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HomeMy WebLinkAboutPermit File BLD-2021-0730 3206 R Avenue (4) t 'Ri s 'WV c� 4 ; Storm Water Drainage Repart • . . t ;041 1 f: v inimum Requirements 1 through 9 275307 ENGINEERING DEPARTMENT a i�vl �"`s's•UN 1 ZU._2.�Z 1 904 e'h Street ant oI-tesw ortes, WA 8221 , www Official Use Only: (Information to Inspectors) Required Storm Water Facility and other related requirements: T 5•tor✓—+r�a2 w st3c7 Pt�c nl�zTlaJ h 13mP - to �lv►J r'� , . > �►Lt—> �.t.a,�ri1 ctJ KtT^ nek it"Z- 2r1. T.=1 x __��^-L��►�rt�Jc "ti^�ss1�s Fbe� -sue^ rc 9 S - Lo..a - Project Address_-3:2"° & R.Avenue Submittal Date: D'7- - ZGZ Parcel Number: Peosee Revision Number: LS - PermitNumber: _BLD-2021- Reviewer: ^- ; oS¢-„e^ • AcceptanceiDate(CON: er6.o'b,-Z.io.2-t FRONT.OF REPORT: Submittal Checklist: (All items listed below are required for a complete submittal) o Cover Sheet (Preparer to Provide): Project title, Location,-Revision dates, Engineer's Stamp o TAB 1: Minimum Requirement#1 -Preparation of Stormwater Site Plans c, TAB 2: Minimum Requirement#2 -Construction Stormwater Pollution Prevention (8WPP) o TAB 3: Minimum'Requirement #3 -'Source Control of Pollution o TAB 4: Minimum'Requirement#4 -Preservation of Natural Drainage Systems and Duffel's o TAB 5: Minimum:Requirement #5 -On-site Stormwater Managements o TAB 6: Minimum Requirement,#6 -Runoff. Treatment o TAB 7: Minimum Requirement#7 -Flow Control o TAB 8: Minimum Requirement #8 -VVetland Protection o TAB 9: Nlinimurn Requirement#9 -Operation and Maintenance a APPENDIX 1 - Survey performed by a Professional Land Surveyor a APPENDIX 2- Soils.Analysis (Volume 1., Chapter 3.1.1,) o APPENDIX 3- Model Soil .Management Plan for BMP T5.13 -o APPENDIX 4- Determining Construction Site Sediment Damage:,Potential (Appendix 7) o APPENDIX 5- Site Plan with all applicable"information (Minimum :Size 1 1 x17-30 scale) o APPENDIX .6- Documented Site Photos (.North,South, East and West) o APPENDIX 7- Drainage BMP Facility Maintenance .Covenant, if applicable. To be recorded prior to the Temporary Certificate of Occupancy, Certificate of Occupancy or Final Acceptance. FLOW CONTROL EXEMPT Stormwater Management Requirements: 'Version Date• October 7, 2019 Previous Version Date. February .20, 2019 o Refer to the 2012\14 Department of Ecology Manual, as amended in 2014 for further required information. o See also, City of Anacortes Municipal Code 19.76 for additional information o See also, current Engineering Development Standards, Chapter 2- Storm Drainage for additional information. Project Description and Summary: Summary Table Existing Proposed Development Type Undeveloped Multifamily Number of Lots 1 Lot Acreage in SF 14,999 SF Soil Type(s) Bow Urban Land Complex HG C/D Site Sediment Transport Score (High\Low) Low 95 Low 95 Depth to Ground Water Table (Feet and Inches) Under 20" (See completed Soils Analysis(Volume 1, Chapter 3.1.1) Infiltration Rate during Rainy Season (Inch\Per Hour) N/A Impervious Surface (on-site) O 10,644 sf Impervious Surface (off-site) O O New and Replaced Hard Surface Total (SF) O 10,644 sf Lot Coverage (Percentage) _O 70% _ BMP (Required Minimum Requirement 5) BMP T5.13 Post Construction Soils BMP T7.30 Bioretention Cell Water Quality Method (Minimum Requirement 6) N/A Water Quantity Method (Minimum Requirement 7) N/A Existing Site Conditions Summary: (Additionally, provide information on previous permits, if any, like Grade and Fill, Clear and Grade, topography, vegetation, drainage, Critical Areas adjacent to the site and how it may affect this project if soils are disturbed, Soils Type (Included in Soils Analysis Report), Erosion Problem Areas, Construction Phasing\Sequence) The 14,999 square foot lot is undeveloped grass. The existing home, shops and gravel parking areas have been removed. The site slopes from the back southwest corner of the site to the northeast corner of the site at approximately 4.5%. A single family home lies to the west. The north (32nd Street) and east(R Avenue) frontage has an existing sidewalk with curb and gutter. An existing storm systems lies along the north 32^d Street frontage. The closest catch basin is just north of the northeast corner of the site. A gravel alley lies along the south boundary. Developed Conditions Summary: (Additionally, to be shown on the site plan. Identify cut and fill areas,. proposed slopes of all hard surfaces , proposed contours) The proposal is to construct two 5 unit multifamily townhomes totaling 7,786 square foot building area. Also a 732 square foot sidewalk and 2,126 square foot paved driveway. Cuts and fills will be minimal. Roof drainage will be directed to the existing storm system in the northeast corner of the site. Drainage Basin (2007 Storm Comp Plan—City website\publicworks\engineering\comprehensive plans): What Drainage Basin are you in? F4 Identify any downstream drainage issues (Storm Comp Plan: Yes. If so, describe: An existing catch basin is located in the curb line on the south side of 32ntl Avenue at the Version Date: October 7, 2019 Previous Version Date: February 20, 2019 northeast corner of the site. The storm drainage system from here to Fidalgo Bay is an enclosed storm pipe to the Bay approximately 2,676 feet. The first '/. mile of storm system has surcharged issues in the 2007 storm comp plan. The city completed additional flow volume study and came to the conclusion that the down stream system has capacity for the typical storm event in Anacortes. Complete the Applicability Requirements -Flow Chart (Figure 1-2.4.1 Attached, Figure 1-2.4.2 Attached and Figure 1-2.5.1 Attached) Version Date: October 7, 2019 Previous Version Date: February 20, 2019 Figure 1-2.4_1 Flow Chart for Determiniing Reguirements for New Development Start Here 1 Goes the site have.35% Yes See RedevelOpment'Minirrlunt or more of existing - ►. Requirements and'Flow-Ohart impervious coverage? (Figure 1=2,4.2). Na Ones the project convert X .acres or-more of vegetation to Does the project result in lawn•or landscaped areas,or 5,C100 square feet.or Noconvert 2:5-acieser more of greater,of new plus - It, native vegetation to pasture? replaced hard surface • area? -- No Yes Yea Does•the project result in 2,000 square feet,or•greater,of new-plus. All Minimum Requirements replaced hard surface area? apply to-the new-and replaced nerd surfaces and converted Yes NO 'vegetation areas. r Does the project have land Minimum Requirements#.1 disturbing activities of 7,000 throug #5.apply to the--new 11 square feet-or greater? and replaced hard.surfaces Y@S and the land disturbed. .N iD Minimum Requhement # applies. Figure I n tl Flow Cart for Determining Requirements for New Developme-nt DEPARTMENT OF Revieed June201S E COL O G-Y pleasesee-htfp:h'waw.oey wa gov]copyrfghl.htin/for copyright notice including permlecions. State Of Washington limitation of liability,and disclaimer. 2014 Stormwater Management Manua/for-Western Washington Volume I-Chapter 2-Page 37 Version Date_ October 7, 2019 Previous Version Date: February 20, 2019 TAB 1 (MINIMUM REQUIREMENT#1) 1-2.5.1 Minimum Requirement#1 — Prepare a Stormwater Site Plan 1.3 — Preparation of a Stormwater Site Plan - 1.3.1 —Stormwater Site Plans: Step-by-Step Note: The level of detail needed for each step depends upon the project size. Provide a narrative description of each step. 1-3.1_1 Step 1 - Site Analysis: Collect and Analyze Information on Existing Conditions Site analysis shall be submitted as part of the Existing Conditions Summary above. Part of the information in this step should be used to help prepare the Construction Stormwater Pollution Prevention Plan. Purpose of the Site Analysis is to provide for a Low Impact Development site design that is intended to compliment the predeveloped conditions of the site. A stormwater site plan has been prepared showing erosion control methods for this site_ The site slopes at 4.5% to the northeast corner of the site. The uphill property is developed with single family homes_ The soils report was completed for the property just to the south of this site and is included in Appendix 2 identifies the soils as Bow Urban Land Complex Hydrologic group CM with a anticipated water table from 16" to 20" in depth. The soils do not allow for infiltration. 