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Kentner Residence Drainage Report 06.26.20RESUB Jul 09 2020 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT civil &structural ENGINEERING engineering & planning DRAINAGE REPORT Kentner Residence 806 Cary Road Edmonds, WA 98020 COMPLIES WITH APPLICABLE C 0612612020 CG Project No.: 19387.20 250 411 Ave S Ste 200 Edmonds, WA 98020 Phone: (425)778-8500 Fax: (425) 778-5536 Table of Contents Section I — Project Overview Section II — Off -Site Analysis Section III — Permanent Stormwater Control Plan Section IV —Construction Stormwater Pollution Prevention Plan Section V — Special Reports and/or Studies Section VI — Other Permits Section VII — Bond Quantities & Operation and Maintenance Manual C 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section I, Page 1 Section I — Project Overview Section I Summa Overview Existing Condition Developed Condition Minimum Requirements Overview This drainage report has been written for a re -development of Lot 1 of the Norton Short Plat (AF#201903115001). The existing guest house is being demolished and a new single-family residence is being added in its place. Site Address: 806 Cary Road, Edmonds, WA 98020 Parcel Number: 27032400214000 Zoning: RS-12 Watershed: Shell Creek Watershed In addition to a new house where the guest house used to be, a new porch and a new deck will be added. The existing concrete driveway and asphalt parking area will be replaced. The new house will have roof coverage of approximately 3,465 sf (0.079 ac) and the total new impervious area for the project is approximately 4,958 sf (0.087 ac). Since the project will add less than 5,000 sf of new impervious surfaces, the project is classified as Category 1 per the Edmonds Community Development Code (herein referred to as ECDC) 18.30.060.0 and the June 2017 Addendum to Edmonds Community Development Code Chapter 18.30 (herein referred to as the Edmonds Stormwater Addendum), Chapter 3.1.3.1. Category 1 projects are required to comply with Minimum Requirements #1-5 from ECDC 18.30.060.D and Chapter 5 of the Edmonds Stormwater EMIR C_'iTM0 Existing Condition The existing site is developed with a house and associated walkway and a driveway off Cary Road. Vegetation on -site generally consists of grass, shrubs, and small trees. Site topography descends west to east with an average slope of about 10%, ranging from moderate slopes of 7% to 14% near the rockery at the northeast corner of the site. On average, there is about 9 ft of grade change between the west and east property lines. Although Edmonds GIS Severe Erosion Hazards and Landslide Hazard Areas (see Figure 1-2) depicts the site containing Erosion Hazard the site generally appears to be in stable condition. The geotechnical report by Krazan Associates Inc. dated January 23, 2020 does not recommend on -site infiltration as the PIT test conducted on -site did not yield an infiltration rate due to the low permeability of the underlying soil. According to the geotechnical engineer, the site contains Glacial Till. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section I, Page 2 Other single-family residences border the site on the north south and east sides. No stormwater infrastructure exists within Cary Road. Shell Creek flows east of the neighboring site as well as a wetland in the property to the east. Developed Condition The proposed development is the construction new house on -site, along with a driveway, walkways and a deck and porch. The total of the target impervious area (new and replaced) is 4,958 sf (0.087 ac). Land disturbance will be to the extents of the clearing limits and will be approximately 10,800 sf (see civil plans). The site will utilize a detention pipe to address Minimum Requirement #5: On -Site Stormwater Management. The house's roof drains will be conveyed to the detention pipe, and a trench drain will collect the runoff from the new driveway which will also be directed towards the pipe. A 12" overflow pipe will convey the outlet pipe towards the neighboring storm system. See the civil plans and Section III for more on the Permanent Stormwater Control Plan. The proposed impervious areas were considered as follows: Impervious Areas Roof (with overhang): Walkways (uncovered): Deck: New driveway pavement: New grasscrete (parking): Total: C 4m ENGINEERING 3,465 sf (0.054 ac) 350 sf (0.008 ac) 161 sf (0.004 ac) 614 sf (0.014 ac) 368 sf (0.008 ac) 4,958 sf (0.114 ac) 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section I, Page 3 The new and replaced pollution -generating impervious areas were considered as follows: Pollution -generating Impervious Areas Driveway and grasscrete: 982 sf (0.022 ac) Total: 982 sf (0.022 ac) PROJECT SITE i U OLI EXISTING WATER\ (109 8-52E 8-52D P. 8-239 L 8-52 CO C 4M ENGINEERING ML at[rtae Or x � n A TJ 4. a Caspers St 2 a� 0 Gilmer Ln Sa[er Ln v Hindley Ln arookm ere Or m y Brookmere Or i x 0 E1 Caspers St El n Aioha Way = Aloha st Figure 1-1. Vicinity map (from Google Maps) PROJECT SITE 812 ■ •6 309 SHELL CREEK 730 305 EXISTING SEWER Q Edmonds united Methodist Church Gaspe 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section I, Page 4 Figure 1-2. Map showing existing utilities near site (from City of Edmonds GIS map) r nti Figure 1-3. Aerial image of site (from Google Maps) Minimum Requirements Stormwater requirements were determined per the Edmonds Stormwater Addendum, the ECDC, and Ecology's 2014 Stormwater Management Manual for Western Washington (herein referred to as the SWMMWW). This report is based on the steps outlined in Chapter 3 of Volume I of the SWMMWW and Chapter 7 of the Edmonds Stormwater Addendum. The project is classified as a Category 1 project per Chapter 3.1 of the Edmonds Stormwater Addendum and will comply with Minimum Requirements #1-5 per Figure 1-4 (Figure 3.1 in the Edmonds Stormwater Addendum). Minimum Requirement #1: Preparation of Stormwater Site Plans: The stormwater site plan consists of this report and the civil drawings and is prepared in accordance with Chapter 3 of Volume 1 of the SWMMWW and the requirements in the Edmonds Stormwater Addendum. Minimum Requirement #2: Construction Stormwater Pollution Prevention Plan (SWPPP): The SWPPP shall include a narrative and drawings. The SWPPP narrative shall include documentation that addresses the 13 elements of Construction Stormwater Pollution Prevention. See Section IV and the civil drawings. Minimum Requirement #3: Source Control of Pollution: All known, available and reasonable source control BMPs must be required for all projects approved by the City. All single-family residential projects shall, at a minimum, incorporate required BMPs from SWMMWW Volume IV, S411 — BMPs for C CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section I, Page 5 Landscaping and Lawn/Vegetation Management. The Operation & Maintenance Manual found in Section VII addresses Lawn/Vegetation management. Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls: Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and down gradient properties. All projects shall submit an off -site qualitative analysis. A qualitative analysis of the upstream and downstream system entering the site is presented in Section II. Minimum Requirement #5: On -Site Stormwater Management: The project is a Category 1 project (per Chapter 3.1 of the Edmonds Stormwater Addendum). The project shall either use On -Site Stormwater Management BMPs from List No. 1 for all new plus replaced hard surfaces and land disturbed or demonstrate compliance with the LID Performance Standard. This project will use List No.1 to meet this minimum requirement and provide on -site stormwater management. Post -construction soil quality and depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the SWMMWW will be used for all disturbed pervious areas. A detention pipe will be used for the impervious surfaces, after ruling the BMPs ahead of it on the list to be infeasible. Refer to Section IV of this report. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section I, Page 6 Does the project result in 2,000 square feet, or greater, of new plus replaced hard surface area'? OR Does the land disturbing activity total 7,000 square feet or greater? es Mo Minimum. Requirements No_ 1 through 5 apply I Minimum Requirement No_ 2 applies Next Qnestka Does the project add 5,000 square feet or more of new plus replaced hard surfaces? OR Convert 0.75 acres or more of vegetation to lawn or landscaped areas? OR Convert 2.5 acres or more of native vegetation to pasture? No Yes Is this a road related project? All Minimum Requirements Yes apply to the new and replaced hard surfaces and converted vegetation areas_ .111 Minimum Requirements apply to the new hard surfaces .Ind converted vegetation areas_ No Yes Does the project add 5,000 square feet or No more of new hard surfaces? Yes Do new hard surfaces add 50% or more to the existing hard surfaces within the project limits? No II No additional I requirements_ Figure 1-4. Flow Chart for Determining Minimum Requirements for Development (Figure 3.1 in the Edmonds Stormwater Addendum) C CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section II, Page 1 Section II — Off -Site Analysis Section II Summary Task 1— Define and map the study area Task 2 — Review all available information of the study area Task 3 — Field inspect the area Task 4 - Describe the drainage system, and its existing and predicted problems Task 1— Define and map the study area An initial qualitative analysis shall document potential off -site impacts of stormwater discharges for each upstream drainage system entering a site, and each downstream drainage system leaving a site according to Section 6.2.1 of the Edmonds Stormwater Addendum. The downstream analysis shall extend from the project site to the receiving water, or up to one -quarter mile, whichever is less. Runoff from the site will not enter the City's MS4 within one -quarter mile of the project site. The City's MS4 system is not part of the downstream walk as the natural flow direction is to the east towards the adjacent single-family property to the east. This property to the east contains a wetland and Shell Creek flows to the north along the east property line of this adjacent lot. The receiving water is Shell Creek, which is about 0.08 mi downstream from the site. The downstream flow path is outlined below in Figure II-1 from the City GIS map and Figure II-2 from the Norton Short Plat project. The overall property was developed in 2006 with a guest house and a primary residence. At the time, a yard drain with connection to the site detention was proposed, although this was never constructed. Instead, the existing guest house (806 Cary Road) that is to be removed ties into the downstream roof drains. This connection will be eliminated (See C2.1 of the civil plans). A new pipe will be constructed into the existing storm system on Lot 2 (812 Cary Road). From here, it will connect to the 2006 detention pipe, which then convey to an existing dispersion trench. The trench will need to have its top rock replaced to ensure proper function. From the dispersal trench, the water then sheet flows toward Shell Creek. As easements were not put in place prior to the short platting of the property, a new private storm easement will be required for the project's discharge onto the 812 Cary Road property. Because the property already connects into this property, and the proposed development will necessitate detention, it is expected that flows into the neighboring property will be reduced. C 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section II, Page 2 rLI Figure II-1. Map showing stormwater flow path (from City of Edmonds GIS map) � e K� a uxw �. _ WO r --- � . t ---------=±---- , iv- Hill - All ,'. Lo 1 u nux 12.001 F. v iin` f ` dcai to M 1i"" _yde oed i r S i FNC.A Gr✓ ASE y WOOD Ff710E i� T6 Existing p&fch 4d91n to act as cannedlo 1 point for props i n trench and p top rocks e4 , needs 1 Lo 2 I fOS,O86 .F. L 1A. , �! Ftl6TN64R�ALL NAM LLOG>•vu , 1 1 I WE i7TP s.=. 4 Figure II-2. Map showing markup of Norton Short Plat AF#201903115001 C 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section II, Page 3 Task 2 — Review all available information on the study area Existing stormwater improvements were determined from the survey and the City GIS map. There is no existing drainage infrastructure within Cary Road. The natural direction of flow is to the east towards Shell Creek flowing along the east boundary of the neighboring property. From here Shell Creek flows northwest towards the Puget Sound. According to the City GIS map, the site appears to contain erosion and landslide hazard areas (see Figure II-3 below). The figure depicts that it is severe erosion hazard area with slopes from 15%- 40%. Erosion is not expected to be a problem during the development of the project site as proper drainage will be added and grades will be created to make for flatter areas. Currently there exists wet areas between the two houses, as the 806 Cary Road property does not have catch basins for its surface water. 827 a 8-52E 16 8 52D IQ/ J, I 806 8-239 I.O 8-301 NEIGHBOR WETLAND Figure II-3. Landslide and Erosion Hazard area map (from City of Edmonds GIS map) Task 3 — Field inspect the study area A site visit was done on a cloudy morning with was no rain. From evaluating surrounding conditions, the site does not appear to take on upstream runoff from the surrounding areas. Currently following the natural grade of the slope on -site water sheet flows off the grass onto the neighboring property to the east. Runoff from all impervious areas has been designed to be connected to the proposed house's roof drains or the trench drain in the driveway which will convey runoff to the 36" detention pipe. Stormwater will overflow into the neighboring storm system after detention, where it will then convey to an onsite dispersion trench. The following figures show pictures that were taken on the site visit that show the existing site. