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Permit File BLD-2021-0730 3206 R Avenue (12)
x txE:RRIGS), _ Vain' PY�ty4 WAS!/lN V �� I �`!"`��_ o�=� �' '; Storm Water Drainage Report inimum Requirements 1 through 9 yauut �,' ENGINEERING DEPARTMENT RGatst`c�'� � � 2�._.J "j.7 Z-� 904 6t^ Street Anacortes, WA 9822'I �'a. SSION ni �' ">- Www.an acortaswa.aov Official Use Only: (Information [a Inspectors 3 Required Storm Water Facility and other related raq uirements: _'�� T- s . t o� - r'�2-F'e�c+�.ti� � PaG� cc�. t�.�zTo._J �P T'"l . 3 � - t3to - T �J �Q TS. ("� — �IL�S = r� 541�t�RZw9.t>.arnc�] KLT— tYr2>'Z— — �I Project Address: _32"O 8. R Avenue Submittal Data: Orl - Zo - Zo2l Parcel Number P6D566 Revision Number: 3- Gwt LS - Parmit Number: _BLD-2D2'1- Reviewer: / iL+> ; o52x¢� Acceptance�D�ta (COA): o0.c2o-2oZ1 S� F-RONT OF REPORT: �i �- tL� Submittal Checklist: (All items listed below era. req uirad fpr a com�pl¢te s^u-b^mitts l) > Cover Sheet (Praparer to Provide): Project title. Location, Revision dates, Engineer's Stamp u TAB 'I t Minimum Raquiremant #t -Preparation of Stormwatar Site Plans o TAB.2: Minimum Raquiremant #2 -Construction Stormwater Pollution Prevention (SWPP) o TAB 3 Minimum Raq uirament #3 -Source Control of Pollution o TAB 4: Minimum Raq uiremanY#4 -Preservation of Natural Drainage Systems and Outfalls o TAB S: Minimum Requirement #5 - On -site Stormwatar Managamants o TAB 6: Minimum Raq uirament #6 -Runoff Treatment o TAB 7: Minimum Raq uirament #7 -Flow Oontrol o TAB 8: Minimum Raq uirament #8 -Wetland Protection o TAB 9: Minimum Raq uirament #9 -Operation and Maintenance a APPENDIX -I -Survey pertormed by a Professional Lantl Surveyor o APP EN.DIX 2 - Soils.Analysis (Volume t, Chapter 3. t.1) o APPENDIX 3 - Motlel Soil Management Plan {or BMP T5.'13 o APPENDIX 4 -Determining Construction Site Sediment Damage Potential (Appendix 7) o APPENDIX 5 - Sita Plan with all applicable information (Minimum Size t tz17- 30 scale) o APPENDIX 6 -Documented Site Photos {North, South, East and West) o APPENDIX ] - Orain age BMP Facility Maintenance Eovanant, ifi applicable. To be recorded prior to the Temporary. Oertificate of Occupancy, Certificate of Occupancy or Final Acceptance. FLOW CONTROL EXEMPT Starmwater Management Requ irements: l/ersion Date: October 7, 20'19 Previous Version Date: February 2D. 20'I9 o Refer to the 20t2\t4 Department of Ecology Manual, as amended in 20t4 For fu rthar required information. o See also, City of Anacortes Municipal Coda t 9.76 for additional information o See also, current Engineering Development Standards, Chapter 2- Storm Drainage for additional information. P roiact Descriotfon and Summary: Summary Table Existing Proposed Development Type Untlevelo ed Multifamil Number of Lots � Lot Acreage in SF t4,999 SF Soil Types) Bow Urban Land Complex HG C/D Site Sediment Trans ort Score Hi h\Low Low 95 Low 95 Depth to Ground Water Table (Feat and Inches) Sea com /ated So/Is Ana/ sis o/ume 1 Ch tar 3. 9. 9 Under 20' Infiltration Rata during Rainy Season (Inch\Per Hour) N/A Im ervious Surface on -site O t0,644 sf Impervious Surface (off -site) O O New and Re laced Hard Surface TOTaI SF O t O 644 sf Lot Covara a Percents e O 70 BMP (Required Minimum Requirement 5) BMP TS.t 3 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 Sita Conditions Summary: (Additions//y, provide information on pr>3 vious pannits, if any, /ilca Grads and Fil/, Clear and Grade, topog/aphy, vegetation, drainage, Critics/ Areas adjacent to the site and how it may affect this project if soi/s era disturbed, Soi/s Typa (!nc/uded in Soi/s Ana/ysis Report), Erasion 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 comer of the site to the northeast corner of the site at approximately 4.5 % . A single family home lies to the west. Tha north (32ntl Street) and east (R Avenue) frontage has an existing sidewalk with curb antl gutter. An existing storm systems lies along the north 32^' 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: (Additions//y, to be shown on the sit® p/an. Identify cuf and fi/l areas, proposed s/opes of a// haul 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 Gomp Pian - Gity website\publicworks\engineering\comprehensive plans): What Drainage Basin are you in? F4 Identify any tlownstream 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, 20t9 Previous Version Date: February 20, 20t9 northeast corner of the site_ The storm drainage system from here to Fidalgo Bay is an enclos¢d 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 compiet¢d additional flow volum¢ study and came to the conclusion that the down stream system has capacity for the typical storm event in Anacortes. Complete th¢ Applicability Requirements —Flow Chart (Figure 1-2.4.'I Attached, Figure I-2.4.2 Attached and Figure I-2.5.'I Attach¢cn Version Date: October 7, 20'19 Previous Version Date: February 20, 20t9 Figure 1-2.4_1 Flow Chart for Oetermin ing Requirements for New Uevefopment Siart H¢re noes <ne �rte name 3s9:, or e.isiing - mpa rage. No ooee the p��i�� row orc m e.aoo square r®et greater, or Haw Plus repla�.aa nnm en«aoe Y0S All Min Ymum Require apply to tM1en antl replaces Hard surfaces ana cowzrted vegetation areas. augtl ibappry to tM1e nrn antl mplacetl M1ard surfaoee ana me Iona aiatumad. SSCRedevelopmen['Min imu m Rapun.¢manfs ana riow cr.an (Figure 1-2:9.2J. No ooes�.tneiprpept result In 2.00D squaro ipaf,-or greater, otnawplus. raplawd Itartl surtace area't 1No Does tltB P JeC Fays land disturang: acivaiaa af'],OQO aquaia faa4orgraHTa(I No Flow Chartfor Determining Req uire ments for New.DevelDpment EGOLOG 20 t4 Sto[mwater Management Manua/ for Western Washington VOIumeY-Chaptar.2-Page 37 Version Date: October 7, 20t9 Previous Version Date: February 2D, 20t9 TAB 'I (MINIMUM REQUIREMENT #'I) t-2.S.t Minimum Requirement #t — Prepare a Stormwater Site Plan - 'I .3 —Preparation of a Stormwater Site Plan - 'I .3.t — Stormwatar Site Plans: Step -by -Step Notes: The lava/ of detail needed for each step depends upon th¢ proj¢cf size. Provide a narrative description of each step. t-3.'I.t Stap 'I -Site Analysis: Collect antl Analyze Information on Existing Conditions Sites analysis shall be submitted as part of the Existing Conditions Summary above. Part of the information in this step should ba 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 intendatl to compliment the predeveloped conditions of the site. A Stormwatar 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 properly is developed with single family homes. The soils report was completed for the pro party just to the south of this site and is included in Appendix 2 identifies the soils as Bow Urban Land Complex Hydrologic group C/O with a anticipated water table from t6" to 20" in depth. The soils do not allow for infiltration. 