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Home My WebLink AboutPermit File BLD-2018-0302 1602 Latitude Circle (3) gLD-- 2_6tc - 4?)6 z-or o� 1pO2- L 1l" ' L Al.( PLANNING,COMMUNITY,&ECONOMIC DEVELOPMENT DEPARTMENT ® ..Y ®� M hang Address:PO Box 547,Mnacortes,WA 93221 J Phone:360.299.B 984,Pax: 360.293.l 938 C®RNCAMT c aC4Q t®tea N*o Na c IgN@dda g Stormwater requirements are(used on the 2012 Stormwater Dilaraagemo it Manual for Western Washington (SVNNIMWW).A link is provided on the City of Aoacor os website,under Planning Department,Stormwater Regulations,as well as under the Engineering Division of Public Works. Residential construction is exempt from additional stormwater provisions if it involves no expansion of hard surfaces,no use beyond that previously misting,and results in no significant adverse hydrological impact. Building permit applications for lots that are part of a subdivision that was recorded no more than 10 years prior to the date of the complete building permit application may continue to use the stormwater codes in effect at the time the subdivision application was submitted, if storrnwater was addressed at the subdivision/plat level. if construction has ne started as of January 1,2022,the site will be subject to the 2012/2014 manual, If your project adds less them 2,000 sq.ft.of new plus replaced hard surface area,MD which disturbs less than 7,000 square feet .ff land,you must consider all 13 Elements of the Constauctiin Stormwater Pi llution Plan(SWPPP). Fill out the SWPPP Checklist and explain how the elements are considered,or describe how site conditions render the element unnecessary and the exemption fr•ma that element is clearly justified. You will not need to continue with this document. If your project adds 2,000 sq, ft.or more of new plus replaced hard surface area,OR which disturbs 7,000 sq.ft.or more of land-Minimum Requirements I-5 of the SVIRMWW apply,and you can continue with this document. If adding 5,000 sq.ft.or more of new hard surfaces/OR converting 32,670 sq.ft.or more of vegetation to lawn or landscaped area/OR converting 108,900 sq.ft.or more of native vegetation to pasture Minimum Requirements 1-9,eff the SWh9IL apply.If Minimum requirements 1-9 apply, please see the Large Scale Stormwater Plan Checklist for additional submittal requirements. Owner€gerne: 48.t IPA .y site ddress: 6'( 2 //") Brief Description of the Project: r r vi MI1U2019 Pre Deve6 . d Conditir•Jns Ru;;::fi if the Site: �c �i 6 Y OF ANACOM+=(` Page 1 of 4 tO? March 22,2017 ' �� ©mdmlopwd Conditions iA Runoff of the Side: Summarize difficult site paraaiotens,the natural drainnage 2ys nm,and drains aga to and from Kitimat properties, including i ypass ff0orss: 0 hydrological Site flan:Collect and analyze information on existing conditions to aid in determining low impact development feasibility o which locations are most appropriate to evaporate,transpire,and infiltrate, with the following information: o Survey by land Survey r, Engineer,or other qualified pralessionaih Show existing public and private development, utility infrastructure,hydrological features(seeps, springs,closed depression areas,drainage swages,streams, wetlands,and water body survey and classification report showing wetland and buffer boundaries),flood hazard areas,geological hazards, buffers,aquifer and wellhead protection areas,topographic features that may act as natural stormwater storage,infiltration,or conveyance. Include the natural receiving waters that stormwater runoff will either directly or eventually discharge.Show topography,display acreage and outlines of all drainage basins;existing stormwater drainage to and from the site; routes to existing, construction,and future flows at all discharge points;and the length of travel from the farthest upstream end of a proposed storm drainage system to any proposed flow control and treatment facility. Identify areas of potential erosion problems Show contours as follows: • Up to 10%slopes=2 ft. contours • Over 10%to less than 20%slopes=5 ft.contours • 20%or greater slopes= 10 ft. contours • [Elevations at 25 ft. intervals o Soils deport:Done by a soil scientist certified by Soil Science Society of America, licensed sewage designer,or other suitably trained persons working under the supervision of a professional engineer,geologist, hydrologist,or any other professional supervised by an engineering geologist registered in Washington State.