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section 11, Page 4 Figure II-4. Existing looped driveway west of the existing house. Figure II-5. Existing house, view from the northwest. C � ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section II, Page 5 Figure II-6. East side of existing house on project site. Figure II-7. Tie into Solid Lid Catch Basin. Round lid in background is from detention system C 4m ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section II, Page 6 Figure II-8. Type I Catch Basin for Existing Dispersion Trench Task 4 — Describe the drainage system, and its existing and predicted problems Existing stormwater improvements were determined from the survey and the City GIS map. Currently no system exists on site. This is causing minor ponding problems between the two properties that are expected to go away upon the installation of a new, tightlined storm system. Downstream of the site is the storm system for lot 2, which includes a detention pipe and dispersal trench. The dispersion trench should be properly maintained to ensure proper outfall of storm drainage from the two properties. Shell Creek less than 0.08 miles to the east. The proposed system will detain the flow within a 36" detention pipe along the north property line of the lot, then connect into the Lot 2 storm system. There are no anticipated problems associated with the development from this project. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section III Page 1 Section III — Permanent Stormwater Control Plan Section III Summary Narrative Narrative The project is classified as a Category 1 project and will comply with Minimum Requirements #1-5 because the project proposes less than 5,000 sf of new/replaced impervious surfaces. The project shall either use On -Site Stormwater Management BMPs from List No. 1 for all new plus replaced hard surfaces and land disturbed or demonstrate compliance with the LID Performance Standard. This project will use List No.1 to determine which On -Site Stormwater Management BMPs area applicable to the site. The proposed impervious areas were considered as follows: Impervious Areas New Roof (with overhang): Walkways (uncovered): Deck: New driveway pavement: New grasscrete (parking): Total: 3,465 sf (0.079 ac) 350 sf (0.008 ac) 161 sf (0.004 ac) 614 sf (0.014 ac) 368 sf (0.008 ad 4,958 sf (0.114 ac) Please note that or determining permit thresholds existing areas need not be considered, but because the runoff will connect to the detention these areas were included in the pipe sizing. Feasibility Review Per ECDC 18.30.060.D.5.b.ii, Category 1 projects that discharge directly or indirectly to the City's MS4 and are required projects that discharges directly to Puget Sound through the City's MS4 must implement BMP T5.13 Post -Construction Soil Quality and Depth and evaluate all BMPs on List No. 1. 1. BMP T5.13 Post -Construction Soil Quality and Depth: Feasible. All new landscaping will meet the Post -Construction Soil Quality and Depth in accordance with BMP T5.13 of the DOE Manual. Roof & Other Hard Surface: 2. BMP T5.10A Downspout Full Infiltration Systems: Infeasible. A full infiltration system is not feasible due to the recommendation of the Geotech consultant as an infiltration rate could not be established as the PIT test conducted on -site did not yield an infiltration rate due to the low permeability of the underlying soil. 3. BMP T5.30 Full Dispersion: Infeasible. Minimum forested or native vegetation flowpath of 100 feet cannot be achieved. 4. Bioretention or Raingarden: Infeasible. Geotech consultant does not recommend infiltration as soils have low permeability and the site slopes towards neighbor's property. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section III Page 2 5. BMP T5.10B Downspout Dispersion Systems: Infeasible. Minimum vegetated flowpath length for splashblocks of 50 feet cannot be met. It may be feasible to meet the requirement for trenches, which have a minimum vegetated flowpath length from outlet to property line, structure, or impervious surface of 25 feet. Due to existing ponding concerns however that need to be addressed and being in an erosion hazard area (see Off Site Analysis, Section 3) , this option was eliminated. 6. BMP T5.10C Perforated Stub -out Connections: Infeasible. Geotech consultant does not recommend infiltration as soils have low permeability and the site slopes towards neighbor's property. 7. Detention Vault or Pipe: Feasible. Please note existing roof area is included in sizing. Per the Edmonds Stormwater Addendum, two detention pipes were sized for length. A 36" diameter pipe was sized using the equation L = 0.008*A, where L is length of pipe (ft) and A is contributing surface area (sf). For the entire contributing impervious area, L = 0.008*(4,958 sf) = 39.6 ft. Therefore, a 36" diameter, 40 ft long detention pipe was selected to mitigate stormwater runoff for the impervious area on -site. C 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section IV, Page 1 Section IV — Construction Stormwater Pollution Prevention Plan Section IV Summarv: Narrative Construction SWPPP Elements Erosion control details are provided consistent with the City of Edmonds guidelines. Erosion control plan sheets are provided in full size as a part of the civil drawing set. A full Construction SWPPP is not required by the Department of Ecology because land -disturbing activity will be under one acre. The remainder of this section is a discussion of the Construction SWPPP Elements per Section 2.5.2 of Volume I of the SWMMWW and the requirements in the Edmonds Stormwater Addendum. See the civil plans for reference. Construction SWPPP Elements The elements for construction pollution prevention are discussed as follows: Element 1: Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land -disturbing activities begin. Clearing limits will be to the extents of necessary land disturbance for the house additions and associated driveway and walkways. The BMPs relevant to marking the clearing limits that will be applied for this project include: High Visibility Plastic or Metal Fence (BMP C103) Element 2: Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads. The proposed driveway area should be used for a stabilized construction entrance to the site. The BMPs relevant to establishing construction access are: Stabilized Construction Entrance (BMP C105) Element 3: Control Flow Rates The site is small enough that a silt fence used for Element 4 may be used to control flow rates. Element 4: Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged. Silt fence will be installed around the perimeter of the site and can be seen on the Temporary Erosion Control Plan, C2.1. Pollution prevention C 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section IV, Page 2 facilities on the erosion control plan must be constructed prior to or in conjunction with all clearing and grading to ensure that the transport of sediment to surface waters and adjacent properties is minimized. The specific BMPs to be used for controlling sediment on this project include: Silt Fence (BMP C233) Element 5: Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: Temporary and Permanent Seeding (BMP C120) Mulching (BMP C121) Nets and Blankets (BMP C122) Plastic Covering (BMP C123) Sodding (BMP C124) Topsoiling/Composting (BMP C125) Surface Roughening (BMP C130) Dust Control (BMP C140) Element 6: Protect Slopes Exposed slopes shall be stabilized with BMPs found in Element 5. Element 7: Protect