'I-3.t 2 Step 2 -Prepare Preliminary Development Layout Basal upon the analysis of existing site conditions, locate the buildings, roads, parking lots, landscaping features, on -site stormwaiar management BM P's, antl preliminary location of stormwatar 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 CtOTj. Grading will only be in the area of the house foundation and exposed to erosion until the foundation is complete and backfill¢d. Version Date: October 7, 20t9 Previous Version Date: February 20, 20'19 'I-3.'I .3 Step 3 -Perform Off -site Analysis (at Local Agency's Option): Use additional Sheets, if necessary, Ecology recommends that local governments raq uire an off -site analysis for projects that add 5,000 SF or more of new bard surfaces, or convert'/. acres of vegetation to lawn or land Scapa areas, or convert 2.5 acres of for¢st¢d area to pasture. Off -site analysis extends to '/. mile downstream of the project site. Two catch basins are located in the curb line at the northeast corner of the site at 32n° Street and "R" Avenue. The storm drainage system from here to Fidalgo Bay is an enclosed storm pipe for a dista nca of 2,B7fi feat. t -3.t.4 - Datarm ine Applicable Minimum Requirements Establish project size th r¢sholds for the application of Minimum Raq uiramants to new development and redevelopment projects. Figures 2.4.t (Attached) and 2.4.2 (Attached) provide the same thresholds in a flow chart format. Barad on the preliminary layout, determine whether Minimum Requirements #t through #5 apply to the project- or, whether Minimum Requirements #'1 through #9 apply. Please note, that Minimum Requirement #t through #5 may trigger additional Minimum Raquir¢mants, such as Flow Control. The total n¢w impervious area added to this site will ba � 0,B44 square feet and over the 5,000 square foot threshold and triggers minimum requirements t through 9. t-3.'I .5 Step 5 - Prepares a Pannanant Stormwater Control Plan (Refer to this section of the Eco/ogy Manua/ 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. t -3.'I .6 Step 6 - Prepare a Construction Stormwater Pollution Prevention Plan (MR#2 — t3 Elements) Refer to Chapter //-3 — P/arming fora detai/ed description of each a/amen(. See a/so attached Tables 4. 0. f (Source Contra/ BMP's by SWPPP E/amant) and Tab/a 4.2. f (Runoff Conveyance end Treatment BMP's by SWPPP E/ement). See attached t 3 Elements of a SWPPP, please complete and attached 7-3.t.7 Siap 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, 20t9 Previous Version Date: February 20, 20t9 • 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. (Sae attached Drainage BMP Maintenance Covenant BMP Agreement) • Declaration of Covenant for Privately Maintained On -site Stormwater BM P's (See attached Drainage BMP Main tanance Covenant BMP Agreement) • Bond Quantities Workshaat, 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. t -3.t.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 Sita Plan should ba reviewed to check that these requirements are satisfied. To take place during review and during and after construction. Version Data: October 7, 20t9 Previous Version Date: February 20, 20t9 TAB 2 (MINIMUM REQUIREMENT #2) t-2.5.2 Minimum Requirement YR2 —Construction Stormwater Pollution Prevention Plan (SWPP) - All projects are raquiretl to complete Minimum Requirement 2. - Refer to the t 3 Elements of the SWPP (Sae document below, complete and attach) - Sea attached Table 4.t.t, Table 4.2.t and Table - Provide Engineering Calculations as an attachment For Sediment Ponds\Traps, Diversions, Wat¢rways and RunoTf/Stormwater Detention Calculations. Table 4.1.1 Source Control BMP's by SWPPP Element Version Date: October 7, 20t9 Previous Version Date: February 20, 20t9 EE�bR Yn�rB6 ESYWb Yr:mmR EProYef EYone1P EY:vNM1 EYnoRPtR EN:snrN] BYP er Ebnen[Ms:R Pr��ry� Cant®1 YYrYIr� YylnpPtlrn Prvbe<IaM M9MIenlYsi. C udYa b4 YbP� PWms:b BYM1 P:n)nm ImMR BYP C1M:Poar�bg MaanalYrg�reBen ✓ YYP CYfb Bufbr lure ✓ ✓ BYP C1Oi N1yF VYIEYY PYrfbm Y�I✓f ✓ ✓ BYP C105: SYMEwtl Gr�arrRbn ✓ EnRamlEah BYP GIBE: NYwIMVY ✓ BYP CYEi: Camlrucibn POWIPakEp ✓ Pran Ewum.n YYP C1'm:Ta:rgarry�tl 0.r::s:s:! ✓ ✓ fnaal YYP C1l�e YnipbE ✓ ✓ YYP C1Y8 Xnb �b Ylnbrb ✓ ✓ YYP Clile Plea¢ CeYRR:q ✓ YYP CIY: MWI:q ✓ YYP CY%x TEpPlllwp /CanYotYe ✓ YYP LYi: PegsnEY1EYB Yr fall Er®ba ✓ P:uruRb. YYP cm: BnRr Ya:Ybmlep ✓ ✓ YYP G'IMe 6raaYnlTanne� ✓ ✓ YYP CYtl: OUYCsnRN ✓ YYP G1Ba1 YaYrYY Oa M�:a ✓ ✓ OYP CYBY: GrRVM X�ralbp ✓ YYP C112e SssRWq �d lrReYp ✓ PaWrbn P:wanYm: YYP CIEI: YnYrYI YeMq. YYr4 �d ✓ CanYlnuY BYP C1EY Gm�W Nbnl:nul M'nn ✓ YYP ptl: GREYGEranbnaW ✓ ✓ YtlESY G::ImI Wd eYP C1BEe aeE.aue:B I Table 4.2.1 RunofF Conveyance and Treatment BMP's by SW PPP Element Version Date: October 7, 2019 Previous Version Date: February 20, 20'19 --.. __.__ BKP mElenvelwm F_W �r�enM1 Y.4 Cnnv61 Flrrw'.RMvs. me..#:w Inefrll 9aitlMrren[ FJe�MM11E Pvnlr�uK SlnPae EINrPEnth PFVMu BcuSR t�Aeaz rxemanL CA BYPh1I2u CZlavmu4 B Ya PeenArti 5 ConSml P�iiRmis cl¢rrcn(#46 Cantrnl aa. WeL rlvep P_I.mlePcws Pmiwc4 Law 1¢Peat ].vv¢Y rent. �_ cep: MMImPiae QiM nraa. SYmlr�— J d BMP C'}11M1: 6figne-0.Ynatl GAaaamlA +t aYfP G9IS OY ee�9til L9rYNy - v" BMP CEO®: 1MMr6yIIF '✓ d ' BMP csnu:. wywarape ormnc d BMP GyO'L:. StlPaiaiaor. Cmr� - � ✓ , aMP C20% CYrrlcSc.C»ro ✓ a! 9MP G4Yt: TNanBPlar9kOiB� EnoawB OAotiY OauQ �. 'BMP C204 OwYLae. ReeMaMelY w'" aMP C32G: Storm @min lmNl P�dHOYPs ✓ BMP C23t: 6enul� Beniev J d BMP CY4Y 4mw1 PoILer @Pmr J BMP p.9iS Blh Fmnao ✓ ✓` ®MP Gi44' MiZrAYWf6®L'YL d i BMPGEiSC M1FN. IEIYi d . ®MP GSdfiC'1P®�'�VEiiO PNbRt1ML ✓ BMP C2aOc 9pfhatnnE Trspr ✓ r/ BMP G,aaea Twr�eery SaefrrwK Pbntl ✓ I BMP GY.G¢ GarralrrwelbP Smemaalary ctlrPuuAYweM�nM f. BMP 6261r ConalrvdOmx atarr:�we[er FIOeMInw 0MP C?S2 YR5LIi PH MSwArMh' VOA EIkfYML w._ ,� BfIIP GSSi-P�'1 ConerW Spr HIeb:PH 1Mvrer � Version Date: October 7, 20'19 Previous Version Date: February 20, 20'19 13 Elements of SW PPP (Construction Stormwater Pollution Prevention Plan) Please check off boxes to show that each element has been road and understood. Provide details where applicable and if certain aspects are unnecessary or exempt, cleary justify. Details of the t3 Elements and the correlating BM Ps are listed Above from the 20t4 Stormwater Management Manual for Western Washington (SWMMWW). A link is provided on the City of Anacortes websha, under Planning, Community, S Economic Development Department, as well as under Stormwater on the Engineering Division of Public WorK's page. Owner Name: R32 LLC Site Address: 3204 R Avenue Prepared By:Dale Herrigstad PE The Stormwater checKiist or building permit determined that: o The t3 elements must be addressed for construction activity atlding under 2,OD0 sq. ft. of hard surface area. 0 These elements must be addressed for construction activity adding 2,000 sq. ft. or more of hard surtace area. This means that an attached narrative and site plan are required with this document. r ach elaman rovid¢ th¢ BMP's the wil 1 b a r ro act. Us¢ th¢ attached Tables provided. ELEMENT t: Preserve Vegetation/Mark Clearing Limits D 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. o 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 cyclon¢ construction f¢nc¢ BMP Ct03 will be installed at the parimat¢r of the construction site. BMP will be installed as first step of construction. BMP C233, Silt Fenc¢ will also be used to mark th¢ north and east down slope p¢rim¢t¢r of the construction site including the access road. BMP to b¢ monitor¢d daily and r¢paired as n¢eded. ELEMENT 2: Esfablish Construction Access D 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 BM Ps, to minimize tracking onto roads. D Locate wheel wash or fire baths on site, if the stabilized construction entrance is not effective in preventing tracking sediment onto roads. ❑ If sediment is tracked off site, clean the affected roadway thoroughly at the end of each tley. 