(Soils Report Page 2 of 4 March 22,2017 must include details as listed on Pg.79).In addition,describe soils by name,erodibiiity, settleability,permeability,depth,texture,and soil structure. Testing should occur between December 1 and April 1. o Sons Map:Based on the report. o Preliminary Development Site Plan Layout:Locate proposed buildings,roads,parking lots,landscaping features,on-site stormwater management BMPS(Determine BMPs starting on Pg.95.Suggested BMPs correlate with responses to the 13 elements f the SWPPP,Pg.237,and preliminary location of stormwater treatment and retention/detention facilities.Considerations are on Pg.83.These methods could reduce required facility sizes,but are not required for approval.Show existing and proposed contours,show all cut and fill slopes indicating top and bottom of slope catch lines,and identify developed condition drainage basins. o Survey of existing native-vegetation cover:This is only required if there are native soil and vegetation protection areas proposed for the site.Survey shall be done by a licensed architect,arborist,qualified biologist or project proponent identifying any forest areas on the site and a plan to protect those areas.The preserved area should be placed in a separate tract or protected through recorded easements for individual lots. o Vicinity Map:Clearly locate the property,identify all roads bordering the site,show the route of stormwater off-site to the local natural receiving water,and show significant geographic features and sensitive/critical areas(streams,wetlands,lakes,steep slopes, etc). 0 Construction Stormwater Pollution Prevention Plan(SWPPP)—The SWPPP shall be implemented beginning with initial land disturbance and until final stabilization.From October 1 through April 30,clearing,grading,and other soil disturbing activities shall only be permitted if shown that silt-laden runoff will be prevented from leaving the site through methods listed on pg.44. Best Management Practices(BMPs)Standards and Specifications are listed on pg.261. Please see pg.230 for details on using the Site Analysis to produce the following materials: o Narrative:Explain and justify the pollution prevention decisions made.This will contain concise information concerning existing site conditions,construction schedules, wet season construction activity,constraints,and other pertinent items that are not contained on the drawings.This is based on the 13 Construction Elements,which must be considered unless site conditions render the element unnecessary and the exemption is clearly justified. Elements listed on.pg.44&described in detail starting on pg.236. o Drawings&Notes:Where and when the BMPs should be installed,the performance the BMPs are expected to achieve,and actions that will be taken if the performance goals are not achieved.Show water quality monitoring locations. o Special Reports&Studies:Include any studies(i.e.wetlands delineation).If a facility is required and feasible for Minimum Requirement 5,a PIT Test must be done in the location that the facility location is proposed based on the preliminary development site plan layout. ❑ Other permits:Any other necessary permits as required by other regulatory agencies.Identify if those permits include conditions that affect the drainage plan,or contain more restrictive drainage-related requirements. Prior to Final Stormwater Inspecti0n ❑ Permanent Stormwater Control Plan Drawing:Select BMPs based on the Preliminary Development Site Plan Layout from the Site Analysis Summary. Provide a scale drawing of the Page 3 of 4 March 22, 2017 lot(s)and any public ROW that display the location of On-Site RMPs and the areas sewed by them.These documents will be recorded and attached to a declaration of covenant and grant of easement associated with each lot that includes On-site BMPs, Provide design details,figures, and maintenance instruction for each [RMP. Provide a written summary of how it complies with the applicable requirements. Mar to Final Oscupanto 0 Operation Et Maintenance ftt nwah include a manual for each ffkw control and treatment facility,including any distributed bioretentlon facilities that are used to help meet flow control and/or treatment requirements.The manuai shall include a description of the facility,what it does,and how it works. it must also identify and describe the maintenance task,and the frequency of each task.The task and frequencies must meet the standards of the SWMMMMWW. include a maintenance activity log that will indicate what actions will