Drain Inlets No drain inlets exist along Cary Road which is to the west of the property and grade goes towards the east, therefore drain inlets protection is not applicable Element 8: Stabilize Channels and Outlets Conveyance channels are not located on or in the immediate vicinity of the site. Element 9: Control Pollutants Design, install, implement, and maintain effective pollution prevention measures to minimize the discharge of pollutants. The suggested BMPs are: Concrete Handling (BMP C151) Sawcutting and Surfacing Pollution Prevention (BMP C152) Material Delivery, Storage and Containment (BMP C153) Element 10: Control De -Watering De -watering is not anticipated. CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section IV, Page 3 Element 11: Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Element 12: Manage the Project • Phase development projects to the maximum degree practicable and take into account seasonal work limits. • Inspection and monitoring— Inspect, maintain, and repair all BMPs as needed to assure continued performance of their intended function. Conduct site inspections and monitoring in accordance with the Construction Stormwater General Permit or local plan approval authority. • Maintain an Updated Construction SWPPP - This SWPPP shall be retained on -site or within reasonable access to the site. The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. Element 13: Protect Low Impact Development BMPs No Low Impact Development BMPs are proposed for the project. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section V, Page 1 Section V — Special Reports and/or Studies Section V Summary: Narrative The following reports are included in this section: 1. Stormwater Infiltration Study by Krazan and Associates Inc. dated January 23, 2020. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section VI, Page 1 Section VI — Other Permits Section VI Summarv: Narrative Other permits are not anticipated beyond those required by the City of Edmonds. C 4m ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section VI I, Page 1 Section VII — Bond Quantities, Declaration of Covenant, & Operation and Maintenance Manual Section VII Summarv: Narrative The Bond Quantity Worksheet is a standalone document that can also be submitted to the City of Edmonds separately from this document. A Declaration of Covenant is provided for the proposed on -site BMP. The Operation and Maintenance Manual is a standalone document that will be given to the owner(s) following the construction of the project. The maintenance manual contained herein is for the Kentner Residence building project. The contractor will be responsible for the maintenance and operation of all stormwater structures and BMPs requiring maintenance during construction and, after construction, responsibility will pass to the homeowner(s). The project contractor will be responsible for passing along the information in this maintenance manual to the owner(s). Upon request by the City, it shall be made available for their inspection. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com After recording return to: City Clerk City of Edmonds 121 Fifth Avenue North Edmonds, WA 98020 Document Title(s) Declaration of Covenant - Private Stormwater Facility Reference Number(s) of Related Documents City of Edmonds (permit number) Grantor(s) (Last, First and Middle Initial) Grantee(s) (Last, First and Middle Initial) City of Edmonds Legal Description (abbreviated form; i.e., lot, plat or section, township, range, quarter/quarter) See Exhibit A Assessor's Property Tax Parcel/Account Number at the Time of Recording: 27032400214000 The Auditor/Recorder will rely on the information provided on this form. The staff will not read the document to verify the accuracy or completeness of the indexing information provided herein. DECLARATION OF COVENANT Private Stormwater Facility WHEREAS, the undersigned Declarant(s) have installed one or more stormwater facilities under Edmonds Community Development Code Chapter 18.30 known as a "low impact development best management practices (LID BMP)" as selected below: ❑ Permeable Pavement ❑ Infiltration Trench ❑ Rain Garden / Bioretention Cell ❑ Gravelless Chamber ❑ Drywell ❑ Other WHEREAS, the City of Edmonds has allowed installation of the LID BMP, subject to the execution and recording of this Declaration of Covenant; NOW, THEREFORE, THE UNDERSIGNED DECLARANT(S), being the owners of the real property ("the Property") located at the following address: 806 Cary Road in the City of Edmonds, Washington, and legally described on Exhibit A attached hereto and incorporated herein by this reference as if set forth in full, hereby covenants and agrees, on behalf of himself/herself/themselves/itself and his/her/their/its successors and assigns, as follows: Declarant(s) warrant that he/she/they are the owners of the property described on Exhibit A and have the authority to impose this covenant on the property and bind all future owners, successors, and assigns of the Declarant(s). The Declarant(s), future owners, successors, and assigns of the Declarant(s) shall be referred to collectively as "Owners." 2. The Owners of the Property agree that the Property contains one or more stormwater management facilities referred to as an "LID BMP," which was installed to mitigate the stormwater quantity and quality impacts of some or all of the impervious or non-native pervious surfaces on the property. "Low impact development" means development conducted in a way that seeks to minimize or completely prevent alterations to the natural hydrology of the site. Low impact development includes site planning and design to reduce alterations of natural soil and vegetation cover, minimize impervious surfaces, and specific practices that help to replicate natural hydrology such as permeable pavements, green roofs, soil amendments, bioretention systems, and dispersion of runoff. The Owners shall maintain the size, placement, and design of the LID BMP as depicted on the approved site plan, Exhibit B, and design details shall be maintained and may not be changed without written approval either from the Engineering Division of the City of Edmonds or through a future development permit from the City of Edmonds. Chemical fertilizers and pesticides shall not be used where LID BMP is located. All costs of maintenance and repair shall be the sole responsibility of the Owners. 4. The Owners shall inspect LID BMPs annually for physical defects. After major storm events, the system shall also be checked to ensure that the overflow system is working properly. The Owners also shall maintain all LID BMPs so they function as designed on a year-round basis. 