1-3.1.2 Step 2 - Prepare Preliminary Development Layout Based upon the analysis of existing site conditions, locate the buildings, roads, parking lots, landscaping features, on-site stormwater management BMP's, and preliminary location of stormwater treatment and retention/detention facilities for the proposed development. BMP's will include covering soil stock piles and protecting down slope properties with silt fencing. The proposed paved driveway will act as the construction entrance with gravel until paved (BMP C107). Grading will only be in the area of the house foundation and exposed to erosion until the foundation is complete and backfilled. Version Date: October 7, 2019 Previous Version Date: February 20, 2019 1-3.1.3 Step 3- Perform Off-site Analysis (at Local Agency's Option): Use additional Sheets, if necessary, Ecology recommends that local governments require an off-site analysis for projects that add 5,000 SF or more of new hard surfaces, or convert'/. acres of vegetation to lawn or landscape areas, or convert 2.5 acres of forested area to pasture. Off-site analysis extends to 'A mile downstream of the project site. Two catch basins are located in the curb line at the northeast corner of the site at 32^" Street and "R" Avenue. The storm drainage system from here to Fidalgo Bay is an enclosed storm pipe for a distance of 2,676 feet. 1-3.1.4 - Determine Applicable Minimum Requirements Establish project size thresholds for the application of Minimum Requirements to new development and redevelopment projects. Figures 2.4.1 (Attached) and 2.4.2 (Attached) provide the same thresholds in a flow chart format. Based on the preliminary layout, determine whether Minimum Requirements#1 through *5 apply to the project; or, whether Minimum Requirements#1 through*9 apply. Please note, that Minimum Requirement*1 through*5 may trigger additional Minimum Requirements, such as Flow Control. The total new impervious area added to this site will be 10,644 square feet and over the 5,000 square foot threshold and triggers minimum requirements 1 through 9. 1-3.1.5 Step 5- Prepare a Permanent Stormwater Control Plan (Refer to this section of the Ecology Manual for requirements.) A storm water plan is provided in the developed site plan in Appendix 5. The drainage system will be described in minimum requirement#5 below. 1-3.1_6 Step 6 - Prepare a Construction Stormwater Pollution Prevention Plan (MR*2— 13 .Elements) Refer to Chapter 11-3— Planning for a detailed description of each element. See also attached Tables 4.1.1 (Source Control BMP's by SWPPP Element) and Table 4.2.1 ()Runoff Conveyance and Treatment BMP's by SWPPP Element). See attached 13 Elements of a SWPPP, please complete and attached 1-3.1.7 Step 7 - Complete the stormwater site plan The Stormwater Site Plan encompasses the entire submittal to the Local Agency with drainage review authority. Refer to this section of the Manual for further clarification of each item and what is required. See below: • Project Overview Version Date: October 7, 2019 Previous Version Date: February 20, 2019 • Existing Conditions Summary . Off-site Analysis Report • Permanent Stormwater Control Plan • Construction Stormwater Pollution Prevention Plan • Special Reports and Studies • Other Permits . Operation and Maintenance Manual . Declaration of Covenant for Privately Maintained Flow Control and Treatment Facilities. I (Sae attached Drainage BMP Maintenance Covenant BMP Agreement) • Declaration of Covenant for Privately Maintained On-site Stormwater BMP's (See attached Drainage BMP Maintenance Covenant BMP Agreement) . Bond Quantities Worksheet, if applicable The project overview has been provided at the beginning of this report along with an existing conditions description. Maps are included in the attachments. 1-3.1_8 Step 8 -Check Compliance with all Applicable Minimum Requirements • A Stormwater Site Plan as designed and implemented should specifically fulfill all Minimum Requirements applicable to the project. The Stormwater Site Plan should be reviewed to check that these requirements are satisfied. To take place during review and during and after construction. • Version Date: October 7, 2019 Previous Version Date: February 20, 2019 TAB 2 (MINIMUM REQUIREMENT#2) 1-2.5.2 Minimum Requirement#2— Construction Stormwater Pollution Prevention Plan (SWPP) - All projects are required to complete Minimum Requirement 2. - Refer to the 13 Elements of the SWPP (See document below, complete and attach) - See attached Table 4.1.1, Table 4.2.1 and Table - Provide Engineering Calculations as an attachment for Sediment Ponds\Traps, Diversions, Waterways and Runoff/Stormwater Detention Calculations. Table 4.1.1 Source Control BMP's by SWPPP Element Version Date: October 7, 2019 Previous Version Date: February 20, 2019 Element el Element SO Element 113 Eenr Element H e05 Enront l6 Elament OS ElementaHl Els tre2 BOP or Elomont Naar PrEstablishorveEstablishProtect Low h Stahfteo PPo O O tfel Control nlntnin anege tha Vogonrbn/Mark Conalmarbn Soda Slopes Pollutants BMPs Prcdeet Impact Clamant,I lets Access Oerolonrn= aMP C101:Preset..lrrg Natured Vegetation ✓ BMP C102:Buffo,Zorroa ✓ ✓ MAP C103:High Ns1610q.Mantle or Mat ✓ Fence BMP C105: Stababwd Construction ✓ Entrance f Esti BMP CMG:Wheel Mesh ✓ BMP C1OT:Conntructtun RaadlPatkrp Iron Saahalaaaon BMP C120:Temporary and Permmant ✓ ✓ lauding BMP C121: Mulching ✓ ✓ BOP C122: Nab and Bkarkob ✓ ✓ BMP C125: PlaaNe Ce arring ✓ IMP C124c Sodding ✓ BMP C125:Topaolling/Composting ✓ BUS C128: Potyeeryleinide tor foil Erosion Prorosotion SNAP C120: Sadao.Roughnning ✓ ✓ BMP C131:GrstNmt Ternns ✓ tr' BMP C140: DuatControl ®MP C100: Madarbb On Hand ✓ .f BMP C151:Conerota Handling ✓ BMP C182: SaseuHing and Sueaelru ✓ Pofulan Procaine/on BMP C103: Malarial Salaam Starago and N, Conbanrrnt BMP C134:COsrareto YUeahoue Mao ✓ BMP C100:CartWad Erosion and Sorlannnt Control Wood '". ✓ BLIP C162:Scheduling ./ Table 4.2.1 Runoff Conveyance and Treatment BMP's by SWPPP Element Version Date: October 7, 2019 Previous Version Date: February 20, 2019 _ .r M:on,cntrit14 r3Krrrartt nf6 Sloaler/t 673 Eietnoart at.. Eloon410 ME.f'eleowrErR NP Eisane rtilia ali more Pi* itsalall Sialalliz t Protest Low ca lnit r 0l4rnorrst Nast* ._ Gpn0.rol Protoi:t PFntse2 Control Ccrrbrol no. . • S4.dirnemt ti7lrennralaa tryP ect Flrnrl{M1a�io¢ Slalics [)cnSeA Aiypvrx WrYuM1',rsnlz Vfa Lt.rltri7 ...�.....�. f-swFtrr�Ilo' -0nd mprrlo4s 3`ewIe7rr.Rmwnt Y-SKfP>3TJ<o41: OrRevnc-.aiPnar 091pe mr+r!K'vmie ✓ +/ 69NP C2O7:: amen-Lau rari C6 na:tat d- - - _ --- _ EIWI•C2122:Onelnton Lirdag0 IF' BILIP C203:Wailer Biers- —._....0- ✓ SA1/0402041: rNpB-alai►a.Dwain* ✓ ,- _ _ t. atY1P Cave: srrhwrfoot.bcahse - _ ., LIMP C209: Char_44'0asr* .✓ rr 4 RAMP cam:TdosrprslnriVYlt bilks[iiistifts7lAx 1 - ✓ , - ••• E almeod C6ta.nk-rso ngl aMP C209: Casillot Prerection u . . .. v.F. . . BMP C220: Snort laraln lole4 Preitadlnrt- ✓ yp# BMP G83�f. ura nrfi Bar.•sier IFS • __3 ✓ F , ,BMP cams., Strarnl l Rater El eta - rr`_ r c �.... . (SNIP C233.- Sift Faris -,,, ✓ • ®MP C2]4:144.4lwlOnati Sirlp _ ✓ - ✓ ' BMP C225::1Mattlns ' ✓ - - , BMP C2310 Vesdbatiss FNbsrEion ✓ _ BMP C2/0c 6pdir[ronE 1'mos -+!/ ✓ BM C.2P 10.Tbrripoirary IS.alerneita Fhrerd ._f ✓ , , BMP C2610 Casre6lruciiran Slionrsrsra lair 1 .. .. V, C4es'rittn TaoaAsrsut - 'y — BM ion P CZPIt Ca4atsrinn TliL4rrYNNkBr { . Pintail** ' 0MP C2100 Hilts t44 NenrIstfirtwan Ultimp Geii 4,. _. BMP CZ53...Pnn Cpntiroil for Wain pH Vardar -ir Version Date: October 7, 2019 Previous Version Date: February 20, 2019 13 Elements of SWPPP (Construction Stormwater Pollution Prevention Plan) Please check off boxes to show that each element has been read and understood. Provide details where applicable and if certain aspects are unnecessary or exempt, clearly justify. Details of the 13 Elements and the correlating BMPs are listed Above from the 2014 Stormwater Management Manual for Western Washington (SWMMWSN). A link is provided on the City of Anacortes website, under Planning, Community, & Economic Development Department, as well as under Stormwater on the Engineering Division of Public Work's page. Owner (Jame: R32 LLC Site Address:_ 3204 R Avenue Prepared By: Dale Herrigstad PE The Stormwater checklist or building permit determined that: ❑ The 13 elements must be addressed ❑ These elements must be addressed for construction activity adding under for construction activity adding 2,000 2,000 sq. ft. of hard surface area. sq. ft. or more of hard surface area. This means that an attached narrative and site plan are required with this document. Under each element. provide the BMP's that will be applicable to Your project_ Use the attached Tables provided_ ELEMENT 1: Preserve Vegetation/Mark Clearing Limits ❑ Before beginning land disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area. I� Retain the duff layer, native top soil, and natural vegetation in an undisturbed state to the maximum degree practical. A high visibility and/or a cyclone construction fence BMP C103 will be installed at the perimeter of the construction site. BMP will be installed as first step of construction. BMP C233, Silt Fence will also be used to mark the north and east down slope perimeter of the construction site including the access road. BMP to be monitored daily and repaired as needed. ELEMENT 2: Establish Construction Access LI Limit construction vehicle access and exit to one route, if possible. ❑ Stabilize access points with a pad of quarry spells, crushed rock, or other equivalent BMPs, to minimize tracking onto roads. ❑ Locate wheel wash or tire baths on site, if the stabilized construction entrance is not effective in preventing tracking sediment onto roads. 