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APPROVED STM BLD2020-1033+Storm_Drainage_Report+3.8.2021_4.10.37_PM+2081732Johannessen Short Plat Lot 1 10731 2261" Street SW Edmonds, WA 98020 Storm Drainage Report Prepared for: Leif Helleren Date: September 15, 2020 Revised: February 23, 2021 APPLIES WITH APPLICABLE CITY STROMWATER CODE 36508W� ��GISTEg� \j0NA1 ,� Prepared by: Rob Long, PE RAM Enrlinpering, Inr- 16531 13t" Ave W, Suite A108, Lynnwood WA 98037 (425) 678-6960 RAMengineeringinc.corn RESUB Mar 09 2021 CITV OF EDMONDS DEVELOPMENTSERVICES DEPARTMENT Job No. 17-002 Lot 1 of Johannessen Short Plat 10731 226th Street SW Edmonds, WA 98020 Introduction: This summary report provides site design information for a lot 1 of the Johannessen 3-lot short. This report includes storm drainage analysis to support the building permit review and approval. The property is located on the north side of 226th St SW and east 108th Ave W (N Deer Dr), in the southwest 1/4 of Section 25, T 27 N, R 3 E, W.M. Site Address: 10731 226th Street SW Applicant: Leif Helleren Edmonds, WA 98020 P.O. Box 1764 Edmonds, WA 98020 Tax Parcel Number: 270325-002-035-00 (new parcel to be assigned by Sno Co.) TABLE OF CONTENTS SECTION PAGES A. Project Summary............................................................................................................................... 3 B. Parcel (Vicinity) Map.......................................................................................................................... 1 C. Site Plan............................................................................................................................................. 2 D. Aerial Photo....................................................................................................................................... 1 E. Stormwater Control System Summary............................................................................................. 15 F. Drainage Basin Description and Maps............................................................................................... 3 G. Grading and Erosion Control Summary (SWPPP Evaluation)............................................................ 3 H. Operation and Maintenance Guidelines.......................................................................................... 10 I. Geotechnical Engineering Report.................................................................................................... 14 R.4MEngineering, Inc. Final Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page A. PROJECT SUMMARY: This report provides engineering information for the proposed construction a single family residence on Lot 1 of the Johannessen short plat located at 10727 226th St SW in the City of Edmonds. Existing Conditions. Lot 1 of the Johannessen short plat consists of about 16,856 sf (0.387 acres) and is currently a vacant lot of the short plat. The site is surrounded by large -lot single family residences to the north, west, and east; and 226th St SW to the south (see attached aerial photo- section D). The site has a large sloping bank along the site's west and northerly boundary; the bank drops about 18 feet and slopes in a southeasterly direction; the center and southeasterly lower pad area is generally flat (+/-2%) and slopes in a south/southeast direction towards 226th St SW. The site's drainage runoff would sheet flow south/southeasterly direction towards 226th St SW. No stream or wetlands were discovered on or immediately adjacent to the site; Deer Creek is located about 900 feet south of the site. Additional discussion of the local drainage basin and downstream path is discussed in section F of this report. Developed Conditions. The proposed project includes the construction of single residence and associated driveway and utilities. The lot will utilize a shared access driveway apron off of 2261h St SW for access with Lot 2 (East of the site) of the short plat. New infrastructure improvements include a stormwater conveyance and separate infiltration trench/dry well; water; sewer; power; and communications. The individual lot infiltration trench/dry well system is designed and sized to provide 100% infiltration of the project's hard surfaces and meet compliance with the LID performance standard of the Edmonds Community Development Code (ECDC). All disturbed pervious (lawn and landscape) areas will preserve or restore the health and water -holding capacity of the soils by compost -amending (Per DOE BMP T5.13: Post -Construction Soil Quality and Depth). Due to the fact, the pollution generating driveway area is less than 5,000 sf (2,925 sf) no water quality treatment system will be provided. A full overview of the proposed storm drainage control facilities, offsite/downstream analysis and grading and erosion control measures are discussed in the following sections of this report. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page A-1 Summary of Minimum Requirements for Category 2 Project: 5.1 Minimum Requirement #1—preparation of Stormwater Site Plan. The proposed Lot 1 site development is part of a larger short plat development that will be creating/replacing about 16,650 sf of hard surface area. Thus, the project is classified as a Category 2 project per the City's classification system. The civil site development plans and this report have been prepared to address the projects impacts. 5.2 Minimum Requirement #2 — Construction Stormwater Pollution Prevention. A construction Stormwater Pollution Prevention Plan (SWPPP) has be incorporated into the site development plans. A summary of the site's erosion control measures that evaluates the typical 13 elements of a SWPPP are included in section G. The total site disturbance area of the project is less than one acre, thus a formal Notice of Intent application for NPDES coverage will not be made to the Department of Ecology. 5.3 Minimum Requirement #3 — Source Control of Pollution. Specific source controls are not required for single family residential sites. General requirements for these sites include preventing the discharge of pollutants to the City's storm drainage system per Edmonds City Code Chapter 7.200 (Illicit Discharges). This includes common household items such as pesticides, herbicides, fertilizers, detergents and fluids from vehicle maintenance. Single family residences shall incorporate DOE's S411 BMPs for landscape and lawn vegetation management. 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 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. 