5. The City of Edmonds is hereby granted by the Owners the right, but not the obligation, to enter upon the Property described on Exhibit A at all reasonable times for the purpose of inspecting the private stormwater LID BMP facility. If, as the result of any such inspection, the City of Edmonds determines that the LID BMP is in disrepair, requires maintenance or repair, or is otherwise not functioning as provided in the BMP site plan, the City Engineer or his designee shall have the right, but not the obligation, to order the Owners to maintain or repair the same. 6. If the City of Edmonds determines that the LID BMP requires maintenance or repair pursuant to Section 5, the City of Edmonds shall provide notice to the Owners of the deadline within which such maintenance or repair must be completed. Said notice may further advise that, should the violator fail to perform required maintenance or make repairs within the established deadline, the work may be done by the city or a contractor designated by the City Engineer and the expense thereof shall be charged to the Owners. The City's officers, agents, employees, and contractors shall have the right, which is hereby granted by the Owners, to enter upon the Property described on Exhibit A in order to perform such work. The Owners shall bear the cost of all work, performed. 7. The Owners shall indemnify, defend and hold harmless the City of Edmonds, its officers, officials, employees and agents from any and all claims, demands, suits, penalties, losses, damages, judgments, attorneys' fees and/or costs of any kind whatsoever, arising out of or in any way resulting from the approval of the LID BMP(s), the installation and presence of the LID BMP(s), and the acts or omissions of the Owners, their officers, employees, contractors, and agents relating to the construction, operation and maintenance of the LID BMP(s) on the Property, except for the City's intentional and willful tortious acts, and waive and release the City of Edmonds from any and all claims for damages and injunctive relief which the Owners may themselves have now or in the future, by reason of the construction, maintenance and operation of said LID BMP(s). 8. This covenant shall run with the land and be binding upon the Owners. Dated: DECLARANT(S): (Signature) (Print Name) (Signature) (Print Name) State of Washington SS. County of Snohomish APPROVED: CITY OF EDMONDS (Signature) (Print Name) (Title) On this day personally appeared before me {Declarant(s)} to me known to be the individual, or individuals described in and who executed the within and foregoing instrument, and acknowledged that he/she/they signed the same as his/her/their free and voluntary act and deed, for the uses and purposes therein mentioned. SUBSCRIBED AND SWORN before me this day of (Signature) 201 (Name legibly printed or stamped) Notary Public in and for the State of Washington. Residing at: My commission expires Exhibit A Legal description (PER STATUTORY WARRANTY DEED RECORDING #201906200311) LOT 1, CITY OF EDMONDS FINAL SHORT PLAN NO. PLN20170055, RECORDED UNDER RECORIDNG NO. 201903115001, BEING A PORTION OF HE NORTHEAST QUARTER OF THE NORTHWEST QUARTER OF SECITON 24, TOWNSHIP 27 NORTH, RANGE 3 EAST, W.M., RECORDS SNOHOMISH COUNTY, WASHINGTON. r r ID'UTILTTY EASEM ENT ' J FCUUC RE31.R/CA= 10'Pxlb'ATE LT1UY ' ' NOR):ZONEIN 1 ! ,J / / r LSs 3Ua.bq 54'TYPElICS M'N a + EASEMENT SHOULDER-,. u. o-Z'N s N_iJn' �- (j'san: °aa .-iD' ITIU'Y ! ! t /•, /JJ DF PROP :Crt 2 f E1EB'Wj: 399 EASntENT PER Fi ,� ` ! �J f •// �. 3' TCP RISER. 42A SAWCUT 1 /.}� ,_/ J �\ I- ECiN.L RE5nP I / OFTFIITYIN PIPF 'Fi.ZS � %- ?IEWGR/SSCRETE % ` 15 LF6 FVC g�15_GM !\ r ;�� pE:47.4 .4 — %/ —. SJ4' ,—�"'.,�_�"� — ` _ �.'�'' of PROP :OR I 1 M ATC14 EKIYnNGGRADE -,� �, r '%r w4� { 43n^w i- .ai - - •,Ca \ NEW CONCRETE1 / \ -aS4 :— TOP:4O5 ORIJEWAf AY ! ! I TCE:37.8 ( '' \ `�� ''�. ..- �' \�,� ✓ '\,� ��' ' iOP: i 1`'YR�RTOE.- 4�0+0WALL E/OOTNG DRAINS f I }s t . J Sri+ � ',A '`,, .r *��+��, ' • J ..: � �, ,J ' , '•'� t oRran � i � � a I� 'v'TRENCR ATEO I,/ v 9� c: 3 r, 1 J �� ! rN(EW i TRERCN DFAIN I J; I' `� J ` �' ,d. ROOF 490 t - WAL C3c AX 11 T P,IM:47;5 t �ivim...43I r' OR att79 , / ,) W.=.L.. VA% a3.75— — �. j TO Vr NV J iy`o (1 '�DETENT]ON C3_ O a �'f f '1E:dG5 j f TOP.49.0 I .5.: ''C C 1 0, TOE 46_C lO t,y 032 �r <80 r a\., I '' GAR�EEHiRY' SC_24 1 I N=y15nNG DUILDPtr / .. y, ^ ROJ f AND FCOTING '. O ON LRT 2 a,; /L DRtRI I r TOP: 40.5 Q-1 r p�l TCE:37.3 y 1 � F!F I � 1, SIM 483 D [I P E:433 Z l MATCH + 4 (r 4935/ CCNNECTTO EOD. L, � E nsiwG DRAIN GRACE-- i S nPStM}CFII tt. ix r ! 2 ! 1 1 4232 ✓' j a / MAIN FFE 50.2E / 1 D'aMHT:42.32W� f(i 1 +a.3J so.+_4 �— in I , oEc p,�'� �Vu� 2ND STOSYDK3C 1 rO''IERHANG DS / G 70P:p0_5 . U Trrl �9 f 1 �• � �'^-FC'UPT} P< W41L j L r so N%W ER 5C41 j I I NEW CCNSPEE II2 u I°' C,04'V & 0.U%V \ CF P?tIP t:OR t 1 WALL31VAX FOOTING DRAIN C3. 44 ERR SSs _ _ 5t, cFn zrI=-; of :.cecx.7i; TOP:40.5 t — — Gj N 38 �6'57" Y4 I<<^c.18 l — — — — TCE:3z. / i a Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section VII, Page 2 Kentner Residence 806 Cary Road Edmonds, WA 98020 C�I]�I:L��NLIe ►1�10►�ile1l►y��Ie�►L�I�► 1e�►14e1� Date: June 2020 C 4M ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section VI I, Page 3 Operation and Maintenance Manual This Operation and Maintenance Manual has been created for the Kentner Residence: a single-family residence project on a 0.28-acre lot. The proposed storm system consists of a 36" detention pipe with a flow control structure piping stormwater to the downstream lot. Included in this Operation and Maintenance Manual is an 11" x 17" grading and drainage plan sheet showing the location of the detention system. Please note that this map is generated during the design phase and may not reflect all changes made in permitting and construction. CG Engineering may be contacted for an updated copy of this map once the as -built drawings are completed for the site. The contractor will be responsible for the maintenance and operation of all stormwater structures and BMPs requiring maintenance during construction and, after construction, responsibility will pass to the homeowner(s). An aerial image of the project area can be seen on the following page in Figure VII-1. Included in this manual are maintenance sheets taken from the 2014 Stormwater Management Manual for Western Washington for the following facilities/activities: Catch Basins: Concrete structures with steel grates that collect stormwater runoff from the site and act as junctions for storm conveyance pipes. See "No. 5" for maintenance. Trench Drains: Drainage pipes with metal grates crossing driveways to collect stormwater runoff. See "No. 5" for maintenance. Control Structures: Control structures are catch basins or manholes with a restrictor device for controlling outflow from a facility to meet the desired performance. See "No. 4" for maintenance. Closed Detention Systems (Detention Pipes/Tanks): Underground storage facilities typically constructed with large diameter corrugated metal or plastic pipe. See "No. 3" for maintenance. Vegetation Management: Landscaping can include grading, soil transfer, vegetation removal, pesticide and fertilizer applications, and watering. Stormwater contaminants include toxic organic compounds, heavy metals, oils, total suspended solids, coliform bacteria, fertilizers, and pesticides. Facilities shall be inspected for defects listed in the following facility sheets. Most maintenance tasks are generally reactionary to a defect being found, rather than a matter of constant upkeep. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. The facility sheets list the potential conditions warranting maintenance and the expected result following any maintenance. Several engineer's notes for specific tasks are provided within the facility sheets. Unless otherwise noted on the facility sheets the maintenance tasks should be performed on an "as needed" basis: (a) when the described defect is visible to whomever performs the yearly inspection, or (b) should any defect become apparent between inspections. C CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 June 26, 2020 Drainage Report Section VI I, Page 4 Figure VII-1. Aerial image of project area 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Kentner Residence - CG #19387.20 Drainage Report June 26, 2020 Section VI I, Page 5 SAMPLE ACTIVITY LOG DATE FACILITY MAINTENANCE PERFORMED RESULTS / NOTES 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com No. 3 — Closed Detention Systems (Tanks/Vaults) Maintenance Defect Conditions When Maintenance is Needed Results Expected Component When Maintenance is Performed Storage Area Plugged Air Vents One-half of the cross section of a vent is Vents open and blocked at any point or the vent is damaged. functioning. Debris and Sediment Accumulated sediment depth exceeds 10% All sediment and of the diameter of the storage area for 1/2 debris removed from length of storage vault or any point depth storage area. exceeds 15% of diameter. (Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than 1/2 length of tank.) Joints Between Any openings or voids allowing material to All joint between Tank/Pipe Section be transported into facility. tank/pipe sections (Will require engineering analysis to are sealed. determine structural stability). Tank Pipe Bent Out Any part of tank/pipe is bent out of shape Tank/pipe repaired or of Shape more than 10% of its design shape. (Review replaced to design. required by engineer to determine structural stability). Vault Structure Cracks wider than 1/2-inch and any Vault replaced or Includes Cracks in evidence of soil particles entering the repaired to design Wall, Bottom, structure through the cracks, or specifications and is Damage to Frame maintenance/inspection personnel structurally sound. and/or Top Slab determines that the vault is not structurally sound. Cracks wider than 1/2-inch at the joint of any No cracks more than inlet/outlet pipe or any evidence of soil 1/4-inch wide at the particles entering the vault through the walls. joint of the inlet/outlet pipe. Manhole Cover Not in Place Cover is missing or only partially in place. Manhole is closed. Any open manhole requires maintenance. Locking Mechanism Mechanism cannot be opened by one Mechanism opens Not Working maintenance person with proper tools. Bolts with proper tools. into frame have less than 1/2 inch of thread (may not apply to self-locking lids). Cover Difficult to One maintenance person cannot remove lid Cover can be Remove after applying normal lifting pressure. Intent removed and is to keep cover from sealing off access to reinstalled by one maintenance. maintenance person. Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, Ladder meets design misalignment, not securely attached to standards. Allows structure wall, rust, or cracks. maintenance person safe access. Catch Basins See "Catch Basins" See "Catch Basins" (No. 5). See "Catch Basins" (No. 5) (No. 5). Volume V — Runoff Treatment BMPs — December 2014 4-36 No. 4 - Control Structure/Flow Restrictor Maintenance Defect Condition When Maintenance is Needed Results Expected Component When Maintenance is Performed General Trash and Debris Material exceeds 25% of sump depth or 1 Control structure (Includes Sediment) foot below orifice plate. orifice is not blocked. All trash and debris removed. Structural Damage Structure is not securely attached to Structure securely manhole wall. attached to wall and outlet pipe. Structure is not in upright position (allow up Structure in correct to 10% from plumb). position. Connections to outlet pipe are not watertight Connections to outlet and show signs of rust. pipe are water tight; structure repaired or replaced and works as designed. Any holes --other than designed holes --in the Structure has no structure. holes other than designed holes. Cleanout Gate Damaged or Missing Cleanout gate is not watertight or is missing. Gate is watertight and works as designed. Gate cannot be moved up and down by one Gate moves up and maintenance person. down easily and is watertight. Chain/rod leading to gate is missing or Chain is in place and damaged. works as designed. Gate is rusted over 50% of its surface area. Gate is repaired or replaced to meet design standards. Orifice Plate Damaged or Missing Control device is not working properly due to Plate is in place and missing, out of place, or bent orifice plate. works as designed. Obstructions Any trash, debris, sediment, or vegetation Plate is free of all blocking the plate. obstructions and works as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having the Pipe is free of all potential of blocking) the overflow pipe. obstructions and works as designed. Manhole See "Closed See "Closed Detention Systems" (No. 3). See "Closed Detention Systems" Detention Systems" (No. 3). (No. 3). Catch Basin See "Catch Basins" See "Catch Basins" (No. 5). See "Catch Basins" (No. 5). (No. 5). Volume V — Runoff Treatment BMPs — December 2014 4-37 No. 5 — Catch Basins Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash & Trash or debris which is located immediately No Trash or debris located Debris in front of the catch basin opening or is immediately in front of blocking inletting capacity of the basin by catch basin or on grate more than 10%. opening. Trash or debris (in the basin) that exceeds 60 No trash or debris in the percent of the sump depth as measured from catch basin. the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of six inches clearance from the debris surface to the invert of the lowest pipe. Trash or debris in any inlet or outlet pipe Inlet and outlet pipes free blocking more than 1/3 of its height. of trash or debris. Dead animals or vegetation that could No dead animals or generate odors that could cause complaints vegetation present within or dangerous gases (e.g., methane). the catch basin. Sediment Sediment (in the basin) that exceeds 60 No sediment in the catch percent of the sump depth as measured from basin the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of 6 inches clearance from the sediment surface to the invert of the lowest pipe. Structure Top slab has holes larger than 2 square Top slab is free of holes Damage to inches or cracks wider than 1/4 inch and cracks. Frame and/or Top Slab (Intent is to make sure no material is running into basin). Frame not sitting flush on top slab, i.e., Frame is sitting flush on separation of more than 3/4 inch of the frame the riser rings or top slab from the top slab. Frame not securely and firmly attached. attached Fractures or Maintenance person judges that structure is Basin replaced or repaired Cracks in unsound. to design standards. Basin Walls/ Bottom Grout fillet has separated or cracked wider Pipe is regrouted and than 1/2 inch and longer than 1 foot at the secure at basin