0 If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day, or more frequently as necessary (ex: wet weather). Remove sediment from roads by shoveling, sweeping, or pick up and transport the sediment to a controlled sediment disposal area. ❑ Conduct street washing only after sediment is removed in accordance with the above bullet. ❑ Control street wash wastewater by pumping back on site or otherwise preventing it from discharging into systems tributary to waters of the State. The construction entrance will be limited to one location from the alley on the south side of the project with BMP C107 (Construction Entrance.) Version Date: October 7, 2019 Previous Version Date: February 20, 2019 Any dirt or mud that is tracked onto the roadway will be clean immediately. To be installed prior to construction. BMP to be monitored daily and repaired as needed. ELEMENT 3: Control Flow Rates ❑ Protect properties and waterways downstream of development sites from erosion and the associated discharge of turbid waters due to increases in the velocity and peak volumetric flow rate of stormwater runoff from the project site. ❑ Where necessary to comply with the bullet above, construct stormwater retention or detention facilities as one of the first steps in grading. Assure that detention facilities function properly before constructing site improvement (e.g. impervious surfaces). ❑ If permanent infiltration ponds are used for flow control during construction, protect these facilities from siltation during the construction phase. A silt fence BMP C233 is to be installed on the north and east boundary along 32nd Street and along R Avenue. The majority of the site will be disturbed. A temporary sediment trap will be located in the northeast corner of the site. ELEMENT 4: Install Sediment Controls ❑ Design, install, and maintain effective erosion controls and sediment controls to minimize the discharge of pollutants. ❑ Construct sediment control BMPs (sediment ponds,traps, filters, etc.) as one of the first steps in grading. These BMPs shall be functional before other land disturbing activities take place. ❑ Minimize sediment discharges from the site. The design, installation and maintenance of erosion and sediment controls must address factors such as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soil particle sizes expected to be present on the site. ❑ Direct stormwater runoff from disturbed areas through a sediment pond or other appropriate sediment removal BMP, before the runoff leaves a construction site or before discharge to an infiltration facility. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but must meet the flow control performance standard in Element#3, bullet#1_ ❑ Locate BMPs intended to trap sediment on-site in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages. ❑ Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to increase sediment removal, and maximize stormwater infiltration. ❑ Where feasible, design outlet structures that withdraw impounded stormwater from the surface to avoid discharging sediment that is still suspended lower in the water column. Per BMP C233 a silt fence will be installed as noted in element 3. To be installed prior to the start of construction. BMP to be monitored daily and repaired as needed. BMP C162 Scheduling. ELEMENT 5: Stabilize Soils ❑ Stabilize exposed and unworked soils by application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding, mulching, plastic covering, erosion control fabrics and matting, soil application of polyacrylamide (PAM), the early application of gravel base early on areas to be paved, and dust control. ❑ Control stormwater volume and velocity within the site to minimize soil erosion. ❑ Control stormwater discharges, including both peak flow rates and total stormwater volume, to minimize erosion at outlets and to minimize downstream channel and stream bank erosion. ❑ Soils must not remain exposed and unworked for more than the time periods set forth below to prevent erosion. o During the dry season (May 1 —Sept 30): 7 days Version Date: October 7, 2019 Previous Version Date: February 20, 2019 o During the wet season (Oct 1 —Apr 30j: 2 days O Stabilize soils at the end of the shift before a holiday or weekend if needed based on the weather forecast. ❑ Stabilize soil stockpiles from erosion, protect with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. ❑ Minimize the amount of soil exposed during construction activity. ❑ Minimize the disturbance of steep slopes. ❑ Minimize soil compaction and, unless infeasible, preserve topsoil. Stabilize exposed and unworked soils b p y application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding, mulching and plastic covering. Install plastic covering per BMP C123 on Soils Stockpiles. BMP to be monitored r daily and repaired as needed. Refer to Table 4.1.1 in MR >f2. ELEMENT 6: Protect Slopes Design and construct cut-and-fill slopes in a manner to minimize erosion. Applicable practices include, but are not limited to, reducing continuous length of slope with terracing and diversions, reducing slope steepness, and roughening slope surfaces (Ex: track walking). ❑ Divert off-site stormwater(run-on) or ground water away from slopes and disturbed areas with interceptor dikes, pipes, and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site. ❑ At the top of slopes, collect drainage in pipe slop drains or protected channels to prevent erosion. o "Temporary pipe slope drains must handle the peak volumetric flow rate calculated using a 10- minute time step from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate predicted/indicated by an approved continuous runoff model, increased by a factor of 1_6, may be used. The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site,the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model (WWHM) to predict flows, bare soil areas should be modeled as "landscaped" area. o Where 15-minute time steps are available in an approved continuous runoff model, they may be used directly without a correction factor. ❑ Place excavated material on the uphill side of trenches, consistent with safety and space considerations. ❑ Place check dams at regular intervals within constructed channels that are cut down a slope. ❑ Consider soil types and its potential for erosion. ❑ Stabilize soils on slopes, as specified in Element 5. ❑ BMP combinations are the most effective method of protecting slopes with disturbed soils. Ex: Use both mulching and straw erosion control blankets. The site is flat with a 4.59/o slope and slope protection will not be an issue. ELEMENT 7: Protect Drain Inlets ❑ Protect all storm drain inlets made operable during construction so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. ❑ Clean or remove and replace inlet protection devices when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer). ❑ Where possible, protect all existing storm drain inlets so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. O Keep all approach roads clean. Do not allow sediment and street wash water to enter storm drains Version Date: October 7, 2019 Previous Version Date: February 20, 2019 without prior and adequate treatment unless treatment is provided before the storm drain discharges to II waters of the State. O Inlets should be inspected weekly at a minimum and daily during storm events. Per detail 1-40.20-00 Storm Drain Inlet protection devices will be installed at existing catch basins in the immediate vicinity of the project. To be installed prior to the start of any construction. Two catch basins are located at the northeast corner of the site along with new catch basins propose at the alley. ELEMENT 8: Stabilize Channels and Outlets O Design, construct, and stabilize all on-site conveyance channels to prevent erosion from the following expected peak flows: o "Channels must handle same peak volumetric flow rate as temporary pipe slope drains listed in Element 6, above. D Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent streambanks, slopes, and downstream reaches at the outlets of all conveyance systems. O The best method for stabilizing channels is to completely line the channel with a blanket product first, then add check dams as necessary to function as an anchor and to slow the flow of water. No stormwater runoff will be conveyed off site via channels, swales, or streams_ ELEMENT 9: Control Pollutants CI Design, install, implement, and maintain effective pollution prevention measures to minimize the discharge of pollutants. O Handle and dispose of all pollutants, including waste materials and demolition debris that occur on-site in a manner that does not cause contamination of stormwater. 