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. o Contl uct street washing only after setlimant 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. Tha construction entrance will b¢ limited to one location from the alley on the south side of th¢ proj¢ct with BMP Ct OT (Construction Entrance.) Version Date: October 7, 20t9 Previous Version Data: February 20, 20t9 Any dirt or mud that is tracked onto the roadway will b¢ clean immedfat¢ly. To ba installed prior to construction. BMP to be monitored daily and repaired as needed. ELEMENT 3: Control Flow Rates O 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 stormwatar runoff From the project site. ❑ Whara necessary to comply with the bullet above, construct stormwatar retention or detention facilities as one of the first slaps in grading. Assure that detention facilities function properly before constructing site improvement (e.g. impervious surtacas). ❑ If permanent infiltration ponds are used for flow control tluring construction, protect these facilities from siltation during the construction phase. A silt fence BMP C233 is to be installed on the north and east bou ntlary along S2^^ Stre¢f and along R Avenue. Th¢ majority of the sit¢ will be disturbed. A temporary sediment trap will be located in the northeast corner of th¢ site. ELEMENT 4: Install Sediment Controls ❑ Design, install, antl maintain affective erosion controls and sediment controls to minimize the discharge of pollutants. O Construct sediment control BMPs (sadimant ponds, traps, filters, etc.) as one of the first steps in grading. These BM Ps shall be functional befo ra other land disturbing activities take place. ❑ Minimize sadimant discharges from the site. The dasig n, installation and maintenance of erosion antl sediment controls must address factors such as the amount, frequency, intensity antl duration of precipitation, the nature of resulting stormwatar runoff, and soil characteristics, including Tha range of soil particle sizes expected to be present on the site. O Direct stormwatar runoff from disturbatl areas through a sadimant 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 dischargetl without a sediment removal BMP, but must meet fha flow control performance standard in Element #3, bullet #t. ❑ Locate BM Ps intendeO to trap sediment on-ska in a manner to avoid interterence with the movement of juvenile salmonids attempting to enter off -channel areas or tlrainages. O Provide and maintain natural buffers around surface waters, direct stormwatar to vegetated areas to increase sediment removal, and maximize stormwatar infiltration. ❑ Where feasible, tlasign outlet structures that withdraw impoundetl stormwatar from the surtace to avoid discharging satliment that is still suspended lower in the water column. Per BMP C233 a silt fence will be installed as not¢d in element 3. To ba installed prior to the start of construction. BMP to ba monito red daily and repaired as n¢¢dad. BMP Cf 62 Scheduling. ELEMENT 6: Stabilize Soils ❑ Stabilize exposed and unworkatl soils by application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seatling, sodding, mulching, plastic covering, erosion control fabrics and matting, soil application of polyacrylamide (PAM), the early application of gravel base early on areas to ba paved, antl dust control. ❑ Control stormwatar volume and velocity within the site to minimize soil erosion. o Control stormwatar discharges, including both peak flow rates antl total stormwatar volume, to minimize erosion at outlets antl 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. During the dry season (May t —Sept 30): 7 days Version Data: October 7, 2Ot9 Previous Version Data: February 20, 20'I9 o During the wet season (Oct t —Apr 30): 2 days ❑ Stabilize soils at the end of the shift before a holiday or weekend if neetletl 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 unwork¢d soils by application of effective BMPs that prevent erosion. Appl{ca ble BMPs includ¢, but ar¢ not limited to: temporary and permanent s¢eding, sodding, mulching and plastic covering. Install plastic covering per BMP Ct23 on Sofls Stockpiles. BMP to b¢ monitored daily and repair¢d as naetl¢d. Refer to Tables 4.t.t in MR #2_ 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 into rceptor dikes, pipes, and/or swales. Off -site stormwatar should ba managed separately from stormwatar generated on the site. ❑ At the top of slopes. collect drainage in pipe slop drains or protected. chann¢Is to prevent erosion. o 'Tam porery pipe slope drains must handle the peak volumetric flow rate calculated using a t O- minute time step from a Type tA, t O-year, 24-hour freq uancy storm for the developed condition. Altemakively, the t O-year, t-Four flow rate predictatl/indicated by an approvetl continuous runoff model, increased by a factor of t.6, may be usetl. The hydrologic analysis must use the existing lantl 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 shoultl be modeled as "lantlscaped" area. o Where t5-minute time slaps era available in an approved continuous runoff model, they may be usetl 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. ❑ Consitlar 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 distu rbad soils. Ex: Vse both mulching and straw erosion control blankets. The sit¢ is flat with a 4.5q slope and slop¢ protection wlil not b¢ an issue. ELEMENT'1: Protect Drain Inlets ❑ Protect all storm drain inlets made operable during construction so that stormwatar 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 sadimeni has filled ono -third of the available storage (unless a different standard is spaciflad by the product manufacturer). ❑ Where possible, protect all existing storm drain inlets so that stormwatar runoff does not enter the conveyance system without first being filteretl or treated to remove sediment. ❑ Keap all approach roads clean. Do not allow sediment and street wash water to enter storm drains Version Date: October 7, 20t9 Previous Version Data: February 20, 20T 9 without prior antl adequate treatment unless treatment is provided before the storm drain discharges to waters of the State. ❑ Inlets should be inspected weekly at a minimum antl daily during storm events. Par detail 1-40.20-00 Storm Orain Inlet prot¢ction d¢vic¢s will b¢ installed at ¢xisting catch basins in the immediate vicinity of the project. To be installed prior to th¢ start of any construction. Two catch basins era located at the northeast corner of the sit¢ along with new catch basins propos¢ at the alley. ELEMENT 8: Stabilize Channels antl Outlets ❑ Design, construct, antl stabilize all on -site conveyance channels to prevent erosion from the following expected peak flows: o �Chann¢Is must handle same peak volumetric flow rate as temporary pipe slope drains list¢d in Element 6, above. ❑ Provide stabilization, including armoring malarial, adequate to prevent erosion of outlets, atljacent stream banks, slopes., antl downstream reaches at the outlets of all conveyance systems. ❑ The best mathotl 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 antl to slow the flow of water. No stormwatar runoff will ba convey¢d off site via cha noels, swales, or streams. ELEMENT 9: Control Pollutants ❑ Design, install, implement, antl maintain affective pollution prevention measures to minimize the discharge of pollutants. ❑ Handle and dispose of all pollutants, including waste materials antl tlemolition debris that occur on -site in a manner that does not cause contamination of stormwate r. ❑ Provitle 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 'I '1 O % of the volume contained in the largest tank within the containment structure. Double -walled tanks do not require additional secondary contain mant. ❑ Conduct maintenance, fueling. and repair of heavy equipment and vehicles using spill prevention and control measures. Clean contaminated surfaces immediately following any spill incident. ❑ Discharge wheel wash or lire 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 lire bath wastewater should not include wastewater from concrete washout areas. ❑ Apply fertilizers and pesticides in a manner and at application retes that will not result in loss of chemical to stormwatar runoff. Follow manufacturers' label requirements for application rates and procedures. ❑ Use BMPs to prevent contamination of stormwatar 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, exposatl aggregate processes, tlewatering concrete vaults, concrete pumping, and mixer washout waters. Adjust the pH of stormwatar if necessary to prevent violations of the water quaiky standards. ❑ Assure that washout of concrete trucks is pertormed off -site or in designated concrete washout areas only. Do not wash out concrete trucks polo the grountl, or into storm drains, open ditches, streets, or streams. Do not dump excess concrete on site, except in destg nested concrete washout areas. Concrete spillage or concrete discharge to surtace waters of the States is prohibited. Do not use upland land applications for discharging wastewater from concrete washout areas. ❑ Obtain written approval from Ecology and provide to the Gity before using chemical treatment other than CO2 or tlry ice to adjust pH. Version Data: October 7, 20'19 Previous Version Date: February 20, 20'19 O Woody debris may ba chopped and spread on site. ❑ Conduc[ oil changes, hydraulic system drain down, solvent and da-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. P¢r BMP Ct54 a Concrete Washout Area is to be installed onsite to capture contaminatatl water from concrete was houffi. To be installed prior to foundation /concrete installation. BMP to ba monitored daily and repair¢d as needed. Contractor is to provide spill prevention Kits for ¢zcavation and concreffi Draws are required on Site. ELEMENT t0: Control De -Watering ❑ Discharge foundation, vault, and trench dewatedng 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. D Discharge clean, non -Turbid da-watering water, such as well -point ground water, to systems tributary to, or directly into su rtace waters of the State, as specified in Eiament 8, provided th¢ 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 "surace waters of the State" may exist on a construction site as well as off site; for example, a creek running through a site. O Handle highly turbid or contaminated dewataring water separately from stonnwater. ❑ Other treatment or disposal options may include: t . I nflkration 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 -sit¢ chamic:al 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. O 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 n¢ed¢d all discharge will b¢ directetl to a temp. sad. trap BMP C240 prior to discharg¢ to the city storm drainage syst¢m. The sedim¢nt trap will be designed for a typical f f,000 sf imp¢rvious area or D.25 acres where the developed 2 year flow is 0.05 cfs X 2080 sf/cfc flow = �04 sf surtac¢ area plan or f0'xt 0'sq uare surface pond area minimum. ELEMENT ��; Maintain BM Ps ❑ Maintain and repair all temporary and permanent erosion and sediment control BM Ps as needed to assure continued pertormance 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 BM Ps are no longer needed. Soma 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 BM Ps installed for the permanent control of stormwatar 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 retu road to the conditions specifietl in the construction Version Date: October 7, 2019 Previous Version Date: February 20, 20t 9 documents. ❑ Remove or stabilize trapped sediment on site. Permanently stabilize disturbed soil resulting from removal of BMPS or vegetation. BMP to be monito red 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 t2: Manage the Project —Projects subject to Minimum Requirements 'I-9 must have a Certified Erosion and Sediment Control Laad (CESCL) for site inspections. Projects subject to Minimum Raq uirements 'I-5 do not require the inspector to be certified. By the initiakion of construction, the SWPPP must identify the CESCL or inspectoq who shall ba present on -site or on -call aT all times. ❑ Phase development projects to the maximum degree practicable antl take into account seasonal work limits to prevent soil erosion and prevent transporting sediment from the site during construction. ❑ Inspection and monitoring —Inspect, maintain, and repair all BMPS as needed to assure contin uetl performance of their intended function. ❑ Maintain, update, antl implement the SWPPP. ❑ Clearing antl gratling activities for developments shall be permitted only if conducted using an approved site development plan (e.g., subdivision approval). ❑ From Oct 'I through Apr 30, clearing, grading, antl 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: t. Sites conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters. 2. Limit activities and the extent of tlisturbad areas. 3. Proposed erosion and sediment control measures. Weather conditions can influent¢ the seasonal limitation on site tlisturbanca. The City of Anacortes has the authority to take enforcement action per AMC 19.76 Stormwater. ❑ The following activities are exempt from the seasonal clearing and grading limitations: i. Routine maintenance antl necessary repair of erosion and sediment control BMPS; 2. Routine maintenance of public facilities or existing utility structures that tlo 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 approvetl 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 73: 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 _ 5-20-202'I_ Applicant Signature Date Version Date: October 7, 20'19 Previous Version Date: February 20, 20t9 TAB 3 iMIN IMUM REQUIREMENT #3) t-2.5.3 Minimum Requirement #3 — Source Control of Pollution All known, available antl reasonable source control BMP's must ba applied to all projects. Source control BMP's must be selected, designed, maintainatl according to the reference Ecology Manual. The intent of source control BMP's is to prevent stormwatar from coming in contact with pollutants. They era acost-effective means of reducing pollutants in stormwata r, and, therefore, should be considered in all projects. All Commercial Properties. Industrial Properties, and Multi -Family Properties, Boatyards, Santl antl Gravel Mining Operations are requiretl to comply wkh this Minimum Requirement. Refer to Chapter IV-2.t Applicable (Mandatory) Operational Source Control BMP's Volume 4: Appendix IV -A: Urban Land Uses and Pollutant Generating Sources. Multi - Family Residences: Oescri ption: Multifamily residential buildings such as apartments and condominiums. The activities of concern are vehicle parKing, vehicle washing and oil changing, minor