have been taken and where it should be kept and made available for inspection by the City. ❑ Declaration of Covenant for Privately Maintained How Control Treatment Facilities and On- Site ©FRI UV Management Q Pso Any flow control& treatment facilities and On-Site Stormwater management RMPs for which the applicant identifies operation Af maintenance to be the responsibility of a private party must have a declaration of covenant and grant of easement.After City approval,the declaration of covenant and grant of easement must be signed and recorded. Design details,figures,and maintenance instructions for any[MP shall be attached.A map showing the location of newly planted and retained trees claimed as flow reduction credits shall also be attached. ❑ Record Doeareentso Record total impervious sur,ace area of the site and their locations with the county auditor. By signing belrrw,y..ui are certifying that y4 tr have read and understand the stornwater requirements. we sure that you have checked off all applicable boxes. 05/7/10/, Applican Signature Da/ / Page 4 of 4 March 22, 2017 EXHIBIT "A" 1602 LATITUDE CIRCLE LOT 18, PLAT OF 48 NORTH P133676 Responses to the "Complete Residential Stormwater Plan Checklist—Minimum Requirements 1-5". Brief Description of the Project: To construct one Single-Family Residence (SFR) on a single legal lot within the City of Anacortes. The existing property is Lot 18, Plat of 48 North, is 7,781 square feet in size, and Zoned as R2. Pre Developed Conditions & Runoff on the Site: The property is vacant.The site slopes from the southeast to the northwest at a grade of approximately 17%. The property is bounded as follows: NORTH: Lot 19, 48 North. EAST: Fully improved street of Latitude Circle. South: Lot 17, 48 North. West: P133694 Developed Conditions & Runoff of The Site: The proposed improvements are as follows: Construct a SFR with an approximate lot coverage of 30.6%, and an impervious lot coverage of 43.5%. No detention was required for the Plat of 48 North, but there is an existing water quality bio-swale for the plat. Roof drains and footing drains will be hard lined to the existing stormwater collection system. The point of connection for Lot 18 is located in the northwest corner of the lot. After construction, landscaping will be provided to permanently stabilize the site from erosion. Summarize difficult site parameters, the natural drainage system, and drainage to and from adjacent properties, including bypass flows: The site slopes from the southeast to the northwest at a grade 17% and the disturbed soil has been seeded and/or mulched to reduce erosion. The only significant tributary drainage the lot may receive is from Lot 18 and 19. Lots 19 and 19 will have their own drainage self-contained so as not to impact Lot 18 and intercept drains will be installed to adequately eliminate impacts as needed. Hydrological Site Plan: Survey: A topographic survey has been performed by Herrigstad Engineering, showing the existing improvements around and within the subject property, along with the existing contours at 2-foot intervals. Soils Report: A Geologic Hazard Assessment and Geotechnical Engineering Services report was prepared by GeoEngineers, dated July, 21, 2015, and is already part of the record documents provided to the City of Anacortes. Preliminary Development Site Plan Layout: An "Erosion Control &Site Plan" has been prepared by Landed Gentry Development, Inc., showing both the existing and proposed improvements as requested. See attached. A "Survey of existing native vegetation cover" was performed by the Urban Forestry Services, Inc., for the project, dated August 12, 2015, and a tree preservation plan was developed and adopted by the City of Anacortes. A "Vicinity Map" has been provided on Sheet 2 of 2 of the "Erosion Control & Site Plan", attached. Construction Stormwater Pollution Prevention Plan (SWPPP): See attached. Other Permits: Building Permit for SFR. 7 0 Phoning, CComrunpf, p E©onomoo Development Departmeng PC Box 547, Qng©©t o, WA 982 1 r PH: 360.29R191 Qoogoimic ©H s o we p PdikaMiR Frog®Roil Mi7u4 Please check oft boxes to show that each element has been road and understood. Provide details where applicable and if certain aspects are unnecessary or Q:3c mpt, clearly gustihyo Details of the 13 Elements and the correlating 136ViPs are listed on pg. DO of the 22018 Storrmwater Management nt Manual for Western Washington( WRINWW).A lines is provided on the City of Anecortes