0 Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other materials that have the potential to pose a threat to human health or the environment. On-site fueling tanks must include secondary containment. Secondary containment means placing tanks or containers within an impervious structure capable of containing 1 1 O%of the volume contained in the largest tank within the containment structure. Double-walled tanks do not require additional secondary containment. O Conduct maintenance,fueling, and repair of heavy equipment and vehicles using spill prevention and control measures. Clean contaminated surfaces immediately following any spill incident. 0 Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer, with local sewer district approval. Wheel wash or tire bath wastewater should not include wastewater from concrete washout areas. O Apply fertilizers and pesticides in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Follow manufacturers' label requirements for application rates and procedures. O Use BMPs to prevent contamination of stormwater runoff by pH-modifying sources. The sources for this contamination include, but are not limited to: bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, waste streams generated from concrete grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete pumping, and mixer washout waters. Adjust the pH of stormwater if necessary to prevent violations of the water quality standards. 0 Assure that washout of concrete trucks is performed off-site or in designated concrete washout areas only. Do not wash out concrete trucks onto the ground, or into storm drains, open ditches, streets, or streams. Do not dump excess concrete on site, except in designated concrete washout areas. Concrete spillage or concrete discharge to surface waters of the State is prohibited. Do not use upland land applications for discharging wastewater from concrete washout areas. O Obtain written approval from Ecology and provide to the City before using chemical treatment other than CO2 or dry ice to adjust pH. Version Date: October 7, 2019 Previous Version Date: February 20, 2019 ❑ Woody debris may be chopped and spread on site. I I Conduct oil changes, hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank drain down and removal, and other activities which may result in discharge or spillage of pollutants to the ground or into stormwater runoff using spill prevention measures, such as drip pans. ❑ Clean contaminated surfaces immediately following any discharge or spill incident. Emergency repairs may be performed on-site using temporary plastic placed beneath and, if raining, over the vehicle. Per BMP C154 a Concrete Washout Area is to be installed onsite to capture contaminated water from concrete washouts. To be installed prior to foundation/ concrete installation. BMP to be monitored daily and repaired as needed. Contractor is to provide spill prevention kits for excavation and concrete crews are required on Site. ELEMENT 10: Control De-Watering I I Discharge foundation, vault, and trench dewatering water, which have characteristics similar to stormwater runoff at the site, into a controlled conveyance system before discharge to a sediment trap or sediment pond. ❑ Discharge clean, non-turbid de-watering water, such as well-point ground water, to systems tributary to, or directly into surface waters of the State, as specified in Element S, provided the de-watering flow does not cause erosion or flooding of receiving waters or interfere with the operation of the system. Do not route clean dewatering water through stormwater sediment ponds. Note that"surface waters of the State" may exist on a construction site as well as off site; for example, a creek running through a site. ❑ Handle highly turbid or contaminated dewatering water separately from stormwater. L-I Other treatment or disposal options may include: 1. Infiltration 2. Transport off-site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters. 3. Ecology-approved on-site chemical treatment or other suitable treatment technologies. 4. Sanitary or combined sewer discharge with local sewer district approval, if there is no other option. 5. Use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized dewatering. ❑ Construction equipment operation, clamshell digging, concrete tremie pour, or work inside a cofferdam can create highly turbid or contaminated dewatering water. I Discharging sediment-laden (muddy) water into waters of the State likely constitutes a violation of water quality standards for turbidity. The easiest way to avoid discharging muddy water is through infiltration and preserving vegetation. If dewatering is needed all discharge will be directed to a temp_ sect_ trap BMP C240 prior to discharge to the city storm drainage system. The sediment trap will be designed for a typical 11,000 sf impervious area or 0.25 acres where the developed 2 year flow is 0.05 cfs X 2080 sf/cfc flow = 104 sf surface area plan or 10'x10'square surface pond area minimum. ELEMENT 11: Maintain BMPs ❑ Maintain and repair all temporary and permanent erosion and sediment control BMPs as needed to assure continued performance of their intended function in accordance with BMP specifications. ❑ Remove all temporary erosion and sediment control BMPs within 30 days after achieving final site stabilization or after the temporary BMPs are no longer needed. Some temporary erosion and sediment control BMPs are bio-degradable and designed to remain in place following construction such as compost socks. ❑ Provide protection to all BMPs installed for the permanent control of stormwater from sediment and compaction. All BMPs that are to remain in place following completion of construction shall be examined and placed in full operating conditions. If sediment enters the BMPs during construction, it shall be removed and the facility shall be returned to the conditions specified in the construction Version Date: October 7, 2019 Previous Version Date: February 20, 2019 documents. ❑ Remove or stabilize trapped sediment on site. Permanently stabilize disturbed soil resulting from removal of BMPs or vegetation. BMP to be monitored daily and repaired as needed and or as required by the City of Anacortes. Weekly reports are required to be submitted to the building department. ELEMENT 12: Manage the Project— Projects subject to Minimum Requirements 1-9 must have a Certified Erosion and Sediment Control Lead (CESCL) for site inspections. Projects subject to Minimum Requirements 1-5 do not require the inspector to be certified. By the initiation of construction, the SWPPP must identify the CESCL or inspector, who shall be present on-site or on-call at all times. ❑ Phase development projects to the maximum degree practicable and take into account seasonal work limits to prevent soil erosion and prevent transporting sediment from the site during construction. O Inspection and monitoring — Inspect, maintain, and repair all BMPs as needed to assure continued performance of their intended function. 0 Maintain, update, and implement the SWPPP. L.-I Clearing and grading activities for developments shall be permitted only if conducted using an approved site development plan (e_g., subdivision approval). L i From Oct 1 through Apr 30, clearing, grading, and other soil disturbing activities is permitted only if shown that the site operator will prevent silt-laden runoff from leaving the site through a combination of the following: 1. Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters. 2. Limit activities and the extent of disturbed areas. 3. Proposed erosion and sediment control measures. Weather conditions can influence the seasonal limitation on site disturbance. The City of Anacortes has the authority to take enforcement action per AMC 19.76 Stormwater. 