5.4 Minimum Requirement #4 — Preservation of Natural Drainage Systems and Outfalls. The site does not have a defined discharge location and due to the underlying outwash soils, it is believed a majority of the stormwater runoff dissipates/infiltrates prior to leaving the site. The proposed project will utilize infiltration trench/ dry well to mitigate new hard surfaces, no outfall discharge point is proposed. The site is located within the Deer Creek watershed basin and eventually discharge to the Puget Sound (via Deer Creek) per the City of Edmonds maps (see section F). 5.5 Minimum Requirement #5 — Onsite Stormwater Management. The developed site conditions include new/replaced hard surface for the roof top, driveway and walkway/patio areas for the proposed residence. All rooftop and exterior area collection drains shall convey stormwater run-off to the on -site infiltration trench/dry well system on the lot. The individual lot infiltration trench/dry well system has been designed and sized to meet compliance with the LID performance standard (MR #5) of the Edmonds Community Development Code (ECDC). Additionally, all disturbed pervious (lawn and landscape) areas will preserve or restore the health and water -holding capacity of the soils by compost -amending (Per DOE BMP T5.13: Post - Construction Soil Quality and Depth). See civil site development plans and section E for additional sizing calculations and construction details. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page A-2 5.6 Minimum Requirement #6 — Runoff Treatment. The project does not propose to create/replace more than 5,000 sf of pollution -generating impervious surface onsite. The project will create about 2,925 sf of pollution generating hard surfaces (driveway); most the site's hard surface is rooftop and walkway/patio areas (non -pollution generating surfaces). Thus, no basic or enhanced water quality treatment system is required. The site's stormwater control system will include a sump and a floatable tee that will provide some water quality and oil/water separation of the collected runoff. 5.7 Minimum Requirement #7— Flow Control. An infiltration trench/dry well will provide flow control of the site's stormwater runoff. The infiltration trench/dry well shall meet the flow control standards of a Category 2 project in a creek or lake basin and meet full flow control (due to the fact the total short plat project proposes more than 10,000 sf of hard surface area). The individual lot stormwater infiltration system is designed to fully mitigate the increased hard surfaces and be in full compliance with the LID Standard and full flow control (match flow durations between 8 percent of the 2-year flow through the full 50-year flow). 5.8 Minimum Requirement #8— Wetland Protection. No wetlands are known to exist on or adjacent to the site. 5.9 Minimum Requirement #9 —Operation and Maintenance. An operation and maintenance summary is provided in section H. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page A-3 B. SHORT PLAT PARCEL (VICINITY) MAP OW9ITER I SECTION I TOWNSHIP N.W BL I RANGEEMM. SW 25 27 3 G - G__ Lot , c: — erlerlln. .. .. ITorA 6eceon - � — � TY Lan1O I Gov Lot Sub*v — ROW — OuarW Tex Acot "' I-- • • ....` lure-2NfM Major VWNr — Other lot --- Vac ROW ---- tern Easerr'" ...........: A),r•/•tlyrk Aax..w;Op7re - ' =!I"'��rtAwMt4 Nfl .9—i."A Ce•M1 mk4j.0 w Minor W01er Other SuDEiv — Vac Lot i NW,26.274N ._ Ulm 00 I PARK 7 Ot s r _ 2.148 I.,. Z r' 7 KI RESERVOIR RESER'Jk �ELM-WAY--.._.I 02 I t =7CONDOMINIUM N D,otPtotl£i2.149 If ---� n 9 PPN1 4 i3 .� •a-@i'S(8383) PA iN ) a 1 OD IJ Ol t4 17 12 9 10 �`---1 --- M 3i ---- — 220TFr--SF__c,,yy_ ¢' 3012 xt 22,.. 9 �' �M VIEA D e B t ¢ 1W Ls 3-001 - - -- x 1e 3 4 2 yprqt 27 t I 1 2 VI 3 y i o 4 ' zs °' 2a 17 . ELM . 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( < 03 1I 2 01 sP 7 a I tOB1 NW46.27-03 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page B-1 C. SHORT PLAT SITE PLAN �Af£X NIXNAR / // UNPLATTEO i ------------ AFN \ (crR.aal r PAEL T `C^ I ! I / /' ��'f',•t�� /'%���f ��/ I � \\��'a® � �Cj � `Caw'esr i----- \/ J ' psi x vrJ i o tF alJ,,' I ie3 ASSESSOR'S PLAT 0 ;; Epp xo� OF NOOONAY PARK I �A_i/ / ' y♦1 1 '/—� 1 r�® rwUsc oK'1or AFN 20050f0450O2 �I 0 YYY / //r� / 9a �t'F\ ioor �wwww//accrrU lJ 12 / ✓ a�zr� rARPiucJ N. mu zr�w61 \ \ /gyp rv� f---- _i_ �\ \ hM1 i i mcposco ra I ___ Ccm crrarvrves) \ .•P _ -snnxs MVAT / J l c smc r �! --ssco __- X M7 i ` 1 g i �� - II !I li Nn �l F----------. � II /✓ / ,\ _ . sas e sswn K-� / A I l � »tsne. x a eumsu / \, fd]H9ry GSEMENr I / I I �n II SNO PLAr$-2009 • }55 \---_-_____-__ p I / I IIN 1 AINTOOS0104500T �' /// rd• ry I 2 T , _ _ L -- - wsrun,�araau�r y i ____________ ________J ' —'—fsE orrAu av sir or-arl Inns cwr _'/z" '° r----I ' l wArcR ___ ior�elieor r r-r/z' wnn ! I 1 w mr __ urury eager tow;certav �. frs%u�mRr'' zss siu - - -'-'---_,-=� ---� fcors a?1 an �.saxcv me E✓<hiRt�AUP �.- � �c RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page C-1 LOT 1 SITE PLAN: -_ RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 ------ -- Johannessen Short Plat Lot 1 #10731 226t" St SW Page C-2 D. SHORT PLAT AERIAL PHOTO (City of Edmonds GIS, 2015 photo) RAM =ngineering, Inc. Engineering and Drainage Report RAM No. 17-002 a.aa� •f r Johannessen Short Plat Lot 1 #10731 226t" St SW 0. Page D-1 E. STORMWATER CONTROL SYSTEM SUMMARY AND CALCULATIONS: The project development of Lot 1 will create 5,860 sf of hard surface. The hard surface areas include the roof top, driveway, walk/patio areas together with 50% of the shared driveway access apron off 226t" St SW. To mitigate the development of the site, an individual lot infiltration trench/drywell system will be installed to control the drainage runoff (flow control). The project applicant has elected to meet the LID Performance Standard to comply with ECDC 18.30.060.D.b (ii) and (iii), stormwater discharges shall match developed discharge durations to pre -developed durations for the range of pre -developed discharge rates from 8 percent of the 2-year peak flow to 50 percent of the 2-year peak flow from the project site. Additionally, the project will meet Minimum Requirement No. 7 and match flow durations between 8 percent of the 2-year flow through the full 50-year flow. The following is a summary of the Lot 1 hard surface areas: Lot 1 Hard Surface Summary: House = 2,785 sf Driveway = 2,600 sf Walk/Patio = 150 sf 50% 226t" St SW Frontage Apron = 325 sf Lot 1 Hard Surface = 5,860 sf (0.135 ac) A site specific geotechnical evaluation was made to assess the use of infiltration and LID measures onsite. The evaluation determined infiltration is feasible onsite and recommends a long-term infiltration design rate of 18.0 in/hr. The infiltration trench/dry well will be located at the southerly portion of Lot 1. The infiltration trench shall be a minimum of 7 feet wide, 20 feet long and 2.5 feet deep; and filled with %" to 1-%" washed drain rock (35% voids). The below calculations demonstrate that the trench will fully mitigate the increased hard surfaces and the project will be in full compliance with the LID Standard and full flow control (match flow durations between 8 percent of the 2-year flow through the full 50-year flow). The developed runoff rates and storage calculations were performed using the DOE 2012 Western Washington Hydrology Model (WWHM2012) continuous runoff model. See WWHM2012 printout on the following pages. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page E-1 F170E Tue 10:06a Ej Gravel Trench Bed 1 Mitigated Facility Name Downstream Connection Facility Type r Precipitation Applied to Facility r :Evaporation Applied to Facility Gravel Trench Bed 1 Outlet 1 Outlet 2 Outlet 3 0 10 10 Gravel Trench/Bed Quick Trench I Facility Dimension Diagram Facility Dimensions Trench Length (ft) Trench Bottom Width (ft) Effective Total Depth (ft) 25 Top and bottom slope (HN) 0 Left Side Slope (HN) 0 Right Side Slope (HN) 0 Material Layers for Trench/Bed Layer 1 Thickness (ft) 2.5 Layer 1 porosity (0.1) 0.3g Layer 2 Thickness (ft) 0 Layer 2 porosity (0.1) 0 Layer 3 Thickness (ft) 0 Layer 3 porosity (0.1) 0 Infiltration Yes Measured Infiltration Rate (in/hr) 18 J Reduction Factor (infilt"factor) Fi- - Use Wetted Surface Area (sidewalls) NO J Total Volume Infiltrated (ac-ft) 49.117 Total Volume Through Riser (ac-ft) 0 Size Infiltration Trench Target %• 100 --H WWHM2012 PROJECT REPORT Project Name: Johannessen Lot 1 Site Name: Johannessen Site Address: 17-002 City : Edmonds Report Date: 9/15/2020 MGS Regoin Puget East Data Start 1901/10/1 Data End : 2058/09/30 DOT Data Number: 03 Version Date: 2019/09/13 Version : 4.2.17 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Outlet Structure Data Riser Height (ft) lu — Riser Diameter (in) FO Riser Type Flat Notch Type Orifice Diameter Height Number (in) (ft) 1 Fo----H F 2 ro--- --! Fo-- : { 3 Fo--- --L-1 Fo-- .J Trench Volume at Riser Head (ac-ft) .003 Show Trench 10pen Table ={ Initial Stage (ft) 0 Total Volume ThroughFaarty act 49.117 Percent Infiltrated 100 Johannessen Short Plat Lot 1 #10731 226th St SW Page E-2 Low Flow Threshold for POC 1 : 50 Percent of the 2 Year High Flow Threshold for POC 1: 50 year PREDEVELOPED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Steep .135 Pervious Total 0.135 Impervious Land Use acre Impervious Total 0 Basin Total 0.135 Element Flows To: Surface Interflow MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 0.064 DRIVEWAYS FLAT 0.068 SIDEWALKS FLAT 0.003 Impervious Total 0.135 Basin Total 0.135 Element Flows To: Groundwater Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-3 Name : Gravel Trench Bed 1 Bottom Length: 20.00 ft. Bottom Width: 7.00 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: 2.5 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 Infiltration On Infiltration rate: 18 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 49.117 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 49.117 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 0 ft. Riser Diameter: 0 in. Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.003 0.000 0.000 0.000 0.0278 0.003 0.000 0.000 0.058 0.0556 0.003 0.000 0.000 0.058 0.0833 0.003 0.000 0.000 0.058 0.1111 0.003 0.000 0.000 0.058 0.1389 0.003 0.000 0.000 0.058 0.1667 0.003 0.000 0.000 0.058 0.1944 0.003 0.000 0.000 0.058 0.2222 0.003 0.000 0.000 0.058 0.2500 0.003 0.000 0.000 0.058 0.2778 0.003 0.000 0.000 0.058 0.3056 0.003 0.000 0.000 0.058 0.3333 0.003 0.000 0.000 0.058 0.3611 0.003 0.000 0.000 0.058 0.3889 0.003 0.000 0.000 0.058 0.4167 0.003 0.000 0.000 0.058 0.4444 0.003 0.000 0.000 0.058 0.4722 0.003 0.000 0.000 0.058 0.5000 0.003 0.000 0.000 0.058 0.5278 0.003 0.000 0.000 0.058 0.5556 0.003 0.000 0.000 0.058 0.5833 0.003 0.000 0.000 0.058 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-4 0.6111 0.003 0.000 0.000 0.058 0.6389 0.003 0.000 0.000 0.058 0.6667 0.003 0.000 0.000 0.058 0.6944 0.003 0.000 0.000 0.058 0.7222 0.003 0.000 0.000 0.058 0.7500 0.003 0.000 0.000 0.058 0.7778 0.003 0.000 0.000 0.058 0.8056 0.003 0.000 0.000 0.058 0.8333 0.003 0.000 0.000 0.058 0.8611 0.003 0.001 0.000 0.058 0.8889 0.003 0.001 0.000 0.058 0.9167 0.003 0.001 0.000 0.058 0.9444 0.003 0.001 0.000 0.058 0.9722 0.003 0.001 0.000 0.058 1.0000 0.003 0.001 0.000 0.058 1.0278 0.003 0.001 0.000 0.058 1.0556 0.003 0.001 0.000 0.058 1.0833 0.003 0.001 0.000 0.058 1.1111 0.003 0.001 0.000 0.058 1.1389 0.003 0.001 0.000 0.058 1.1667 0.003 0.001 0.000 0.058 1.1944 0.003 0.001 0.000 0.058 1.2222 0.003 0.001 0.000 0.058 1.2500 0.003 0.001 0.000 0.058 1.2778 0.003 0.001 0.000 0.058 1.3056 0.003 0.001 0.000 0.058 1.3333 0.003 0.001 0.000 0.058 1.3611 0.003 0.001 0.000 0.058 1.3889 0.003 0.001 0.000 0.058 1.4167 0.003 0.001 0.000 0.058 1.4444 0.003 0.001 0.000 0.058 1.4722 0.003 0.001 0.000 0.058 1.5000 0.003 0.001 0.000 0.058 1.5278 0.003 0.001 0.000 0.058 1.5556 0.003 0.001 0.000 0.058 1.5833 0.003 0.001 0.000 0.058 1.6111 0.003 0.001 0.000 0.058 1.6389 0.003 0.001 0.000 0.058 1.6667 0.003 0.001 0.000 0.058 1.6944 0.003 0.001 0.000 0.058 1.7222 0.003 0.001 0.000 0.058 1.7500 0.003 0.002 0.000 0.058 1.7778 0.003 0.002 0.000 0.058 1.8056 0.003 0.002 0.000 0.058 1.8333 0.003 0.002 0.000 0.058 1.8611 0.003 0.002 0.000 0.058 1.8889 0.003 0.002 0.000 0.058 1.9167 0.003 0.002 0.000 0.058 1.9444 0.003 0.002 0.000 0.058 1.9722 0.003 0.002 0.000 0.058 2.0000 0.003 0.002 0.000 0.058 2.0278 0.003 0.002 0.000 0.058 2.0556 0.003 0.002 0.000 0.058 2.0833 0.003 0.002 0.000 0.058 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-5 2.1111 0.003 0.002 0.000 0.058 2.1389 0.003 0.002 0.000 0.058 2.1667 0.003 0.002 0.000 0.058 2.1944 0.003 0.002 0.000 0.058 2.2222 0.003 0.002 0.000 0.058 2.2500 0.003 0.002 0.000 0.058 2.2778 0.003 0.002 0.000 0.058 2.3056 0.003 0.002 0.000 0.058 2.3333 0.003 0.002 0.000 0.058 2.3611 0.003 0.002 0.000 0.058 2.3889 0.003 0.002 0.000 0.058 2.4167 0.003 0.002 0.000 0.058 2.4444 0.003 0.002 0.000 0.058 2.4722 0.003 0.002 0.000 0.058 2.5000 0.003 0.002 0.000 0.058 ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.135 Total Impervious Area:O Mitigated Landuse Totals for POC #1 Total Pervious Area:O Total Impervious Area:0.135 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000085 5 year 0.000102 10 year 0.00011 25 year 0.000117 50 year 0.000121 100 year 0.000125 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Stream Protection Duration RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-6 Annual Peaks for Predeveloped and Mitigated 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 0.003 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 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 