wall. joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. Settlement/ If failure of basin has created a safety, Basin replaced or repaired Misalignment function, or design problem. to design standards. Vegetation Vegetation growing across and blocking more No vegetation blocking than 10% of the basin opening. opening to basin. Vegetation growing in inlet/outlet pipe joints No vegetation or root that is more than six inches tall and less than growth present. six inches apart. Contamination See "Detention Ponds" (No. 1). No pollution present. and Pollution Volume V — Runoff Treatment BMPs — December 2014 4-38 No. 5 — Catch Basins Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed Catch Basin Cover Not in Cover is missing or only partially in place. Catch basin cover is Cover Place Any open catch basin requires maintenance. closed Locking Mechanism cannot be opened by one Mechanism opens with Mechanism maintenance person with proper tools. Bolts proper tools. Not Working into frame have less than 1/2 inch of thread. Cover Difficult One maintenance person cannot remove lid Cover can be removed by to Remove after applying normal lifting pressure. one maintenance person. (Intent is keep cover from sealing off access to maintenance.) Ladder Ladder Rungs Ladder is unsafe due to missing rungs, not Ladder meets design Unsafe securely attached to basin wall, standards and allows misalignment, rust, cracks, or sharp edges. maintenance person safe access. Metal Grates Grate opening Grate with opening wider than 7/8 inch. Grate opening meets (If Applicable) Unsafe design standards. Trash and Trash and debris that is blocking more than Grate free of trash and Debris 20% of grate surface inletting capacity. debris. Damaged or Grate missing or broken member(s) of the Grate is in place and Missing. grate. meets design standards. No. 6 �—is Barriers (e.g., Trash Racks) Maintenance fect Condition When Maintenance is Results Expec hen Components Needed Maintena s Performed General Trash and Trash or debris that is plugging more B r cleared to design flow Debris n 20% of the openings in the barrier. apacity. Metal Damaged/ Bars a ent out of shape more n 3 Bars in place with no bends more Missing inches. than 3/4 inch. Bars. Bars are miss�en* er Bars in place according to design. missing. are loose and rust is causing % Barrier replaced or repaired to deterioration to any part of barrier. design standards. Inl utlet Debris barrier missing or not attached to er firmly attached to pipe pe pipe Volume V — Runoff Treatment BMPs — December 2014 4-39 Applicable Operational BMPs: • Eliminate unpermitted wastewater discharges to s rm sewer, ground water, or surface water. • Convey unpermitted discharges to a sanitary ewer if allowed by the local sewer authority, or to other approve reatment. Obtain appropriate state and local pe ' s for these discharges. Rec mended Additional Operation BMPs: At commercial and indust ' 1 facilities, conduct a survey wastewater discharge connections to storm ins and to surface wate s follows: • Conduct field survey of bu' dings, particularly older buildings, and other indus ' 1 areas to to to storm drains from buildings and paved surfaces. Note here th e join the public storm drain(s). • During non -storm r conditions inspect each storm drain for non- stormwater dischar e Record the locations of all non-stormwater discharges. Incl e all p itted discharges. • If useful, pre re a map of ch area. Show on the map the known location of orm sewers, sam sewers, and permitted and unpermi d discharges. Aerial p tos may be useful. Check records such a iping schematics to identi own side sewer connections and ow these on the map. Consider 'ng smoke, dye, or chemical an ysis tests to detect connections betw two conveyance systems .g., process water and stormwater). If desi ble, conduct TV inspections of the storm drains and record the otage on videotape. Compare the observed locations of connections th the information on the map and revise the map accordingly. Note s ect connections that are inconsistent with the field survey. • Identify all connections to storm sewers or to surface wa and take the actions specified above as applicable BMPs. S411 BMPs for Landscaping and Lawn/ Vegetation Management Description of Pollutant Sources: Landscaping can include grading, soil transfer, vegetation removal, pesticide and fertilizer applications, and watering. Stormwater contaminants include toxic organic compounds, heavy metals, oils, total suspended solids, coliform bacteria, fertilizers, and pesticides. Lawn and vegetation management can include control of objectionable weeds, insects, mold, bacteria, and other pests with pesticides. Examples include weed control on golf course lawns, access roads, and utility corridors and during landscaping; sap stain and insect control on lumber and logs; rooftop moss removal; killing nuisance rodents; fungicide application to patio decks, and residential lawn/plant care. It is possible to Volume IV - Source Control BMPs — December 2014 2-21 release toxic pesticides such as pentachlorophenol, carbamates, and organometallics to the environment by leaching and dripping from treated parts, container leaks, product misuse, and outside storage of pesticide contaminated materials and equipment. Poor management of the vegetation and poor application of pesticides or fertilizers can cause appreciable stormwater contamination. Pollutant Control Approach: Control of fertilizer and pesticide applications, soil erosion, and site debris to prevent contamination of stormwater. Develop and implement an Integrated Pest Management Plan (IPM) and use pesticides only as a last resort. Carefully apply pesticides/ herbicides, in accordance with label instructions. Maintain appropriate vegetation, with proper fertilizer application where practicable, to control erosion and the discharge of stormwater pollutants. Where practicable grow plant species appropriate for the site, or adjust the soil properties of the subject site to grow desired plant species. Applicable Operational BMPs for Landscaping: • Install engineered soil/landscape systems to improve the infiltration and regulation of stormwater in landscaped areas. Do not dispose of collected vegetation into waterways or storm sewer systems. Recommended Additional Operational BMPs for Landscaping: • Conduct mulch -mowing whenever practicable • Dispose of grass clippings, leaves, sticks, or other collected vegetation, by composting, if feasible. • Use mulch or other erosion control measures on soils exposed for more than one week during the dry season or two days during the rainy season. • Store and maintain appropriate oil and chemical spill cleanup materials in readily accessible locations when using oil or other chemicals. Ensure that employees are familiar with proper spill cleanup procedures. • Till fertilizers into the soil rather than dumping or broadcasting onto the surface. Determine the proper fertilizer application rate for the types of soil and vegetation encountered. • 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. • Use manual and/or mechanical methods of vegetation removal rather than applying herbicides, where practical. Volume IV - Source Control BMPs — December 2014 2-22 Applicable Operational BMPs for the Use of Pesticides: • Develop and implement an IPM (See section on IPM in ,4pplicable e Operational BMPs for Vegetation Manyg ment) and use pesticides only as a last resort. • Implement a pesticide -use plan and include at a minimum: a list of selected pesticides and their specific uses; brands, formulations, application methods and quantities to be used; equipment use and maintenance procedures; safety, storage, and disposal methods; and monitoring, record keeping, and public notice procedures. All procedures shall conform to the requirements of Chapter 17.21 RCW and Chapter 16-228 WAC (Appendix IV-D R.7). • Choose the least toxic pesticide available that is capable of reducing the infestation to acceptable levels. The pesticide should readily degrade in the environment and/or have properties that strongly bind it to the soil. Conduct any pest control activity at the life stage when the pest is most vulnerable. For example, if it is necessary to use a Bacillus thuringiens application to control tent caterpillars, apply it to the material before the caterpillars cocoon or it will be ineffective. Any method used should be site -specific and not used wholesale over a wide area. • Apply the pesticide according to label directions. Do not apply pesticides in quantities that exceed manufacturer's instructions. • Mix the pesticides and clean the application equipment in an area where accidental spills will not enter surface or ground waters, and will not contaminate the soil. • Store pesticides in enclosed areas or in covered impervious containment. Do not discharge pesticide contaminated stormwater or spills/leaks of pesticides to storm sewers. Do not hose down the paved areas to a storm sewer or conveyance ditch. Store and maintain appropriate spill cleanup materials in a location known to all near the storage area. • Clean up any spilled pesticides. Keep pesticide contaminated waste materials in designated covered and contained areas. • The pesticide application equipment must be capable of immediate shutoff in the event of an emergency. • Spraying pesticides within 100 feet of open waters including wetlands, ponds, and rivers, streams, creeks, sloughs and any drainage ditch or channel that leads to open water may have additional regulatory requirements beyond just following the pesticide product label. Additional requirements may include: • Obtaining a discharge permit from Ecology. • Obtaining a permit from the local jurisdiction. • Using an aquatic labeled pesticide. Volume IV - Source Control BMPs — December 2014 2-23 obtain a publication entitled "Suspended, Canceled, and Restricted Pesticides " which lists all restricted pesticides and the specific uses that are allowed. Applicable Operational BMPs for Vegetation Management: Use at least an eight -inch "topsoil" layer with at least 8 percent organic matter to provide a sufficient vegetation -growing medium. Amending existing landscapes and turf systems by increasing the percent organic matter and depth of topsoil can substantially improve the permeability of the soil, the disease and drought resistance of the vegetation, and reduce fertilizer demand. This reduces the demand for fertilizers, herbicides, and pesticides. 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 indefinitely. Select the appropriate turfgrass mixture for the climate and soil type. Certain tall fescues and rye grasses resist insect attack because the symbiotic endophytic fungi found naturally in their tissues repel or kill common leaf and stem -eating lawn insects. However, they do not, repel root -feeding lawn pests such as Crane Fly larvae, and are toxic to ruminants such as cattle and sheep. The fungus causes no known adverse effects to the host plant or to humans. 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 Extension 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: Temporary and Permanent Seeding, Mulching, Plastic Covering, and Sodding as described in Volume II. Adjusting the soil properties of the subject site can assist in selection of desired plant species. For example, design a constructed wetland to resist the invasion of reed canary grass by layering specific strata of organic matters (e.g., composted forest product residuals) and creating a mildly acidic pH and carbon -rich soil medium. Consult a soil restoration specialist for site -specific conditions. • Aerate lawns regularly in areas of heavy use where the soil tends to become compacted. Conduct aeration while the grasses in the lawn are growing most vigorously. Remove layers of thatch greater than 3/4-inch deep. Volume IV - Source Control BMPs — December 2014 2-25 Mowing is a stress -creating activity for turfgrass. Grass decreases its productivity when mown too short and there is less growth of roots and rhizomes. The turf becomes less tolerant of environmental stresses, more disease prone and more reliant on outside means such as pesticides, fertilizers, and irrigation to remain healthy. 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. Irrigation: The depth from which a plant normally extracts water depends on the rooting depth of the plant. Appropriately irrigated lawn grasses normally root in the top 6 to 12 inches of soil; lawns irrigated on a daily basis often root only in the top 1 inch of soil. Improper irrigation can encourage pest problems, leach nutrients, and make a lawn completely dependent on artificial watering. The amount of water applied depends on the normal rooting depth of the turfgrass species used, the available water holding capacity of the soil, and the efficiency of the irrigation system. Consult with the local water utility, Conservation District, or Cooperative Extension office to help determine optimum irrigation practices. Fertilizer Management: Turfgrass is most responsive to nitrogen fertilization, followed by potassium and phosphorus. Fertilization needs vary by site depending on plant, soil, and climatic conditions. Evaluation of soil nutrient levels through regular testing ensures the best possible efficiency and economy of fertilization. For details on soils testing, contact the local Conservation District, a soils testing professional, or a Washington State University Extension office. Apply fertilizers in amounts appropriate for the target vegetation and at the time of year that minimizes losses to surface and ground waters. Do not fertilize when the soil is dry. Alternatively, do not apply fertilizers within three days prior to predicted rainfall. The longer the period between fertilizer application and either rainfall or irrigation, the less fertilizer runoff occurs. Use slow release fertilizers such as methylene urea, IDBU, or resin coated fertilizers when appropriate, generally in the spring. Use of slow release fertilizers is especially important in areas with sandy or gravelly soils. Time the fertilizer application to periods of maximum plant uptake. Ecology generally recommends application in the fall and spring, although Washington State University turf specialists recommend four fertilizer applications per year. Volume IV - Source Control BMPs — December 2014 2-26