0 The following activities are exempt from the seasonal clearing and grading limitations: 1. Routine maintenance and necessary repair of erosion and sediment control BMPs; 2. Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil 3. Activities where there is 100% infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. BMP to be monitored daily and repaired as needed and the responsibility of the owner. Project does require a certified CESCL. ELEMENT 13: Protect Low Impact Development BMPS ! If implementing any bioretention facilities or rain gardens, refer to the applicable BMP sections of the Manual for requirements. No LID BMPS are proposed. _Dale Herrigstad 5-20-2021 Applicant Signature Date Version Date: October 7, 2019 Previous Version Date: February 20, 2019 TAB 3 (MINIMUM REQUIREMENT #3) • 1-2.5.3 Minimum Requirement#3—Source Control of Pollution All known, available and reasonable source control BMP's must be applied to all projects. Source control BMP's must be selected, designed, maintained according to the reference Ecology Manual. The intent of source control BMP's is to prevent stormwater from coming in contact with pollutants. They are a cost-effective means of reducing pollutants in stormwater, and, therefore, should be considered in all projects. All Commercial Properties, Industrial Properties, and Multi-Family Properties, Boatyards, Sand and Gravel Mining Operations are required to comply with this Minimum Requirement. Refer to Chapter IV-2.1 Applicable (Mandatory) Operational Source Control BMP's Volume 4: Appendix IV-A: Urban Land Uses and Pollutant Generating Sources. Multi- Family Residences: Description: Multifamily residential buildings such as apartments and condominiums. The activities of concern are vehicle parking, vehicle washing and oil changing, minor repairs, and temporary storage of garbage_ Potential Pollutant Generating Sources: Stormwater contamination can occur at vehicle parking lots and from washing of vehicles. Runoff from parking lots may contain undesirable concentrations of oil and grease, suspended particulates, and metals such as lead, cadmium, and zinc. • S411 BMPs for Landscaping and Lawn Vegetation Management_ • S421 BMPs for Parking and Storage of Vehicles and Equipment. During construction of the site will be open and subject to erosion. BMP's as described in the erosion control plan and SWPPP must be constructed at the source to limit erosion and sediment laden runoff. The primary source for erosion is the driving path for the transportation of material to and from the site. A construction entrance from the alley and gravel construction route will limit erosion and silt laded storm water. BMP S411 Landscaping and Lawn/Vegetation Management will be utilized to limit Source pollution_ See BMP S411 at the end of this report. Version Date: October 7, 2019 Previous Version Date: February 20, 2019 TAB 4 (MINIMUM REQUIREMENT*4) • Minimum Requirement#4— Preservation of Natural Drainage Systems and Duffel's Natural drainage patterns shall be maintained and discharges from the project shall occur at the natural location, to 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 outfalls require energy dissipation. The objective is to preserve and utilize drainage systems to the fullest extent because of the multiple stormwater benefits these systems provide; and to prevent erosion at the downstream of the discharge location. Refer to the reference manual for supplemental guidelines and additional information under this section. Will this project disturb the Natural Drainage System or Outten of the project Site? NO. If yes, refer to section 12.5.4 for Supplemental Guidelines for additional information. No change in drainage is proposed for this site. Version Date: October 7, 2019 Previous Version Date: February 20, 2019 TAB 5 (MINIMUM REQUIREMENT#5) • Minimum Requirement#5—On-site Stormwater Management Project thresholds that trigger Minimum Requirements #1 through #5, shall utilize the On-site Stormwater Management BMP's from List#1 for all surfaces within each type of surface in List#'1; or, Demonstrate compliance with the LID Performance Standard. Projects selecting this option cannot use Rain Gardens. They may choose to use Bioretention BMP's as described in Chapter V-7 — Infiltration and Bioretention Treatment Facilities to achieve the LID Performance Standard. Refer to this section of the reference Manual for all Feasibility or Infeasibility Criteria for List#1 and List#2_ Is this project Flow Control Exempt? Yes (See Appendix /-E= Flow Control-Exempt Surface Water). If yes, provide reasoning from the applicability section of 1-2.5.7 Minimum Requirement#7: Flow Control). If No, then the project triggers Minimum Requirement#7 (1-2.5.7) and possibly Minimum Requirement#8 (1-2.5.8)_ The city has completed additional study for the downstream drainage capacity for basin F4 and determine that the capacity is available which would make this site flow control exempt. All sites are required to utilize BMP T5.13— Post Construction Soil Quality and Depth. If the project is Flow Control Exempt, select from the list below (Skip List 1 and List 2). o BMP T5.13 Post Construction Soils Quality and Depth o BMP T5.10A: Downspout Full Infiltration, or; o BMP T5.10B Downspout Dispersion Systems, or; o BMP T5.10C: Perforated Stub-out Connections, or; o BMP 1-5.11 Concentrated Flow Dispersion, or; o BMP T5.12 Sheet Flow Dispersion BMP 75.1 OA: Downspout Full Infiltration: The site is tight to the property lines and parking lots. Infiltration setbacks would not meet minimum requirements_ BMP 1-5.1 OB Downspout Dispersion Systems: Downspout dispersion requires a flow path of 50 feet or more and that is not feasible on this site. BMP 75.1 OC: Perforated Stub-out Connections: This is feasible and will be identified on the site plan for each building. BMP T5.11 Concentrated Flow Dispersion: Requires a flow path of 50 feet that is not feasible on this site_ BMP T5.12 Sheet Flow Dispersion: The dispersion area of 25 feet below a dispersion trench is not feasible. Version Date: October 7, 2019 Previous Version Date: February 20, 2019 The on site parking surface will discharge to a bioretention cell or swale with an underdrain in the northeast corner of the site. _Dale Herrigstad 5-20-2021 Applicant Signature Date Version Date: October 7, 2019 Previous Version Date: February 20, 2019 E3IVIP 11-5.13: Post-Construction Soil Qluadity amid Depth Purpose and Definition Naturally occurring (undisturbed)soil and vegetation provide important stormwater func- tions:including:-water-infiltration; nutrient,sediment,and pollutant adsorption;sediment and pollutant biofiltration; water-.interflow storage and transmission; and pollutantdecom- position.These functions are largely lost when development strips away native soiland vegetation and replaces it with minimal topsoil and sod. Not only are these important stormwater:functions lost,but such landscapes themselves become pollution generating pervious surfaces due to increased use of pesticides,fertilizers andother landscaping and household/industrial chemicals,the concentration of pet wastes,and pollutants that accompany roadside litter. Establishing soil:quality and depth regains greater stormwater functions in the past devel- opment landscape..,provides increased treatment of pollutants and sediments that result from development and habitation,and minimizes the need for some landscaping chem- icals,.thus reducing pollution through prevention. Applications and Limitations Establishing a minimum soil quality and depth is not the same as preservation of nat- urally occurring soil and vegetation.:However, establishing a minimum soil quality and depth will provide improved on-site management of stormwater flow and water quality. Soil organic matter can be attained through numerous materials such as compost,com- posted woody material, biosolids,and forest product residuals. It is important that the materials used to meet the soil quality and depth BMP be appropriate and beneficial to the plant cover to be established. Likewise,it is important that imported topsoils improve soil conditions and do not have an excessive percent of clay fines. This BMP can be considered infeasible on till soil.slopes greater than 33.percent. Design Guidelines Soil retention. Retain, in an undisturbed state,the duff layer and native topsoil to the maximum extent.praeticable. In any areas requiring grading remove and stock- pile the duff layer and topsoil on site in a designated,controlled area, not adjacent to-public resources and-critical areas,to be reapplied to other portions of the site where-feasible. Soil quality.All areas subject to clearing and grading that have not been covered by impervious surface, incorporated into a drainage facility or-engineered as struc- tural rill or slope_shall.,at project completion,demonstrate the following: 1_ AA topsoil layer with a minimum organic matter content of 10% dry.weight in .planting beds,and 5%organic matter content in turf areas,and a pH from:6.0 2014 Stomrwater Management Manual for Western .Washington Volume V-Chapter5-Page al-1 Version Date: October 7, 2019 Previous Version Date: February 20, 2019 to 8.0 or matching the pH of theundisturbed soil.The topsoil layer shall have a minimum depth of eight inches except where tree roots limit the depth,of incorporation of amendments needed to meet the criteria. Subsoils below the topsoil layer should be scarified at least 4 inches with some incorporation of the upper material to avoid stratified layers,where feasible. 