POC #1 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-7 1954 0.000 0.000 1955 0.000 0.000 1956 0.000 0.000 1957 0.000 0.000 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 0.053 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 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-8 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 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 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-9 Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated Rank Predeveloped Mitigated 1 0.0001 0.0532 2 0.0001 0.0031 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 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 POC #1 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-10 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 57 0.0001 0.0000 58 0.0001 0.0000 59 0.0001 0.0000 60 0.0001 0.0000 61 0.0001 0.0000 62 0.0001 0.0000 63 0.0001 0.0000 64 0.0001 0.0000 65 0.0001 0.0000 66 0.0001 0.0000 67 0.0001 0.0000 68 0.0001 0.0000 69 0.0001 0.0000 70 0.0001 0.0000 71 0.0001 0.0000 72 0.0001 0.0000 73 0.0001 0.0000 74 0.0001 0.0000 75 0.0001 0.0000 76 0.0001 0.0000 77 0.0001 0.0000 78 0.0001 0.0000 79 0.0001 0.0000 80 0.0001 0.0000 81 0.0001 0.0000 82 0.0001 0.0000 83 0.0001 0.0000 84 0.0001 0.0000 85 0.0001 0.0000 86 0.0001 0.0000 87 0.0001 0.0000 88 0.0001 0.0000 89 0.0001 0.0000 90 0.0001 0.0000 91 0.0001 0.0000 92 0.0001 0.0000 93 0.0001 0.0000 94 0.0001 0.0000 95 0.0001 0.0000 96 0.0001 0.0000 97 0.0001 0.0000 98 0.0001 0.0000 99 0.0001 0.0000 100 0.0001 0.0000 101 0.0001 0.0000 102 0.0001 0.0000 103 0.0001 0.0000 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-11 104 0.0001 0.0000 105 0.0001 0.0000 106 0.0001 0.0000 107 0.0001 0.0000 108 0.0001 0.0000 109 0.0001 0.0000 110 0.0001 0.0000 111 0.0001 0.0000 112 0.0001 0.0000 113 0.0001 0.0000 114 0.0001 0.0000 115 0.0001 0.0000 116 0.0001 0.0000 117 0.0001 0.0000 118 0.0001 0.0000 119 0.0001 0.0000 120 0.0001 0.0000 121 0.0001 0.0000 122 0.0001 0.0000 123 0.0001 0.0000 124 0.0001 0.0000 125 0.0001 0.0000 126 0.0001 0.0000 127 0.0001 0.0000 128 0.0001 0.0000 129 0.0001 0.0000 130 0.0001 0.0000 131 0.0001 0.0000 132 0.0001 0.0000 133 0.0001 0.0000 134 0.0001 0.0000 135 0.0001 0.0000 136 0.0001 0.0000 137 0.0001 0.0000 138 0.0001 0.0000 139 0.0001 0.0000 140 0.0001 0.0000 141 0.0001 0.0000 142 0.0001 0.0000 143 0.0001 0.0000 144 0.0001 0.0000 145 0.0001 0.0000 146 0.0001 0.0000 147 0.0001 0.0000 148 0.0001 0.0000 149 0.0001 0.0000 150 0.0001 0.0000 151 0.0001 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 RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-12 Stream Protection Duration POC #1 The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0000 6397 0 0 Pass 0.0000 6204 0 0 Pass 0.0000 5956 0 0 Pass 0.0000 5747 0 0 Pass 0.0000 5505 0 0 Pass 0.0000 5333 0 0 Pass 0.0000 5155 0 0 Pass 0.0000 5005 0 0 Pass 0.0000 4830 0 0 Pass 0.0000 4708 0 0 Pass 0.0001 4568 0 0 Pass 0.0001 4426 0 0 Pass 0.0001 4330 0 0 Pass 0.0001 4197 0 0 Pass 0.0001 4089 0 0 Pass 0.0001 3983 0 0 Pass 0.0001 3875 0 0 Pass 0.0001 3771 0 0 Pass 0.0001 3672 0 0 Pass 0.0001 3561 0 0 Pass 0.0001 3439 0 0 Pass 0.0001 3340 0 0 Pass 0.0001 3210 0 0 Pass 0.0001 3105 0 0 Pass 0.0001 3033 0 0 Pass 0.0001 2939 0 0 Pass 0.0001 2857 0 0 Pass 0.0001 2770 0 0 Pass 0.0001 2665 0 0 Pass 0.0001 2574 0 0 Pass 0.0001 2474 0 0 Pass 0.0001 2392 0 0 Pass 0.0001 2311 0 0 Pass 0.0001 2197 0 0 Pass 0.0001 2110 0 0 Pass 0.0001 2036 0 0 Pass 0.0001 1965 0 0 Pass 0.0001 1879 0 0 Pass 0.0001 1814 0 0 Pass 0.0001 1753 0 0 Pass 0.0001 1657 0 0 Pass 0.0001 1576 0 0 Pass 0.0001 1470 0 0 Pass 0.0001 1436 0 0 Pass 0.0001 1352 0 0 Pass 0.0001 1300 0 0 Pass RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-13 0.0001 1237 0 0 Pass 0.0001 1179 0 0 Pass 0.0001 1142 0 0 Pass 0.0001 1103 0 0 Pass 0.0001 1047 0 0 Pass 0.0001 989 0 0 Pass 0.0001 945 0 0 Pass 0.0001 904 0 0 Pass 0.0001 872 0 0 Pass 0.0001 842 0 0 Pass 0.0001 810 0 0 Pass 0.0001 792 0 0 Pass 0.0001 747 0 0 Pass 0.0001 715 0 0 Pass 0.0001 688 0 0 Pass 0.0001 658 0 0 Pass 0.0001 617 0 0 Pass 0.0001 594 0 0 Pass 0.0001 570 0 0 Pass 0.0001 553 0 0 Pass 0.0001 533 0 0 Pass 0.0001 488 0 0 Pass 0.0001 435 0 0 Pass 0.0001 397 0 0 Pass 0.0001 371 0 0 Pass 0.0001 343 0 0 Pass 0.0001 307 0 0 Pass 0.0001 259 0 0 Pass 0.0001 223 0 0 Pass 0.0001 200 0 0 Pass 0.0001 185 0 0 Pass 0.0001 155 0 0 Pass 0.0001 114 0 0 Pass 0.0001 98 0 0 Pass 0.0001 61 0 0 Pass 0.0001 44 0 0 Pass 0.0001 29 0 0 Pass 0.0001 14 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 3 0 0 Pass 0.0001 2 0 0 Pass 0.0001 2 0 0 Pass 0.0001 2 0 0 Pass 0.0001 2 0 0 Pass RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226t" St SW Page E-14 Water Quality BMP Flow and Volume for POC #1 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 Treatment Facility (ac-ft) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Gravel Trench Bed 1 POC ❑ 44.70 ❑ 100.00 Total Volume Infiltrated 44.70 0.00 0 00 100.00 0.00 0% No Treat. Credit Compliance with LID Duration Standard S% of 2-yr to 50% of Analysis 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. 2005-2020; All Rights Reserved. RAM Engineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226th St SW Page E-15 F. DRAINAGE BASIN DESCRIPTION: The site is located within the City of Edmonds Deer Creek watershed basin. The Deer Creek basin is an urban basin that collects stormwater runoff from primarily residential areas in the City Edmonds and ultimately discharges flows westerly to Puget Sound via the Deer Creek (see attached watershed map). Soils in the area consists of well -draining outwash soils that allows a majority of the stormwater to infiltrate into the ground. The road side ditch and shoulder area along 226t" St SW collect runoff from the road and then allows the runoff to infiltrate into the ground; the pipe/shoulder/shallow ditch systems along the frontage does not have a direct conveyance system that routes runoff to Deer Creek. It appears that if a significant rainfall event occurred the runoff would flow westerly (following the natural contours of the area) and then flow south down 108t" Ave W (N Deer Dr) towards Deer Creek; eventually discharge into Deer Creek about 900 ft south of the site. Deer Creek continues in a westerly direction and eventually discharges into the Puget Sound about 4,400 feet west of the site. See attached watershed and downstream drainage facility map for the local downstream path. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page F-1 F-2. Watershed Basin Map N FIGURE B - 1 CITY OF EDMONDS W we'c • "' WATERSHEDS Deer Creek Perrinvdle c I CEdmonds Marsh - Puget Sound Meadowdale A Edmonds Way If! Puget Sound Piped Meadowdale B frundale n Shell Creek ��'•re as ® Good Hope Pond Shellabarger —_ ®Halls Creek �Southwest EdmondsA 'L - Hindley Creek Southwest Edmonds B Outfall CreekStilthouse Creek , ® Lake Ballinger C Sulthouse Creek - W nd's Gulch Talbot Park A Q Meadowdale A Q Talbot Park S // L r � L•rr..i:v Gv�6 i L.. Meadowdale B Terrace Creek T Horthstream Westgate Pond OuNall Creek Willow Creek Pdrittvllle s.000 z.aao ..aoo saoo r.r. Puget Sound w 1 an 2,00Bh Talbot Park A Talbot Park B o +'a'ra'aV M arN rot cW1Y x[vrary, Rrvss, a nucN+vCiIM1 I `- ,.rd*wnrmc naaua. I S ; zoto 7. l �u�6• hstmam �- ""�' st SW L I �s 1aT_n I - - - Good Hope Pond osm It s" f Puget Sound Piped ,; r•• LPL, Edmonds Marsh -` "• Shell Creek rum n sw Shellabarger � �/ � , 3 i Westgate Pond Halls Creek SITE ------------ua�nt,W----, i- 3 s Willow Leek i I zxamusw ¢ C � F , I — j Deer Creek i �,\ sssat stsw ,i3 Edmonds Way I D—n Southwest Edmonds ALake BallingerSouthwest Edmonds B tn RAM =ngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 226th St SW Page F-2 F-3. Short Plat Downstream Drainage Facility Map (City of Edmonds GIS) RO�klftbf—A y2.3e,U-T tW- A - r �Nb S w4Y� N ALGONQUIIV RD DEER CREEK N DEER DR r reek 1:4PCSID NVS� RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 SITE i i � 6:0I a O PD12 . o PD12-: * �I o 2 6 TH SST SW� I,� I i I I ■r�i �. 26TIl I>L Sw :01 i PoI151s;1 PD .50 Cy lb15.49O 0 . o Y.._224TH Pt Sw 1 L o sR LU I»� Q O l J I. -,A 18 Johannessen Short Plat Lot 1 #10731 226t" St SW Page F-3 G. GRADING and EROSION CONTROL SUMMARY: The project will require grading to construct the proposed house and utilities (including the stormwater infiltration trench/dry well system). Standard erosion control measures are proposed to be used during construction. The primary erosion and sediment control BMP during construction will be proper soil stabilization methods. Exposed soils shall be stabilized by application of effective BMPs that protect the soil from the erosive forces of raindrops, flowing water, and wind. Applicable practices include, but not limited to, temporary and permanent seeding, sodding, mulching, plastic covering, erosion control fabrics, matting, soil application of polyacrylamide (pam), the early application of gravel base on areas to be paved, and dust control. The contractor shall select a soil stabilization method best suited for the particular situation. Stockpiles must be stabilized and protected with sediment trapping measures. In addition, site containment of exposed soils shall be sustained by using silt fence barriers along the down -slope boundaries of the site's disturbance areas. See the site development plan for details. Soils: In accordance with the project's site specific geotechnical engineering study by Earth Solutions NW, LLC the on -site soils consist of poorly graded gravel with sand and poorly graded sand (Unified Soil Classification System: GP and SP) outwash deposits. The subject site is underlain by outwash (Qva) deposits; Everett series soils. Everett soils are well drained soil and are categorized as a hydrologic group A soil. Earth Solutions NW, LLC. Recommends a long-term design infiltration rate of 18.0 inches per hour. Full soils description is included in the project's site specific geotechnical engineering study by Earth Solutions NW, LLC. Construction Stormwater Pollution Prevention Plan (SWPPP): The following is a summary of the site's erosion control measures that evaluates the typical DOE 13 elements of a SWPPP: Element 1: Mark Clearing Limits: Clearing limits have been delineated on the engineering site development plans. Element 2: Establish Construction Access: A construction access has been delineated on the engineering site development plans. Element 3: Control Flow Rates: Due to the underlying outwash soils no flow control system (ie: temporary pond) is proposed. During construction silt fencing will provide attenuation of site runoff and upon project completion and stabilization (established lawns and landscape of exposed soils), the infiltration storm system will provide flow control. Element 4: Install Sediment Controls: Filter fabric fence has been delineated and detailed on the engineering site development plans. At a minimum, silt fence will be installed along the down gradient perimeter of the disturbed area that will receive sediment -laden runoff. Element 5: Stabilize Soils: Soils will be stabilized per the TESC notes listed on the engineering site development plans. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page G-1 Element 6: Protect Slopes: Exposed slopes shall be stabilized per the TESC notes listed on the engineering site development plans. Element 7: Protect Drain Inlets: Drain inlet protection will be installed on all catch basins that will receive sediment -laden runoff. See the engineering site development plans for locations and detail. Element 8: Stabilize Channels and Outlets: This element is not applicable since there are no temporary channels or outlets proposed. Element 9: Control Pollutants: Pollutants shall be managed as described in the TESC notes listed on the engineering site development plans. Element 10: Control De -Watering: Highly turbid or contaminated de -watering water shall be handled separately from stormwater. The water from all de -watering systems for trench/dry wells and foundations shall be treated or disposed prior to discharging from the site. Element 11: Maintain BMPs: BMPs shall be maintained and removed at the end of the project as follows: i. All temporary and permanent erosion and sediment control BMPs shall be inspected, maintained and repaired in accordance with the Drainage Manual or as approved or required by the City to assure continued performance of their intended function in accordance with BMP specifications. ii. The applicant may remove temporary BMPs when they are no longer needed. iii. All temporary erosion and sediment control BMPs shall be removed within 30 days after construction is completed and the City has determined that the site is stabilized. Element 12: Manage the Project: The owner of the site is responsible for managing the installation and maintenance of the site BMPs. Element 13. Protect Low Impact Development BMPs: During construction the proposed infiltration trench/dry well systems areas shall be protected from sediment accumulation, sediment -laden runoff and soils, and compaction from construction equipment. Soils restoration and/or replacement may be needed if soils are compacted or contaminated with sediment. Conclusion: The final site development construction plans include specific grading and drainage improvement notes and details. With proper installation, maintenance and inspections of the proposed construction the project should have minimal impact to the surrounding environment. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page G-2 G-1. Soils Map (City of Edmonds) ".Figure B-2 City of Edmonds Soil Map Units (SCS 1983) LEGEND C ty of Edmonds Boundary &A Nap Unt, SOIL NAA1E Aller.o]d Gravely sandy barn. 2-8 4, slopes ak761wood GraveAy sandy loam. 8.15 % slopes ?laen•.00d Gravely sandy low. 15-25 % slo-es bens ood Lkban land ocmplex. 2.8 `a, slopes >yen•. ood Man WM complex. 8.15 % sopes �1oen.00d-Uema G,a,enj sandy, oams. 25-7C -Ver fix sandy loam j Evand graves ly saW wrn, Q8% slopes Evere. grax,ly send oam, 8.15 %slopes Everett gra,w,ly sand loam, 15.2s % sop- =:uvapuents. tidal Kasap Sla klarn, 0.8 %Slopes Kdsap sla loam. B-25 % slopes MCKO-a graxrly sin loam. 0-8 %slopes Ei Nlukraeo muds Pas llrbar, Land t :dJ 2 0M s O[O 8 000 0.000 Feet 1 In - 2.000 tt !b w,renq d mr :in. mtlusno eccuxl mesa ar nercnax ever eccompanx tr. go0,et RAM =ngineering, Inc. Engineering and Drainage Report RAM No. 17-002 #I ru yr y ,rsa —s tr ,w - a � I $Rt I - t air. mA ■ • Johannessen Short Plat Lot 1 #10731 226t" St SW Page G-3 H. OPERATION AND MAINTENANCE GUIDELINES: These guidelines are intended to provide operation and maintenance instructions for the project's storm drainage control facilities. The owner is responsible for maintenance of storm drainage facilities within the property (private property owner system); the owner is not responsible for maintenance within the public right-of-way (City system). Private Property Owners: Private property owners are responsible for properly maintaining the stormwater infrastructure on their property to ensure it operates as designed. The City has developed an inspection program to ensure private property owners are properly maintaining their stormwater systems. City System: City crews perform maintenance activities on the entire storm drainage system, including inspection and cleaning of catch basins, street sweeping, emergency flooding response, creek maintenance, inspection and monitoring of private stormwater detention systems. Operation and Maintenance Requirements for private property owner system: This manual is not comprehensive; although it explains the intended operation of the various components of the drainage system, and suggests a routine of inspection and maintenance, it cannot anticipate every problem. Once a historical record of maintenance is established, it may be prudent to alter the routine. It is recommended that maintenance records be kept, and that the records be reviewed periodically. Concept of Operation: The drainage design is shown and described in the site development engineering plans and report. The approved site development plans and report should be retained by the owner and used as a reference to identify drainage facilities outlined in this manual. Conveyance Systems. The design objective in pipe sizing was to convey the large storm events without the water surface exceeding the ground elevation. Frequent overtopping of the pipe system in a particular area might indicate a downstream blockage. Overtopping of the drain systems at the catch -basins is an indication that maintenance is required. Stormwater Infiltration Trench/Dry Well System. The private onsite infiltration trench/dry well systems consist of excavated trench/pit filled with drain rock per the City Standard detail (Handout #E72 B, Figure A-3). The infiltration trench/dry well system has been designed to infiltrate most storm event; if an extraordinary event was to occur or multiple back to back large storm events occurred the upstream catch -basins may overtop and overflow into the street system. If regular overtopping of the catch basin is experienced the system shall be thoroughly cleaned and inspected. Over a period of time siltation of the infiltration bed can occur (especially if the system and upstream catch basin are not inspected and cleaned regularly) and replacement of the rock in the infiltration system may be required. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page H-1 The following pages outline standard general maintenance criteria for the project's drainage facilities. For additional and updated maintenance information visit the Washington State Department of Ecology's web -site at: http://www.ecy.wa.gov/programs/wq/wghome.htmI MAINTENANCE REQUIREMENTS ECDC Section 18.30.090 requires privately -owned stormwater management facilities, such as LID BMPs be properly maintained. The owner of the property is the responsible party for such maintenance. The system must be kept in good working order. The entire system should be inspected once per year. An improperly maintained BMP may cause private property or street flooding. Contact the City Engineering Division for maintenance information. The City may make periodic inspections of BMPs to ensure they are operating properly. ECDC Section 18.30.100 contains the enforcement provisions the City can use to ensure the system is properly maintained. General Infiltration Maintenance Criteria Provision should be made for regular and perpetual maintenance of the infiltration basin/trench, including replacement and/or reconstruction of the any media that are relied upon for treatment purposes. Maintenance should be conducted when water remains in the basin or trench for more than 24 hours after the end of a rainfall event, or when overflows occur more frequently than planned. For example, off-line infiltration facilities should not have any overflows. Infiltration facilities designed to completely infiltrate all flows to meet flow control standards should not overflow. Removal of accumulated debris/sediment in the basin/trench should be conducted every 6 months or as needed to prevent clogging, or when water remains in the pond for greater than 24 hours after the end of a rainfall event. RAM -ngineering, Ine Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page H-2 Appendix V-A: BMP Maintenance Tables Ecology intends the facility -specific maintenance standards contained in this section to be conditions for determining if maintenance actions are required as identified through inspection. Recognizing that Permittees have limited maintenance funds and time, Ecology does not require that a Permittee perform all these maintenance activities on all their stormwater BMPs. We leave the determination of importance of each maintenance activity and its priority within the stormwater program to the Permittee. We do expect, however, that sufficient maintenance will occur to ensure that the BMPs continue to operate as designed to protect ground and surface waters. Ecology doesn't intend that these measures identify the facility's required condition at all times between inspections. In other words, exceedance of these conditions at any time between inspections and/or