repairs, and tam porary 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. • S4'1'1 BMPs for Landscaping and Lawn Vegetation Management. • S42f BMPs for ParKing and Storage of Vehicles and Equipment. During construction of th¢ site will b¢ open and subject to ¢rosion. BA�'s as described in the erosion control plan and SWPPP must be constructed at the sourc¢ to limit erosion and sediment laden runoff. The primary sourc¢ for erosion is the driving path Eor the transportation of material to and from th¢ site. A construction entrant¢ from th¢ alley and gravel construction route will limit erosion and silt laded storm water. B1VII' 5411 Landscaping and Lawn/Vegetation blanagem¢nt will be utilized to limit Source pollution_ See BA4P S411 at the end of this report. Version Date: October 7, 2029 Previous Version Data: February 2q 2019 TAB 4 (MINIMUM REQUIREMENT #4) Mlnlmum Requirement #4 —Preservation of Natural Drainage Systems and Outfalls Natural drainage patterns shall be maintained and discharges from the project shall occur at th¢ natural location, to maximum eMent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to dowrtstraam receiving waters and down gradient properties. All outfalls require energy dissipation. The objective is to preserve and utilize drainage systems to the fullest eMant because of the multiple stormwatar benefits Thasa 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. Wili this project disturb the Natural Drainage System or Outfall of the project Site? NO. If yes, refer to section 1.2.5.4 for Supplemental Guidelines for additional information. No change in drainage is proposed for this sit¢. Version Date: October 7, 20t9 Previous Version Oata: February 20, 20t9 TAB 5 (MINIMVM REQUIREMENT #5) • Minimum Requirement #5 — On-s lta Stormwater Management Project thresholds that trigger Minimum Requirements #t through #5, shall utilize the On -site Stonnwatar Management BMP's from List #t for all su rtacas within each type of surtaca in List #t; or, Demonstrate compliance with the LID Pertormance Standard. Projects selecting this option cannot use Rain Gardens. They may choose to use Bioretantion BM P's as described in Chapter V-7 —Infiltration and Bioratention Treatment Facilities to achieve the LID Performance Standard. R¢f¢r to this section of the reference Manual for all Faas)b///tv or /nfaas/b!/ltv Grltaria for List #1 and List #2. Is this project Flow Control ExemptT V¢s (Sea Appendix /-E: Flow Contra/ -Exempt Surfaces Watesrj. If yes, provide reasoning from the applicability section of t-2.5.7 Minimum Requirement #7: Flow Control). If No, then the project triggers Minimum Requirement #7 (t-2.5.7) and possibly Minimum Requirement #8 (t-2.5.8). The city Aas complet¢d additional study for the downstream drainage capacity for basin F4 and determine that the capacity is available which would make this site flow control exam pt. All sites are r¢quired to utiliz¢ BMP T5.13 —Post Construction Soil Quality and D¢pth. If the project is Flow Control Exempt, select from the list below (Skip List t and List 2). BMP T5.13 Post Construction Soils Quality and D¢oth o BMP TS.tOA: Downspout Full Infiltration, or; o BMP TS.t OB Downspout Dispersion Systems, or; BMP TS.t OC: Perforated Stub -out Connections. or: o BMP TS.t t Concentrated Flow Dispersion, or; o BMP TS.t2 Sheet Flow Dispersion BMP TS.t OA: Downspout Full Infiltration: The site is tig ht to the prop¢rty lines and parking lots. Infiltration s¢tbaeks would not meat minimum requirements. BMP T5.tOB Downspout Dispersion Systems: Downspout dispersion requires a flow path of 50 feet or more and that is not feaai ble on this site. BMP T5.t OC: Pertorated Stub -out Connections: This is feasibl¢ and will be id¢ntiflad on th¢ sit¢ plan for each building. BMP TS.t t Concentrated Flow Dispersion: Requires a flow path of 50 f¢et that is not feasible on this sit¢. BMP TS.t2 Sheet Flow Dispersion: The dispersion area of 25 fa¢t below a die parsion trench is not feasible. Version Date: October 7, 20t9 Previous Version Date: February 20, 20t9 The on site parKing surtace will discharge to a bioretention cell or Swale with an underd rain in the northeast corner of th¢ site. Dale Herrigsfad 5-20-20Z I Applioant Si�aature IJaie Version Date: October 7, 20t 9 Previous Version Date: February 20, 20'19 BMP T5.'13e Post -Construction Soil Quality and Uapih Purpose and Oefinitian Naturally occurring �(undtstufbed) soil and vegetation provide impor4 nt stormwa[er func- tionsinclutlin9: waterinfiltratio n;.n utrien[, sediment, and pollutant atlsorption; sediment and pollutant biofiltration; Ovate YintrFlow storage antl transmission: and pollutant decom- position. These functions are largely lost when development strips away native soil and vegetation and replaces-itwitRminimal topsoil and sod. Not only are these important sto rmwater fun�ions lost, buYsuch landscapes themselves become pollution generating pervious surfacestlue to increased use of pesticitles, fertilizers-antl other to ndsca ping and household/industrial chemicals, the concentration of petwastes, and pollut:ritsahat accompany roatlside litter. Est bushing soil quality and depth regains greate rstormwaterfunctions in the post devel- opment landscape. provides increased treatmentof pollutants and sediments that result from development and habitation, and minimizes the need for same landscaping chem- icals.thus retl ucing pollution through prevention. App{ications and Limitations Establishing a minimum soil quality and depth is not the sameas Preservation of nat- urally occurring soEl antl vegetation.IWoweveq establishing. a minimum soil quality and depth will provide improved on -site management of atormwater flow antl water quality. Soli organic matter can be attainetl through numerous materials suoh as co mposC, com- postetl woody material, biosolitls, and forest protluct residuals. It is important that the materials usetl to meet tM1e soil qual ITy and tlepth BMP be appropriate and beneficial to the pia nt co ver to be established. Likewise, i[ is important that Imported topsoils improve soil conditions and do nothave an excessive percent of clay Flnes. This BMP can be considered infea Bible -on till soil slopes greater than 33 percent. Design Guidelines Soil retention. Retfn, in an undisturbed st te, the duff layer and native to psotl to the maximum extent practicable. In any areas requiring gradingremove and stod<- pile the duTTlayer 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 subjecE Lo clearing antl grading that have not bean covered try impervious surFace, lncgiPpra[ed into a drainage tcllityorengineeredasstruc- [ural fill or slopeshall, at project completion, demonstrate 4he following: 1 - A topsoil layer with a minimum organlcmatter content of'10 %dry weight in .planting beds, and 54'o crga nic matter content i h turt areas, and a pW 'from 6.0 2014 Starmwater Management Manua/ fnr Wastem Washington Vo/ume V - Ch aptar 5 -Page 9 9O Version Date: October 7, 20t9 Previous Version Date: February 20, 20'19 to 8.0 or matching the pH ofthe undi5tu rbad soil. Tha top�il lay er shall have a minimum depth of eight inches ¢xcept where tree roots limit the depth of incorpamtion of amendments needed to meet the cite ria_ Subsoils below the topsoil layer should be scarifietl at least 4 inches with some into rpora[ioh of the upper material to avoid stratified layers, where feasible. 