2. Mulch planting beds with 2 inches of organic material 3. Use compost and other materials that meet these organic content require- ments a. The organic content for"pre-approved"amendment rates can be met only using compost meeting the compost specificationfo:r:BMP 77.30: Bio:retention Cells. Swaies,and Planter Boxes(p.959).,with the excep- tion that the compost may have up to.35%bio.solids or manure,. The compost must also have an organic matter content of40%to 65%, and a carbon to.nitrogen ratio below 25:1. The carbon to nitrogen ratio may be as high as.35:1 for plantings com- posed entirely of plants native to the Puget Sound Lowlands region.. b. Calculated amendment rates may be met through use ofcomposted material meeting (a.)above: or other organic materials amended to meet the carbon to nitrogen ratio requirements, and not exceeding the contaminant limits identified in Table 220-B.,Testing Parameters,in WAC 173-350-220. The resulting soil should:be conducive to the type of vegetation to be established. . Implementation Options:The soil.quality design guidelines listed above can be met by using one of the-methods listed below.: 1. Leave undisturbed native vegetation and soil,and protect from compaction during construction. 2. Amend existing site topsoil or subsoil either at default"pre-approved"rates, or at custom calculated ratesbased on tests ofthe soil and amendment. 3. Stockpile existing topsoil during grading,and replace it prior to planting. Stockpiled topsoil must also be amended if needed to meet the organic mat- ter or depth requirements,either at a default"pre-approved"rate or at cus- tom calculated rate. 4. Import.topsoil mix of sufficient organic content and depth to meet the require- ments. .20-14 StormwaterManagement Manual forWestem Washington Volume V-:Chapter 5.-Page 9 f 2 Version Date: October 7, 2019 Previous Version Date: February 20, 2019 More than one method may used on different portions.of the same site.Soil that already meets the depth and organic matter quality standards,and is not com- pacted,does not need to be amended. PlanninglPermittingl/nspectionNarification Guidelines &Procedures Local governments are encouraged to adopt guidelines and procedures similar to those .recommended in Guidelines and Resources For implementing Soil Quality-and:Depth BMP 75.13 in WDOE Stormwater Management Manual for Western VV'ashington. This document is available at: http:/iwww_soilsforsalmon.orgipdffSoil .BMP Manual.pdf Maintenance . Establish soil quality and depth toward the end of construction and once estab- lished.,-protect from compaction,such asfrom large machinery use,and from erosion. . Plant vegetation and mulch the amended soil area after installation_ . Leave plant debris or its equivalent on the soil surface to replenish organic matter. . Reduce and adjust,where.possible,the use of irrigation,fertilizers,herbicides and pesticides, rather than continuing to implement formerly established practices. Runoff Model Representation Areas meeting the design guidelines may be entered into approved runoff models.as "Pasture"rather than"Lawn." Flow reduction credits can be taken in runoff modeling when BMP T5.13: Post-Con- struction Soil Quality and Depth is used as part of a dispersion design under the con- ditions described in: BMP T5.106: Downspout Dispersion Systems(p..905) . BMP T5.11: Concentrated Flow Dispersion (p:905) . BMP T5.12:Sheet Flow Dispersion(p 908) . BMP T5.18: Reverse Slope.Sidewalks(p.937), . -BMP T5.30: Full-Dispersion (p.939)(.for public road projects) 2014 Stomiwater Management Manual for Western Washington Volume V- Chapters-Page G73 Version Date: October 7, 2019 Previous Version Date: February 20, 2019 Figure V-5.3.3 Planting bed Cross-Saction `C 7 4 -''- O ran i Loo5n.Boil with --- ♦t.ible dark organic matter matter - Loose or fractured Subsoil Reprinted from Guidarines and.Rasaurcas For impianranfing 5.11 Quaidy.and Depth 8MP 775.1.in'WDOE Storrmvatar:Miansgamont Manual forW.s-orin WmatlIrgton,'2010,Washington Organic Recycling Council NOV TO SCALE Figure V-5.3.3 Pia:nting Bed Cross-Section OE-PEA RT M'ENT OF Revised Jenuary:2016. E C'O L O G Y Pl>aee afte..1pY/ww...acy. e:gr.vrr-o pynlryl+t:htmrfcr copyngFd notice including per+ni6iioris StatlG oT':Washin plan Ymllstlon af NeblNty.,®ntl'tllaolalmec. 2014 Stormwate.r Management Manual for Western Washington Volume V-Chapter 5-Page 914 Version Date: October 7, 2019 Previous Version Date: February 20, 2019 Figure V-7-4.1Iks Typical Bioretention vv/Unc9erdrain Provide a 1.drop from the edge.of Provide a V'draP eidevralk from the edge of pavement 65M bottom.width varies.f•minimum Edge of pa marfl Ovaeflow entlPlPe C '51drwa)t or curbc+- rt _. pre..;- ^—, \a \.. �+, w _ 3"g�p rasac aggregate._arsod g••ooame conlPoet 6'to l2"' t'- -a� • ` � v In.ponolnH'.arca le Saoretention SOH Media(13•SM) \ .Mineral aggregate fNinaral a99ra9ale 1 yedemraln pipe bottom width to match IF ESN;bottom width Notes: 1. Scarify subgraee 3"rein.before bloretention soil Installation 2. .Compact 135M to 36%per ASTM 94.577 NorarU TC:vT•�r E Figure V-7.4.1 b Typical Bioretention w/Undercdrain DEPART Reveled February 201S ECOLOGY Pteaee eee:hpp/.Mevw.aey wa•gowbonyright.htmrfor copyrighl aefice.ira tedinH Permissions. State of:We shim:tan Hmltationof:aabNty'',arid disclaimer. 201.4 Stormwate:rManagement Manual for Western Washington Volume V--.'..Chapter 7-Page 962 Version Date: October 7, 2019 Previous Version Date: February 20, 2019 B 6—(MINUMUM REQUIREMENT 6 - RUNOFF TREATMENT) Refer to 1.2.5.6 and provide the required information for this Minimum Requirement. Threshold requirements for determining the applicability of runoff treatment. Projects in which the total of pollution-generating hard surface (PC>1-1.S) is 5,000 square feet or more in a threshold discharge area of the project, or Projects in which the total of pollution-generative pervious surfaces (PC;PS)-not including permeable pavements-is three-quarters(3/4) of an acre or more in a threshold discharge area, and from which there will be a surface discharge in a natural or man-made conveyance system from the site. The total Pollution-generating hard surface is propose to be 1,995 square feet of paved driveway and 1,905 paved alley for a total of 3,903 sf of PGHS and under the 5,000 square feet threshold requiring treatment_ The overall site is 14,999 square feet of 0.34 acres and under the 0.75 acre threshold. Runoff Treatment is not required but we propose including a 65 lineal foot bio-filtration Swale along the north boundary of the site to the east and discharging to the city storm system_ The swale will treat the driveway runoff area of 1,995 square feet. The alley will discharge directly to the enclosed drainage system_ Version Date: October 7, 2019 Previous Version Date: February 20, 2019 TAB 7 —(MINUMUM REQUIREMENT 7 —FLOW CONTROL) Refer to 1.2.5.7 and provide the required information for this Minimum Requirement. Threshold requirements for determining the applicability of flow control. - Projects in which the total of effective impervious surfaces is 10,000 square feet or more in a threshold discharge area,or • Projects that convert'/a acres or more of vegetation to lawn or landscape, or convert 2.5 acres or more of native vegetation to pasture in a threshold dis-charge area,and from which there is a surface discharge in a natural or man-made conveyance system from the site,or • Projects that through a combination of effective hard surfaces and converted vegetation areas cause a 0.10 cubic feet per second increase in the 100-year flow frequency from a threshold discharge area as estimated using the Western Washington Hydrology Model or other approved model and one-hour time steps(or a 0.15 cfs increase using 15-min11te time steps). The total proposed new or replaced impervious hard surfaces is 12,421 square feet and above the 10,000 square feet threshold discharge area. As discussed above the downstream drainage system has capacity for the full build out of this site. Flow Control is not required. Version Date: October 7, 2019 Previous Version Date: February 20, 2019 TAB 8 —(MINUMUM REQUIREMENT 8 —WETLAND PROTECTION) Refer to 1.2.5.8 and provide the required information for this Minimum Requirement. The site discharges directly to Fildalgo Bay with no wetland downstream of this site. TAB 9—(MINUMUM REQUIREMENT 9—OPERATION AND MAINTENANCE) Refer to 1.2.5.9 and provide the required information for this Minimum Requirement. Constraction Criteria The biofaltratien swale should not be put into operation until areas of exposed soil in the contributing-drainage catchmont have been sufficiently stabilized. Deposition of eroded soils can impede the growth of grass in the Swale and reduce swale treatment effectiveness. Thus,effective erosion and-sediment control measures should remain in place until the swale vegetation is established.