maintenance does not automatically constitute a violation of these standards. However, based upon inspection observations, the Permittee shall adjust inspection and maintenance schedules to minimize the length of time that a facility is in a condition that requires a maintenance action. Table V-A.1: Maintenance Standards - Detention Ponds Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed Any trash and debris which exceed 1 cubic feet per 1,000 square feet. In general, there should be no visual evidence of Trash &Debris dumping. Trash and debris cleared from site If less than threshold all trash and debris will be removed as part of next scheduled maintenance. Any poisonous or nuisance vegetation which may constitute No danger of poisonous General a hazard to maintenance vegetation where maintenance personnel or the public. personnel or the public might normally be. (Coordinate with Poisonous Any evidence of noxious weeds local health department) Vegetation and as defined by State or local noxious weeds regulations. Complete eradication of noxious weeds may not be possible. (Apply requirements of adopted Compliance with State or local IPM policies for the use of eradication policies required herbicides). Contaminants and Any evidence of oil, gasoline, No contaminants or pollutants Pollution contaminants or other pollutants present. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261h St SW Page H-3 Table V-A.1: Maintenance Standards - Detention Ponds Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed (Coordinate removal/cleanup with local water quality response agency). Any evidence of rodent holes if Rodents destroyed and dam or facility is acting as a dam or berm repaired. (Coordinate with Rodent Holes berm, or any evidence of water local health department; piping through dam or berm via coordinate with Ecology Dam rodent holes. Safety Office if pond exceeds 10 acre-feet.) Facility is returned to design function. Beaver Dams Dam results in change or function of the facility. (Coordinate trapping of beavers and removal of dams with appropriate permitting agencies) Insects destroyed or removed When insects such as wasps from site. Insects and hornets interfere with maintenance activities. Apply insecticides in compliance with adopted IPM policies Tree growth does not allow maintenance and inspection access or interferes with maintenance activity (i.e., slope mowing, silt removal, vactoring, Trees do not hinder or equipment movements). If maintenance activities. trees are not interfering with Harvested trees should be Tree Growth and access or maintenance, do not recycled into mulch or other Hazard Trees remove beneficial uses (e.g., alders for firewood). If dead, diseased, or dying trees are identified Remove hazard Trees (Use a certified Arborist to determine health of tree or removal requirements) Side Slopes of Pond Erosion Eroded damage over 2 inches Slopes should be stabilized deep where cause of damage is using appropriate erosion control measures ; e. .,rock RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261h St SW Page H-4 Table V-A.1: Maintenance Standards - Detention Ponds Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed still present or where there is reinforcement, planting of grass, potential for continued erosion. compaction. Any erosion observed on a If erosion is occurring on compacted berm embankment. compacted berms a licensed engineer in the state of Washington should be consulted to resolve source of erosion. Accumulated sediment that exceeds 10% of the designed Sediment cleaned out to Sediment pond depth unless otherwise designed pond shape and specified or affects inletting or depth; pond reseeded if Storage Area outletting condition of the necessary to control erosion. facility. Liner (if Applicable) Liner is visible and has more Liner repaired or replaced. Liner than three 1/4-inch holes in it. is fully covered. Any part of berm which has settled 4 inches lower than the design elevation If settlement is apparent, measure berm to determine amount of settlement Dike is built back to the design Settlements elevation. Settling can be an indication of more severe problems with the berm or outlet works. A licensed Ponds Berms engineer in the state of (Dikes) Washington should be consulted to determine the source of the settlement. Discernable water flow through pond berm. Ongoing erosion with potential for erosion to continue. Piping Piping eliminated. Erosion potential resolved. (Recommend a Goethechnical engineer be called in to inspect and evaluate condition and recommend repair of condition. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261h St SW Page H-5 Table V-A.1: Maintenance Standards - Detention Ponds Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed Tree growth on emergency Trees should be removed. If root spillways creates blockage system is small (base less than problems and may cause failure 4 inches) the root system may of the berm due to uncontrolled be left in place. Otherwise the Tree Growth overtopping. roots should be removed and the berm restored. A licensed Tree growth on berms over 4 engineer in the state of feet in height may lead to piping Washington should be consulted Emergency through the berm which could for proper berm/spillway Overflow/ Spillway lead to failure of the berm. restoration. and Berms over 4 feet in height Discernable water flow through pond berm. Ongoing erosion with potential for erosion to continue. Piping Piping eliminated. Erosion potential resolved. (Recommend a Geotechnical engineer be called in to inspect and evaluate condition and recommend repair of condition. Only one layer of rock exists above native soil in area five square feet or larger, or any Emergency Emergency exposure of native soil at the Rocks and pad depth are Overflow/Spillway Overflow/Spillway top of out flow path of spillway. restored to design standards. (Rip -rap on inside slopes need not be replaced.) Erosion See "Side Slopes of Pond" Table V-A.2: Maintenance Standards - Infiltration Maintenance Defect Conditions When Maintenance Is Component I I Needed General Trash & Debris See Table V-A.1: Maintenance Standards - Detention Ponds RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Results Expected When Maintenance Is Performed See Table V-A.1: Maintenance Standards - Detention Ponds Johannessen Short Plat Lot 1 #10731 2261h St SW Page H-6 Table V-A.2: Maintenance Standards - Infiltration Maintenance Conditions When Maintenance Is Results Expected Component Defect Needed When Maintenance Is Performed See Table V-A.1: Poisonous/Noxious See Table V-A.1: Maintenance Maintenance Vegetation Standards - Detention Ponds Standards - Detention Ponds See Table V-A.1: Contaminants and See