil layer shall have a minimum depth of eight inches except where tree roots limit the depth of incorporation of amendments needed to meet the criteria. Subsoils below the topsoil layer should be scarified at least 4 inches with some incorporation of the upper material to avoid stratified layers, where feasible. 2. Mulch planting beds with 2 inches of organic material. 3. Use compost and other materials that meet the following organic content requirements: a. The organic content for "pre -approved" amendment rates can be met only using com- post meeting the compost specification for BMP T7.30: Bioretention, with the exception that the compost may have up to 35% biosolids or manure. The compost must also have an organic matter content of 40% to 65%, and a carbon to nitrogen ratio below 25:1. The carbon to nitrogen ratio may be as high as 35:1 for plantings composed entirely of plants native to the Puget Sound Lowlands region. b. Calculated amendment rates maybe met through use of composted material meeting (a.) above; or other organic materials amended to meet the carbon to nitrogen ratio requirements, and not exceeding the contaminant limits identified in Table 220-B, Test- ing Parameters, in WAC 173-350-220. The resulting soil should be conducive to the type of vegetation to be established. 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 11- Page 928 194/195 Implementation Options The soil quality design guidelines listed above can be met by using one of the methods listed below: 1. Leave undisturbed native vegetation and soil, and protect from compaction during con- struction. 2. Amend existing site topsoil or subsoil either at default "pre -approved" rates, or at custom cal- culated rates based on tests of the soil and amendment. 3. Stockpile existing topsoil during grading, and replace it prior to planting. Stockpiled topsoil must also be amended if needed to meet the organic matter or depth requirements, either at a default "pre -approved" rate or at a custom calculated rate. 4. Import topsoil mix of sufficient organic content and depth to meet the requirements. More than one method may be used on different portions of the same site. Soil that already meets the depth and organic matter quality standards, and is not compacted, does not need to be amended. Planning/Permittinglinspection/Verification Guidelines & Procedures Local governments are encouraged to adopt guidelines and procedures similar to those recom- mended in Building Soil. Guidelines and Resources for Implementing Soil Quality and Depth BMP T5.13 in WDOE Stormwater Management Manual for Western Washington (Stenn et al., 2016). Maintenance • Establish soil quality and depth toward the end of construction and once established, protect from compaction, such as from large machinery use, and from erosion. • Plant vegetation and mulch the amended soil area after installation. • Leave plant debris or its equivalent on the soil surface to replenish organic matter. • Reduce and adjust, where possible, the use of irrigation, fertilizers, herbicides and pesticides, rather than continuing to implement formerly established practices. Runoff Model Representation All areas meeting the soil quality and depth design criteria may be entered into approved runoff mod- els as "Pasture" rather than "Lawn/Landscaping". 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 11- Page 929 195/195 Figure V-11.1: Planting Bed Cross -Section Mulct Loose soil with visible dark organic matter Loose or fractured subsoil Reprinted from Guidelines and Resources For Implementing Soil Quality and Depth BMP T5.13 in WDOE Stormwater Management Manual for Western Washington, 2010, Washington Organic Recycling Council DEPARTMENT OF ECOLOGY State of Washington Planting Bed Cross -Section NOT TO SCALE Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. 2019 Stormwater Management Manual for Western Washington Volume V - Chapter 11- Page 930