(see Volume 7I for erosion and sediment control:Bh4Ps). Avoid compaction during construction. Citsde biofilters to attain uniform longitudinal.-and lateral slopes Maintenance Criteria Inspect biofiltors at least once every 6 months,.preferably during storm events,and also.after storm events of>0_5 inch rainfall/24 hours. Maintain adequate grass growth and eliminate bare spots. .Mow grasses,if needed for good growth {typically maintain at 4—9 inches and not below design flow level(King-County,1.998)}_ • Remove sediment as needed at head of the swale if grass growth is inhibited in greater than 10 percent of the swale,or if the sediment is blocking the distribution and entry of the water(King County, 199.8). ▪ Remove leaves,litter,and oily materials,and re-seed or resod„and regrade,as needed. Clean curb cuts and level spreaders as needed. Prevent Scouring and soil erosion in the bio£ilter.if flow channeling occurs,regrade and reseed the biofiilter,as necessary. Maintain access to bio.filter inlet,outlet.and to mowing.(Figure 9.8) • If swale is equipped with:underdrains,vehicular traffic on the swale bottom(other than grass snowing equipment)should be avoided to prevent damage to the drainpipes. Au it R Rrr Air � TT ' K. J2'l B EET --_ _� U eWSI41 _0.0(9Atat • om�sn 5 AYNW L 30 - z it=t2 !�'t_. av:A'.s 6 wti, ,y...__.__—-___ - tl�AI IN) .T t ,.- W.vu n ,, C` a sar t T ��: :p -1—IT 1 ei ' I 1 ! . '1 ! t I • 7 6I9is 2? 1 1 4.7 i 12 i II { 9 ! 8 ! LOf E LOT 0 I 0AF u� ` we wcl T a u taI wn Pill per, s ass ttsu etu vs:n v p� ! LOT r .LOT B kLOT A n EKea ,�v w5271,0'•�"�7fE° j 8?1 I BII .Knu�F w I 1 A I ry g I= 4 W 1 ,:9Rp�IIA��A� I ` � a J I_,. 2 zis 101 ! I I v z ' LI ate > ` ��, -'�—L--9-- it 1 -�'� �-E °.1 aJS ' IR 4 _ ++w A4.wKatz a I it T I 1 t«� µw.m. 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BbNRPRY Llt£ AOTMFNT SA hYOft'$ g1tCtTE HERRIGSTAH 3?d Street 6 R Avenue, 3 gg DEE tOk � R32Street LLC Buck ISILE EI4i Da �� "9" ENGINEERING AND SURVEYING. �� * . ,mac a7 a ke on f'um awn cam�X ��1'Q— co gNs i?td Y3ISILE L POd0 gypp rH15t16 LAMP ROAD, AN13bR4&4 VA I� �a Tmo m,-x 1 4.. 2MOTES6-299-a YA 93221 p,U x ,hax pHUNB UCE 28, SC x aO It aut A aty 3ar2i9-6P.CV Av t xa y ai[If. MI I P NN T1.7,4•id� am ---- -, MN:1 0 Z W a a Q APPENDIX 2 —Soils AnayIsis (Volume 1, Chapter 3.1.1) s 10.. ♦� S � Souls Report o w, Linda Spicher, Septic.System Designer a-- b y` ?? License 5100294 ,..7 . siA 's�- (360)708-.3004 s�/�:4_te 6+Gh1ER 44. ,\ �\\LO, z D9.29..,� Project/Client: Landed Gentry Homes.+&Communities Page / of Contact Steve Baughn Property Owner: Jennings Revocable Living Trust Site Address: 806'33rd Street,Anacortes,WA Parcel Number: 60575 Date on Site: 5/11/2020 Map Unit, Natural Resources Conservation Service: #20 - Bow-Urban land oomplex, O to 8%slopes Hydrologic Soil Group: C/D Soil Type' Loading Rate2 Soil Loci 1 0—6 gravel, imported 1 1.0 6--20 dark brown fine sandy loam 4 0_6 20—38 tan sandy clay loam, no roots, mottles, dense 6 0.2 anticipated water table at 20" Soil Log 2 0—5 gravel, imported 1 1.0 5—1�6 dark brown fine sandy loam 4 0.6 16-22 tzan sandy olay loam, roots, mottle.. 6 0_2 22-.36 tan loamy clay, mottles 7 not suitable anticipated water table at 16" One of seven numerical classifications offine earth particles and rock fragments as described in WAC 247-272A-0220(2)(e). 2 From Chapter 247-272A NA/AC: "Hydraulic Loading Rate"means the amount of effluent applied to a given treatment step.In this chapter expressed as gallons per square foot per day(gal/sq.ft./day). ir 1 g� a ---1 t -. _ - -..... a . 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J� HC+t 5/19/2027 Conservation Service National Cooperative Solt Survey.���"+�p�yt Nige ga'1 of 3 F CPINFS 07-29- ,Z;, Version Date: October 7, 2019 Previous Version Date: February 20, 2019 Skagit County Area, Washington 20—Bow-Urban land compllex..O to.8 percent slopes Map Unit Settina • National map unit symboi: 2hvl • Elevation: O to 450 feet 11 • Mean annual precipitation: 20 to 60 Inches • - • Mean annualair temperature: 48 tO 50 degrees F ;r. - 1� • Frost-free.period: 150 to 220 days • Farmland classification: Not prime farmland 11 Map Unit Composition • • Bow and similar soils: 60 percent • Urban land: 35 percent 1� • Minor components: 5 percent • Estimates arebased on observations,descriptions, and.transeets or:the mapunit. Description of Bow Setting • Landfarm:Terraces, hilisiopes • Parent material: Volcanic ash, glaciolacustrine deposits, and glacial drift Typical profile • HI - O to 7 inches: gravelly ashy loam 142- 7 to 37 inches: very gravelly ashy loam • hi3- 17 to 31 inches: day loam • H4-.31 to 60 inches: silty clay Properties and qualities • Siope: 0 to 8 percent • Depth to restrictive feature: More than 80 Inches • Natural drainage class: Somewhat poorlydrained • Capacity of the most limiting layer to transmit water(Ksat): Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water tablet About 6'to 18 inches • Frequency of flooding: None • Frequency of ponding: None • Available water storage 1n profile: High (about 1.0.4 Inches) Interpretive groups • Land capability classification (irrigated): None specified • Land capability classification (nonirrlgated): 4w • Hydro/ogic Soil Group:C/D • Forage suitability group: Seasonally Wet Soils (G002XN202WA) • Hydric soil rating: Yes Description of Urban Land Interpretive groups • Land capability classification (irrigated): None specified • .Land capability classification(nonirrigated): 8 Hydric.soil rating: No JVIInor Components Bellingham, undrained • Percent of map unit: S percent Land farm bepressions • Hydric soil rating: Yes Version Date: October 7, 2019 Previous Version Date: February 20, 2019 APPENDIX 3—Model Soil Management Plan for BMP T5.13 An alternate document acceptable to the City of Anacortes is a Test Report provided by the Soils Supplier that identifies the soils to be used meet the specifications outlined under Minimum Requirement 5. The specifications are in both WSDOT and CSI Formats. For specifications, refer to the above referenced PDF. This submittal can be a deferred submittal since most projects are not sure who the supplier will be at the time of building permit application. For projects that trigger Minimum Requirements 1 through 5, the Test Report will be provided to the Building Department. Projects triggering Minimum Requirements 1 through 9, the Test Report will be provided to the Engineering Department. DEFERRED SUBMITTAL: PROVIDE A TEST REPORT FROM SOILS SUPPLIER TO THE BUILDING DEPT. Version Date: October 7, 2019 Previous Version Date: February 20, 2019 PROJECT INFORMATION "Model Soil Management Plan for BMP T5.1 3" age#_of pages Complete all information on page 1;only site address and permit number on additional pages. Site Address/Lot No.: 3804 N Avenue Permit Type: Permit Number. Permit Holder: Phone: Mailing Address: Contact Person: Phone: Plan Prepared By: ATTACHMENTS REQUIRED(Check olrrequired items that are attached to this plan) Site Plan showing,to scale: _Areas of undisturbed native vegetation(no amendment required) _New planting beds and turf areas(amendment required) Type of soil improvement proposed for each area Soil test results(required if proposing custom amendment rates) Product test results for proposed amendments AREA# (should match Area#on Site Plan) PLANTING TYPE Turf Undisturbed native vegetation Planting Beds _Other: SQUARE FOOTAGE OF THIS AREA: square feet SCARIFICATION _inches(depth)of scarification needed to achieve finished