Table V-A.1: Maintenance Maintenance Pollution Standards - Detention Ponds Standards - Detention Ponds See Table V-A.1: Rodent Holes See Table V-A.1: Maintenance Maintenance Standards - Detention Ponds Standards - Detention Ponds Water ponding in infiltration pond after rainfall ceases and appropriate time allowed for infiltration. Treatment basins should infiltrate Water Quality Design Storm Volume within 48 hours, and Sediment is removed empty within 24 hours after cessation of and/or facility is Storage Area Sediment most rain events. cleaned so that infiltration system works according to (A percolation test pit or test of facility design. indicates facility is only working at 90% of its designed capabilities. Test every 2 to 5 years. If two inches or more sediment is present, remove). Filter Bags (if Filled with Sediment Sediment and debris fill bag more than Filter bag is replaced applicable) and Debris 1/2 full. or system is redesigned. By visual inspection, little or no water Gravel in rock filter is Rock Filters Sediment and Debris flows through filter during heavy rain replaced. storms. See Table V-A.1: Side Slopes of Erosion See Table V-A.1: Maintenance Maintenance Pond Standards - Detention Ponds Standards - Detention Ponds Emergency Tree Growth See Table V-A.1: Maintenance See Table V-A.1: Overflow Spillway Standards - Detention Ponds Maintenance RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261h St SW Page H-7 Table V-A.2: Maintenance Standards - Infiltration Maintenance Conditions When Maintenance Is Results Expected Component Defect Needed When Maintenance Is Performed and Berms over 4 Standards - Detention Ponds feet in height. See Table V-A.1: Piping See Table V-A.1: Maintenance Maintenance Standards - Detention Ponds Standards - Detention Ponds See Table V-A.1: Rock Missing See Table V-A.1: Maintenance Maintenance Standards - Detention Ponds Standards - Detention Ponds Emergency Overflow Spillway See Table V-A.1: Erosion See Table V-A.1: Maintenance Maintenance Standards - Detention Ponds Standards - Detention Ponds Pre -settling Ponds Facility or sump filled 6" or designed sediment trap depth of and Vaults with Sediment and/or sediment. Sediment is removed. debris Table V-A.S: Maintenance Standards - Catch Basins Maintenance Component Defect Conditions When Maintenance is Needed Results Expected When Maintenance is performed Trash or debris which is located immediately in No Trash or debris front of the catch basin opening or is blocking located immediately in inletting capacity of the basin by more than front of catch basin or 10%. on grate opening. General Trash & Debris Trash or debris in the basin that exceeds 60 ( ) No trash or debris in percent of the sump depth as measured from the 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 Inlet and outlet pipes debris surface to the invert of the lowest pipe. free of trash or debris. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261h St SW Page H-8 Table V-A.5: Maintenance Standards - Catch Basins Maintenance Results Expected Component Defect Conditions When Maintenance is Needed When Maintenance is performed Trash or debris in any inlet or outlet pipe No dead animals or blocking more than 1/3 of its height. vegetation present within the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). Sediment (in the basin) that exceeds 60 percent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than No sediment in the Sediment a minimum of 6 inches clearance from the catch basin sediment surface to the invert of the lowest pipe. Top slab has holes larger than 2 square inches Top slab is free of or cracks wider than 1/4 inch. (Intent is to make holes and cracks. Structure Damage sure no material is running into basin). to Frame and/or Frame is sitting flush Top Slab Frame not sitting flush on top slab, i.e., on the riser rings or top separation of more than 3/4 inch of the frame slab and firmly from the top slab. Frame not securely attached attached. Maintenance person judges that structure is Basin replaced or unsound. repaired to design Fractures or standards. Cracks in Basin Grout fillet has separated or cracked wider than Walls/ Bottom 1 /2 inch and longer than 1 foot at the joint of Pipe is and any inlet/outlet pipe or any evidence of soil t basinn wall. secure at basin a particles entering catch basin through cracks. Settlement/ If failure of basin has created a safety, function, Basin replaced or repaired design Misalignment or design problem. standards. No vegetation blocking opening to basin. Vegetation Vegetation growing across and blocking more than 10 /o of the basin opening. No vegetation or root growth present. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261h St SW Page H-9 Table V-A.S: Maintenance Standards - Catch Basins Maintenance Results Expected Component Defect Conditions When Maintenance is Needed When Maintenance is performed Vegetation growing in inlet/outlet pipe joints that is more than six inches tall and less than six inches apart. Contamination See Table V-A.1: Maintenance Standards - No pollution present. Detention Ponds and Pollution Cover/grate is in place, Cover Not in Cover is missing or only partially in place. Any meets design Place open catch basin requires maintenance. standards, and is secured Locking Mechanism cannot be opened by one Mechanism opens with Catch Basin Mechanism Not maintenance person with proper tools. Bolts proper tools. Cover Working into frame have less than 1/2 inch of thread. One maintenance person cannot remove lid after applying normal lifting pressure. Cover can be removed Cover Difficult to by one maintenance Remove (Intent is keep cover from sealing off access to person. maintenance.) Ladder is unsafe due to missing rungs, not Ladder meets design Ladder Ladder Rungs securely attached to basin wall, misalignment, standards and allows Unsafe rust, cracks, or sharp edges. maintenance person safe access. Grate opening Grate with opening wider than 7/8 inch. Grate opening meets Unsafe design standards. Trash and Debris Trash and debris that is blocking more than Grate free of trash and Metal Grates 20% of grate surface inletting capacity. debris. (If Applicable) Grate is in place, meets Damaged or Grate missing or broken member(s) of the the design standards, Missing. grate. and is installed and aligned with the flow path. RAMEngineering, Inc. Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261h St SW Page H-10 I. GEOTECHNICAL ENGINEERING REPORT Geotechnical Engineering Study. Prepared by: Earth Solutions NW, LLC Date: July 19, 2017 RAM ninaarinn Ir Engineering and Drainage Report RAM No. 17-002 Johannessen Short Plat Lot 1 #10731 2261" St SW Page 1-1 Flj%I ENGINEERING, INC. Civil Engineering / Land Planning