2. Mulch planting beds with 2 inches of organic material 3. Us¢ compost and other materials that meet these organic content regdirc- ments a. The organic Conte n[ for"pre-approved" amendment rates can be met only using compost meeting thecompostspacincation for 6MP T7.30- Bi orete noon Cells. Swales and Pla nter Boxes .959 ,with the excep- tion that the compost tnay have up to 35% biosolids or manure. The compost must also have an ofganic matter content of AO%to 65%, and a carbon to nitrogen ra}io below 25:7. The carbon to nitrogen ratio may be as high as 35�t for pla nthgs com- posed entirely of plants native to the PugeTSountl Lowlands region.. b.. Galcul atad amend merit rates may be met through use of composted material.meeting (a.) above; or other orga Nc materials amended to meet the carbon to nitrogen ratio requirements, and no[ exceeding the contaminant limits ides ntified in Tables 220-B., Testing Parameters, in WAC t 73-350-`L2g. The resulting sail should be conducive Lb the type of vegeation to be established. Impl ementatlon Options: Tha soil quality design guidelines listed above can be met by using one ofihemetirods listed below: t. Leave undisturbed native vegetation and still, and protect from compaction during constructidn. 2. Amend existinH site topsoil or subsoil either at defacflt'pre-approved rates, or abcusrom calcul atetl rates based on tests of [he soil and amendment. 3. Stockpile existing topsoil tlurtng grading, and replace it prior to planting. Stockpiled topsoil must also be amended if needed to meet the organic mat - tenor tlepth requirements, either at a default "prey ppmved' rate or eta cus- tom calculated rate. 4, Importtopsoil mix of su�cie nt organic content and depth to meet the require- ments. 20>4 Sformwater Management Manua/.fnr Wastam Washington Volume V - Ch aptar 5-Pages 912 Version Date: October 7, 20t9 Previous Version Dat¢: February 20, 20'19 More than ane mathotl maybe usetl oh diffe rertt portions of Che se me site.. Soil that already meets the depth antl organic matter quality standards,. antl isnot com- pacted, does not neetl to be amandetl_ P{anWing/Psrmifting//nspecfianNari{icatlon Guidelines 8 Procedures Local governments are encouraged to adopt gWdeCines and procetlures simLar to those recommendetl in Guidelines and Resources For Implementing Soil Quality antl Depth BMP T5.13 in WDOE Stormwater Management Manual for Western \A/ashingFon_ This document is available at:. http:f/wwwaoii sforsalmon-orglpdflSoll :BMP Manual Dtlf Mairttanance Establish soil -quality and depth towartl the end ofconstruction antl onceestab- fishetl,:protecNfrom compaction, suchas from large-machineryuse, and from erosion. PlanT vegetation anal mulch the amendetl soil area after installation. Leave plans tle bns or its equivale ni onahe soil surface:to replenish organic matter. Retluce antl adJust, where possible, the use of -irrigation; Tertilfaers, herbicides and pesticides, ratherthan continuing to .implement fo••r'merly ester blishetl practices, RunoS Model Representation A reas meeting the deslgn,guitlelines may be entered into approved m�off �models.as "Pasture" rather than "Lawn." Flow reduction cratlits can be taken in runoff motlaling when BMP TBa 3: Post-Ggn- struc9on Soil Quality andDepth is used as part ofa dispersion design untlar-the con- tlitions describetl in: BMP TSa OB' Downspout Dispersion Svste ms (p 905) BMP T5.11 : Concentrated Flow Dispersion (p g05) BMP T5:12: Sheet Flow Dispersion (p:9081 BMP T5.18: Reve ree Slooa Sidewalks (p.93'�) BMP T5.30: Full Dispersion (0.9391 (for public roatl projects) 2014 Sfomnwarer Management Manua/3oi'Wastam Washfnginn Volume V - Chaptar5 -Page 9'13 Version Date: October 7, 2019 Previous Version Date: February 20, 20'19 Fig ��¢ Y-5.3.3 P.IanYing bad Croys-Sackion I e.�am. � -._. � L � �/ IX/ M9TT0 SCAt'E Figure V-5.3.3 Paanting Bed Cross -Section Re..�.e ���,.a.Y x+s 2094 Starmwater Management Manual for Wastam Washington Volume V -Chapter 5 -Page 914 Version Date: October 7, 20'19 Previous Version Date: February 20, 20'19 F ignre V-�,4.96 Typical Bio retention wlV ndertlra in JI o-m+in�ama�a m w L � i sMw..w a�,- �\i � o. � � � i �E ih � T —� �`_ 1 Y "°"p M. _ �� � � � <�> saa e s .'.'spa. �v�a �bn, a rne�ea.r..wm Ndea: SmMYwbDroa0e 3"mm.0 z. e�•, �vasx o.. wsrwn Norroscn�c Figure V 3.4.1 b e� e Typicai Bioretention wN.nderd rain a � e.�.•nzo.e ECOLOGY �.�+m-.+.�+.�..a-r:..e,ez»�.,mw+:.rc,..ir...x,rr�om �a��,..�wwnq nm.,.ma�a�.. smm��o� - 20 R4 Stormwater Man agament Manua/'for Western Washington Volume V - :Chapter l - Paga 9fi2 Version Date: October ], 20'19 Previous Version Date: February 20, 20'19 B B — [M INUMUM REQUIREMENT 6 -RUNOFF TREATMENT) Rafar to t.2.5.6 and provide th¢ r¢quiretl information for this Minimum Requirement. Threshold requirements for detcrmiaing the applicabiliTy of tuuofi treatment. Projects in which the toffiI of pollution -generating hard surface (PGHS) is 5,000 square Feet or more in a threshold discharge area of the project, or Projects in which the toffiI of pollution-g¢n erative pervious surfaces (PGPS)-oot including permeable pavements -is three-quarters (3/4) of ao acre or more io a threshold discharge area, and from which there wffi be a surface discharge is a natural or man-made conveyance system from the site. The total Pollution -generating hartl surface Is propose to be t,995 square feet of paved driveway and t ,908 pav¢tl ally for a total of 3,903 sf of PGHS and under the S,OOO square f¢et threshold r¢quiring treatment. The overall site is '14,999 square feet of 0.34 acr¢s and under the 0.75 acre threshold. Runoff Treatm¢nt is not required but we propose including a 65 lineal foot bio-Filtration swat¢ along the north boundary of the site to the east and dischar9 in9 to the city storm system_ Tha swala will treat the drlvaway runoff area of t,995 square feet. The alley will discharge directly to the enclosed drainage s Ystem. Version Date: OMober 7, 20t 9 Previous Version Data: February 20, 20'19 TAB 7 — <MINUMUM REQUIREMENT 7 —FLOW CONTROL) Refer to 7.2.5.7 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 discharg¢ ar¢a� or Projects that convert'/. acres or more of vegetation to lawn or Iandscape� or convert 2_S acres or more of native vegetation to pasture in a threshold dis-charge area, and from which th¢re is a surfac¢ discharge in a natural or man-made conveyance syat¢m from the site, or Projects that through a com bivatiov of effective hard surfaces and converted vegetation areas cause a O.10 cubic feet per second increase iv th¢ lOD-year flow frequency from a threshold discharge area as estimated using the Weat¢ry Washington Hydrology Model or other approved model and one -hour time steps (or a O.35 cfs increase using 15-minute tim¢ steps). Tha total proposetl new or replaced impervious hard surfaces is t2,427 square feet and above the t 0,000 square feet threshold discharge area. As discussed above the downstream drainage system has capacity for the full build out of Shis site. Flow Control is not required. Version Date: October 7, 20t9 Previous Version Date: February 20. 2Ot9 TAB 8 — <MINUMUM REQUIREMENT S —WETLAND PROTECTION) Refer to 'I .