total 12"loosened depth. _Subsoil will be scarified PRE-APPROVED inches of compost or imported topsoil applied AMENDMENT METHOD: X 1.1 (conversion factor, inches to cubic yards) PRODUCT: _Topsoil import =cu.yards per 1,000 sq.ft. _ _Amend with compost X ,000s sq.ft.in this area _Stockpile and amend =cubic yards of amendment —s QUANTITY: CU.YDS. ( cu.yds.stockpiled) (needed to cover this area to designated depth) _ CUSTOM AMENDMENT Attach test results and calculations. _Topsoil import inches organic matter or topsoil import PRODUCT: Topsoil 8c compost lift X 3.1 _Amend =cu.yards/1,000 sq.ft. _Stockpile and amend X ,000s sq.ft.in this area ( cu.yds. stockpiled) =cubic yards of amendment QUANTITY: CU.YDS. MULCH ,000 sq.ft_ PRODUCT: X 6.2 (conversion, to give 2 inch mulch depth) =cubic yards of mulch —s—s—. QUANTITY: CU.YDS. TOTAL AMENDMENT/TOPSOIL/MULCH FOR ALL AREAS(complete on page I only, totaling all areas/pages in this Plan) 0 Product#1: 0 Quantity: cu.yds. O Test Results: °A,organic matter C:N ratio d5:1(except mulch,or<35:1 for native plants) "stable"(yes/no) 0 Product#2: 0 Quantity: cu.yds. 0 Test Results: ^r6 organic matter C:N ratio 45:1 (except mulch.or G35.1 for native plants) "stable"(yes/no) 0 Product#3: 0 Quantity: cu.yds. O Test Results: ^fo organic matter C:N ratio Q5:1(except mulch,or<3.5:1 for native plants) "stable"(yes/no) Date: Inspector: Approved: Revisions Required: Date: Inspector: Approved: Revisions Required: Version Date: October 7,2019 Previous Version Date: February 20,2010 APPENDIX 4—Determining Construction Site Sediment Damage Potential (Appendix 7—NPDES Phase 11 Permit) Note: See attached. All projects within the City of Anacortes are required to complete that document under Appendix 4. Western Washington Phase II Stornawater Permit i_ APPENDIX 7 - Determining Construction Site Sediment Damage Potential The following rating system allows objective evaluation of a particular development site's potential to discharge sediment. Permittees may use the rating system below or develop alternative process designed to identify site-specific features which indicate that the site must be inspected prior to clearing and construction. Any alternative evaluation process must be documented and provide for equivalent environmental review. Step one is to determine if there is a sediment/erosion sensitive feature downstream of the development site. If there is such a site downstream complete step two, assessment of hydraulic nearness. If there is a sediment/erosion sensitive feature and it is hydraulically near the site then go to step three to determine the construction site sediment transport potential_ ii. GTFP 1 —Rudiment/Frn�ion Sensitive Features Identification Sediment/erosion sensitive features are areas subject to significant degradation due to the effect of sediment deposition or erosion. Special protection must be provided to protect them. Sediment/erosion sensitive features include but are not limited to: i_ Salmonid bearing fresh water streams and their tributaries or freshwater streams that would be Salmonid bearing if not for anthropogenic barriers; ii. Lakes; Category 1, II, and III wetlands; iv. Marine near-shore habitat; v. Sites containing contaminated soils where erosion could cause dispersal of contaminants; and vi. Steep slopes(25% or greater) associated with one of the above features. Identify any sediment/erosion sensitive features, and proceed to step two. If there are none the assessment is complete. �STFP 9- Hyti rar�lir: Nuarnuvs A4�uvvmunt Sites are hydraulically near a feature if the pollutant load and peak quantity of runoff from the site will not be naturally attenuated before entering the feature. The conditions that render a site hydraulically near to a feature include, but are not limited to, the following: i. The feature or a buffer to protect the feature is within 200 feet downstream of the site. ii. Runoff from the site is tight-lined to the feature or flows to the feature through a channel or ditch. August 1, 2013, Modified January 16, 2015 Appendix 7- Determining Sediment Osmage Potential Page 1 of 3 Version Date: October 7, 2019 Previous Version Date: February 20, 2019 A site is not hydraulically near a feature if one of the following takes place to provide attenuation before runoff from the site enters the feature: iv. Sheet flow through a vegetated area with dense ground cover v. Flow through a wetland not included as a sensitive feature vi. Flow through a significant shallow or adverse slope, not in a conveyance channel, between the site and the sensitive feature. Identify any of the sediment/erosion sensitive features from step one that are hydraulically near the site, and proceed to step three. If none of the sediment/erosion sensitive features are hydraulically near the site, the assessment is complete. vii. STFP 3—Construction Site Sc+dimc nt Tranaoort Poten*1a( Using the worksheet below, determine the total points for each development site. Assign points based on the most critical condition that affects 1 0%or more of the site. If soil testing has been performed on site, the results should be used to determine the predominant soil type on the site. Otherwise, soil information should be obtained from the county soil survey to determine Hydrologic Soil Group (Table of Engineering Index Properties for step 1_D)and Erosion Potential (Table of Water Features for step 1.E) When using the county soil survey, the dominant soil type may be in question, particularly when the site falls on a boundary between two soil types or when one of two soil types may be present on a site. In this case, the soil type resulting in the most points on the rating system will be assumed unless site soil tests indicate that another soil type dominates the site. Use the point score from Step 3 to determine whether the development site has a high potential for sediment transport off of the site. Total Score Transport Rating <100 Low ❑100 High A high transport rating indicates a higher risk that the site will generate sediment contaminated runoff. Construction Site Sediment Transport Potential Worksheet A.. Existing slope of site (average, weighted by aerial extent): Points 2%or less .. O >2-5% 5 >5-1 0% 15 >10-15% 30 >15% 50 B. Site Area to be cleared and/or graded: <5,000 sq. ft 0 5,000 sq. ft.—1 acre 30 >1 acres 50 C. Quantity of cut and/or fill on site: <500 cubic yards O 500—5,000 cubic yards 5 >5,000— 10,000 cubic yards 10 >1 0,000—20,000 cubic yards 25 >20,000 cubic yards 40 I7. Runoff potential of predominant soils (Natural Resources Conservation Service): Hydrologic soil group A 0 Hydrologic soil group B 10 Hydrologic soil group C 20 Hydrologic soil group D 40 E. Erosion Potential of predominant soils (Unified Classification System): GW, GP, SW, SP soils 0 Dual classifications (GW-GM, GP-GM, GW-GC, GP-GC, SW-SM, SW-SC, SP-SM, SP-SC) 10 GM, GC, SM, SC soils 20 ML, CL, MH, CH soils 40 F. Surface or Groundwater entering site identified and interceptedl: Yes 0 No 25 G. Depth of cut or height of fill >10 feet: Yes 25 No 0 H. Clearina and gradina will occur in the wet season (October 1 — May 1): Yes 50 No 0 TOTAL POINTS 95 1 If no surface or groundwater enters site, give 0 points. APPENDIX 5—Site Plan with all applicable information (Minimum Size 11x17 at a legible scale) SEE FULL SIZE ECS PLAN APPENDIX 6 —Documented Site Photos (Show all directions of the site, including frontage) Location: 32nd & R Avenue Description of the photo: Site from Alley and R Avenue Photo t.alcen by: Dale Fierrigstad, 5-20-2021 .1 -xr• _ • - f t - - , • - „ - , _- • - r , -44 ---- • - ; t.vP.,7` fr. ,„ )-,) - ^ _ • _ • _ v.fl<4.z= a' ' • I -r" , • -.5' - _ I,%I 7 " 1 " . " - _ " - - 4.; 4-1;. ", • , -1;.,1 ft4.0.44 • -4- 4 L Xyryf, ;v4,`r - s� .. t �� -ry�h'z9z"- -e a: .: {<�" 'vA�." a; .—r tt"w `{ z5 E ' .k �3�7, y; o • "V i v E'�,^f}"*. cy � , `�_Y. T�'•¢`�"� , W# 1.t f sK l_`?.',i rr yy ,-•,.'wwm',.. .y,Y,V , sir _> • t ,. LI i t - 5to, t :. s+ k. �ry was.., vi4Mr -.,�. • eL.. _ "Ga`F sea•rt 'R�Ni ;! +yy e "Y` r /� � -7! Y :C S - ;... �'lY-c'dI ' � • .=V2a G �U err z ,x�'� e a?v. '...�,� + �c� ,r.. 4-, ^;,;�— ,.., i.. ., a_ ry.`e.".... ..•..::. .,.�..— •, .e'er.':,,:5. .. -...__ _ - .. APPENDIX 7— Drainage BMP Facility Maintenance Covenant Note: To be recorded prior to: 1)Temporary Certificate of Occupancy; 2) Final Certificate of Occupancy, and or; 3) Final Acceptance of the project. This is Covenant is required for any Permanent Stormwater Facility constructed on a project site. The applicant should work with the the City of Anacortes Engineering Department on formalizing the document for recording.