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 t.2.5.9 and provide the required information for this Minimum Requirement. Cnnctr�vcaan Grtaria Tho bio£dtratiov swaleshotdd ndt be pva into oporation until areas of exposed soil io the contributing drainage catdhmont have bean sufiiciarRly stabilized. Deposition of eroded soils can impede the growth ogress in fire swa]e and xaduca swale4eatmem citictivcneas, Thvs, eiTeotivc and sediment control measures should tc.nain in place until thc ewala tregaratiov is esrablishatl (see Volume ]I for o.nsion and sudimnnt oontrol J3Lvlps). Avoid compaction during c nstruction. Orade biofiltars ip.attain. uniform longitudinal and katoral slopes Moixtenrsnre Giterio latspaee bioEltars ai least once every G mamths, pre£crably dur'vtg storm events, and alxo: after storm events oF> (l.i inch minfaI.V 24 hours. Maintain adaquam gross growth and eliminate bare spots. Mow gresses,.if Handed for good growth {typically maintain at 4 — 9 inches and not below design flow level (KingCounty, 1.99%j). Remove sediment as.needad at hand of the Swale i£grass gtovmh is ivhlbitad in greater then lOpercent of Ute swa7e, or ifffie sediment is blocking thc distribution .and entry aftlta water Ylting County, 1998). - Aemove leaves, litter, and oily materials, and re -aced or resod, snd ragrade, as needed. Clean curb cuts and Icve] spmadars as needed. Prevont scouring end soil erosion in thc bio£lter. liflow c}wnncling occurs, regrade and reseed the biof'alter, as necessary. Maintain access to biohiter inlot, outlet, and to mowing (Figure 9.87 lfa Swale is equipped with undardrains, vehicular trafiioon the Swale Bottom (other than grass mowing aquipmonf:) should be avoided m prevent damage xo the drainpipes. APPENOI% 1 —Survey performed by a Professional Land Surveyor im3a�olwiu�.�xn��r��enrrum�suen�n zm�m�zx: s..._ ...... .�,. =tt, _ j � ,� � �� �1 � , ---a � pp3 �SI� gg� � rt. I ��� ru ,� � _ _� ., 4 a � �x�v�_ vR as'AVENUE'M @ � A d `S3 �m, g; 333366 F3 pq g g& -tea g�\. @ 6 � �vE g� # "$��56` �� fi�i�Ej*`+���'�. R9'E�6n��Ma � iG+1 9 � c 3a��=��T $d� ae4[ � � R D `d' paw # ��s �� P C. APPENDIX 2 —Soils Anayls is (Volume 1, Chapter 3.t .'I) Sons Report a=f°`:µ Linda Spicher, Septic System Designer License 5700294 ' � (360)708-3004 rre.zwy�R Project/Client Landed Gantry Homes 8. Communities Paga / of Contact: Steve Baugbn Property Owner: Jennings Revocable Living Trust Site Address: 806 33r° Street, Anacortes, WA Parcel Number: 605Z5 !late on Site: 5/1 L2020 Map Unit, Natural Resources Conservation Service: ri20 - Bow -Urban land complex, O to 8 % slopes Hytl rologic Sbil Group: G!D Soil Tvoar Loading Rate A —6 gravel, imparted 'I 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" ��--'© O — 6 gravel, imported � 1.0 5 — 16 dark brown fine santly loam 4 0.6 16 — 22 tan sandy clay loam, rooks, mottles 6 03 72 —.36 tan loamy clay, mottles 7 nat suitatila anticipatatl water table at 16" � Ona-of aevan numariwi Gassificationsof fine germ particles antl mck fragments as tlescritretl in WAC ?From Chapter 24�-2T2A WAC: 'Hydraulic Loading Rat®" means SM1e amount of effluent applied to a q)ven treatrnent atop. In SINS cM1apter axprassetl as gallons per squarc Too[ per tlay (9aVsq. tt./day). ��i� � GF � gg ., ` _ g � ffi C m g �� gTp •1 '�' rOv..sv c � ���� _ �� e��� = `e og�� - _ _ � m�s� e o s�8� ���� ���g 4 �. �� o �. ..�,� - - ;� .z ,� .- f __ ,�_ =� �= ` �,� �, A 0 r � «s,:� T __ c � � � � . s version vaxe: �c�ooar i,. �u-ia rrevious version Saxe: reoruary emu, w'�a --tee.. �®..,.,_ P"�a' � gyp^ �64+s[_. S9e„l LANOBGME __ LANpBGAPE PLAN ^, m _ w,... _ _ ,wrN ua aaa� �� RI=% � m � 'I 1 raux OF �qq �I Version Date: October �, 20'19 Previous Version Date: February 2D, 2019 sm� MaP-,skaa� ��..�,.�a. w.a„ree� W M 4 h Version Date: October 7, 20t9 Previous Version Date: February 20, 20t9 y�rss S or S Skagit C:ovnty Ar®a• Wasitinyton 2l)—Bow-Urban land oomplax� O to B percent elopes Mao Unit Settin • Natrona/map unit symbo/: 2hy1 • E/evation: O to 450 feet • Mean annua/ precipitarlon: ZO Yo fi0 Inches • Mcian annua! air temperature: 48 to 50 degrees F • Frost->•ree:peNod: 150 to 220 days Farmland dtass:fcacion: Not prime fermlantl � �� •Mao Unit Composition • .E' • .Bow and Simi/ar soils: 60 percent _ • Urban /and: 35 percent • Minor components: 5 percent •awEs -w.1o� Estimates are based on observatlons� descriptions, and transec[s of the mapun)[. Descriotion of Bow Setting • Landfbrrn: Terraces, higslopes Parent mai'erla/: Volcadic ash, gladolawstrine deposits, and glaual drill Typical proFile • Hl -Ora 9lncha5: gravelly ashy 102m • H2 - > to Z> inUes: very gravelly ashy loam • H3 - 1> to 31 inches: day loam H4 - 31 ['0 60 inches: silty clay PLoparties and qualities • Sfope: O to 8 percent • Oepth to restrlRiye feafure: MoreCM1an 80 inches • Nature/ dra/Wage class: Somewhat poorly tlrained • Capacity of the most !!m/Hng layer tp transmit water (Ksat): Moderately low To moderately high (0.06 to 0.2D in/br) • Depth to water tab/e: About 6 to 18 ruches Frequency of flooding: None • Frequency of ponding,' None Available water sto age !n AroA/e: High (about 10.4 inches) •Interpretive groups • Land capability c/assificatlon (]rrigated): None spedFled • Land capabrOty daSsiflCetion (Wan! /gatCd): 4w • Hydro/pg/c Soil G/vup: C✓� • Forage s✓@abl/!ty group: Seasonally We[ SOIIs (Gp02XN2o2WA) Hydrlc So// rating: Yes •Description of Vrban Land Interpretive groups • Land capability class/ftaztipn (irrigated): None specified • .Land capab)l/ty class/Acatlon (nonirrigaLed): 8 Hydricsoil rating: No •.Minor Components B@Ilingham, untlrainetl • Percent of map un/t: 5 percent . Landlonp: pePresslons • -HydNc soil raMngs Yes Version Date: October 7, 20'19 Previous Version Date: February 20, 20'19 APPENDIX 3 —Modal Soii Management Plan for BMP T5.�3 An alternate document acceptable to the City of Anacortas is a Tast Report provided by the Soils Supplier that identifies the soils to ba 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 era not sure who the supplier will be at the time of building permit application. For projects that trigger Minimum Raq uiremants 'I through 5, the Tast Report will be provided to the Building Department. Projects triggering Minimum Requirements 'I through 9, the Test Report will be provitletl to the Engineering Department. DEFERRED SUBMITTAL: PROVIDE A TEST REPORT FROM SOILS SUPPLIER TO THE BUILDING DEPT. Version Date: Octob¢r 7, 20'19 Previous Version Date: February 20, 20'19 PRO.TF.Ci INFORMATION "Model Soil Management Plan for BMP T5.13" age#ofpaga Cmm�Mte all information n a l a only cite nddk_cs and narmif n mbrr ran adAihinnai n Site Addreea /Lot No.: 38P4 N Avavuc Derma Permit Number. Permit HOId¢r: Phon¢: Mnuing Aaar¢aa� Contact P¢rson: Phon¢: Plan Pr¢ ar¢d B AREA # (shovTd match Are¢ # on Stte Plan) PLANTING TYPE Tmf _ UndisNrbed native veg¢tation _ Planting Beds _Other: SQUARE. FOOTAGE OF TIHS AREA: square feet SCARIFICATION _ mciies (depth) of acariRcation nead¢d to achiev¢ Emished total 12" loosened depth. _ Subsoil will be acariRed P1iE-APPROVLrD nches of compost or imported topsoil applied AMENDMENT METHOD: X 3.,i (com.eraFoaj cxor, inches to cubic ya+-dr) PRODUCT: _ Topsoil import — u. yazds per 1,000 aq. R. _ Amend with compost X ,000s sq.R. in this area _ Stockpile and amend = cubic yartls of amrndmem —» QUANTITY: CU. YDS. ds. stock ilad eeded [o cover thts are¢ to desF rated de ih CUSTOM AMENDMENT ARach tea[ results and ralcuiations. i'opsoil import inches organic matter or topsoil import PRODUCT: _ _ Topsoil 8e compost liR X 31 Amend = cu. yards / 1,000 s4� R. _ _ Stockpile and amend X ,DOOs sq.R. in this area � cu. yds. stockpiled) =cubic yards of amendm¢nt —� —� —+ —� QUANTTTY: CU. YDS. MULCH ,000 sq.R. PRODUCT: X ¢�2 (conversion, eo gtve d tnch mulch depth) = cubic yards of mulch --� —s —+ —� —a —� QUANTITY: CU. YDS. Date: Inspector: ApprovM: R¢visiona Required: Date: Iuspector: Approved: R.evisiptts Required: Version Date: October 7, 20'19 Previous Version Date: February 20, 20'19 APPENDIX 4 —Determining Construction Sit¢ Sediment Damage Pot¢ntial (Appendix '� — NPDES Phase II Permit) Notes: See attached. All projects within the City of Anacortes are requiretl to complete that document under Appendix 4. Weslern Ti'nshington Phase II Stormwater Permxt 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-spaciflc features which indicate that the site must be inspected prior to clearing and construction. Any alternative evaluation process must be documental and provide for aq uivalant environmental review. Step one is to determine if there is a sedim¢nVerosion 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 sedimenVerosion sensitive feature and it is hydraulically near the site than go to step throe to determine the construction site sediment transport potential. Sediment erosion sensitive features are areas subject to significant degradation du¢ to the effect of sediment deposition or erosion. Special protection must be provided to protect them. SadimanVerosion sensitive features include but era not lira fled 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; iii. Category 1, II, and 111 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 sadimenVerosion sensitive features, and proceed To step two. If there are none the assessment is complete. Sites are hydraulically near a feature if the pollutant load and peak quantity of runoff firm the site will not be naturally attenuatetl before entering Fha feature. Tha conditions that render a site hydraulically near to a feature include, but are not limited to, the following: - i. Tha feature or a buffer to protect the feature is within 200 feat downstream of the site. ii. Runoff from the sHe is tight -lined to the feature or flows to the feature through a channel or ditch. August �, 20f 3, Modifrad January 96, 2015 Appendfx 7- Oatarmining Sediment �amaga Potential Pages f of3 Version Date: October 7, 20t9 Previous Version Date: February 20, 20t9 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. Shoat flow through a vegetated area with dense ground cov¢r v. Flow through a wetland not included as a sensitive feature vi. Flow through a significant shallow or adv¢rse slope, not in a conveyanc¢ channel, between the site and the sensitive feature. Itlentity any of the sediment/erosion sensitive features from step one that are hydraulically near the sit¢, and proceed to step three. If none of the sediment/erosion sensitive features are hydraulically near the sit¢, The ass¢ssment is complete. Using the worksheat below, datermin¢ the total points for each tlavalopment site. Assign points based on the most critical condition that affects 'I O % or more of the site. If soil testing has been performetl on site, the results should be used to determine the p r¢dominant soil type on fhe site. Otherwise, soil information should be obtainetl from the county soil survey to determine Hydrologic Soil Group (Table of Engineering Index Properties for step 'I.D) antl Erosion Potential (Table of Water Features for step 'I.E) When using the county soil survey, the dominant soil type may be in question, particularly when the site falls on a bou ntlary 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 taste 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 Transoort Rating <� 00 Low ❑'100 High A high transport raking indicat¢s a higher risk that the site will generate sediment contaminated runoff. Construction Site Sediment Transport Potential WorKsheat A. E 's' I ri n Points 2% or less .. O >5-t 0 %.......................................................................................... t 5 B. Site Area to be cleared and/or graded: <5.000 s9. ft...................................................................................... O 5.000 sq. ft. — 1 acre ................................................... .................... 30 >t acres......._.._.............._..._.__..........__..................................... 50 C. Quantity of cut and/or FII on site: <500 cubic Yards............................................................................... O 500 — 5,000 cubic Yards_...__.__._ ................___...................... _. _._. 5 >5,000—'I O,000 cubic Yards........._......_..._ .............._......_.......... '10 >'I O,000 — 20,000 cubic yards ........................................................ 25 >20.000 cubic yards....................................................................... 40 D. Runoff otential of redominant II sours o rvi Hydrologic soilgroup A ..................... _.........................._ ___................... _........ O Hydrologic soil group B.._.__.............._................. _........ _..........._. 'I O HYdrologic soil 9rouP C................................................................. 20 HYdrologic soil 9rouP D................................................................. 40 E. Erosion Potential of predominant soils (Unifred Classification Svsteml: GW, GP, SW, SPsoils............................................................................................. O Dual classifications (GW-G M, GP-G M, GW-GC, GP-GQ SW-S M, SW -SC, SPSM, SP-SC)..................._...... 70 GM. GC, SM. SC soils......__...............__.................._................... 20 ML. CL. MH, CH soils_............_............_...................................... 40 F. Surface or Groundwater entering site id entifiad and intercaotadt: Yes_........_._..__..........__-__-____...__....._................................._.. O No.................................................................................... ................ 25 G. Depth of cut or heig ht of fill >t0 fe¢Y. Yes...._.........._.........__.........._ .................. _.._......_......._..........__ 25 No.............................................................................................................0 A. learin an rn Yes 50 No_._._ ................................................. ......_..........0 TOTAL POINTS. � If no surface or groundwater enters site, give O points. APPENDIX 5 —Sit¢ Plan witF all applicabl¢ information (Minimum Size 'I'1 x'17 at a legible scale) SEE FULL SIZE ECS PLAN APPENDIX 6 — Documentetl Site Photos (Show all directions of the site, inclutling frontage) Location: 32id 8 R Avenue Description of the photo: Sit¢ from Alley and R Avenu¢ Photo to Ran by: Oale HerrigsWd, 5-20-202t } � a-�� M- � I � I � 1 J �4 { ' . � I _�' �. i_ �_x.�*s.�� APPENDIX 7 —Drainage BMP Facility Maintenance Covenant Note: To ba recorded prior to: 'I) Temporary Certificate of Occupancy; 2) Final Certificate of Occupancy, antl or; 3) Final Acceptance of the project. This is Covenant is req uiretl for any Pannanant Stormwater Facility constructed on a project site. Tha applicant shoultl work with the the City of Anacortes Engineering Department on formalizing the document for recording.