VdObsite,under planning, Community,VA Economic Development Department,as well as under Stormwater on the Engineering Division of Publics Work's rage. ep ©weer Name: 0i4/iii Ant A C cr21 r L Site Address: / 0 2- L A �//•C CLJ Prepared By: / ." F !,?a'_` C ;A Ira( ' , f %aP, A ,1 r /fT, The St;•rmwater checklist or building permit determined that: ❑ The 13 elements must be addressed for ❑ These elements must be addressed for construction activity adding under 2,000 construction activity adding 2,000 sq.ft. sq.ft.of hard surface area. or more iff hard surface area. This means that an attached narrative and site plan are required with this document Under each element eisol;I the be , ,ana ernent r radices ESMPs used car-Usti 9 reasonln forth*so that will not E3 sedo 0f needed a lease attach a narvathre t®VunGner explain flans or ldstufieati no �� x.t/&r Pn2 74c cP /3 E,•/TS EIS t 'E T la 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. ❑ Retain the duff layer, native top soil,and natural vegetation in an undisturbed state to the maximum degree practical. Page 1 of a larch, 2017 [ d NEED 2 Establish Const em aion Access ❑ Limit construction vehicle access and enit to one route, if possible. ❑ StaNHee access points with a pad of queen/spells,crushed mck,or other equivalent eatiPs,to ((�U ini rmixe"tracking onto roads. ❑ d©Cate wheel Wash or tire baths on site, if the stebiliee d construction entrance is not effective in preventing tracking sediment Ma roads. ❑ if sediment is tracked off site, clean the affected roadway thoroughly et 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 oiler sediment is removed in accordance with the above bullet. ❑ Control street wash wastewater by pumping ping back on site or©the.iise preventing It from discharging into systems tributary to waters of the State. E�f li[ 3o Control Flow Rates ❑ Protect properties and waterways diwnstresm of development sites from erosion and the asscociated 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 ab:?ve,construct story water retention or detention facilities as one of the first steps in grading. ssure that detention facilities function properly before constructing site improvement(e.g. impervis us surfaces). ❑ If permanent infiltration ponds are used for flow control during construction,protect these facilities from siltation during the construction phase. ELE I T 4: Install Sedin ent 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 star water runoff,and soil characteristics, including the range of soil particle sizes expected to be present on the site. ❑ s>irect stormwater runoff from disturbed areas through a sediment pond or other appropriate sediment removal f :,FP, before the runoff leaves a construction site or before discharge to an Page 2 of 8 March, 2017 infiltration facili,y.Runoff from My stabilized areas may be discharged vAthoat a sediment removal [ IIP,but must meet the flow control performance standard in[Element V3,bulOet no O Locate RMPs untended to trap sedllrn M 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 surfece waters,direct stormwater to vegetated areas to increase sediment removal,and mm imize stormwater infiltration. O Where feasible,design outlet structures that withdraw impounded storralavdater from the surface to avoid discharging sediment that is still suspended lower in the water column. ELEMENT 5o Stabilize Soils ❑ Stabilize m posed and unworked soils by application of effective DMPs that prevent erosion. Applicable RMPs include,but are not limited to:temporary and permanent seeding,sodding, ulching, 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. O 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 unworhed for more than the time periods set forth below to prevent erosion. o During the dry season(May 1 ®Sept 30): 7 days o During the wet season(Oct 1—Apr 30):2 days ❑ 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. ELE. Protect Slopes 0 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). Page 3 of 8 March, 2017 0 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 c''Tcemporowy pipe slope drains must handle the peak volumetric flow rate calculated using a 10-minute time stop 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 106,may be med.The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributa rry areas outside the project limits. For tributary areas on the project site, the analysis Mg use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. Of using the Western Washingt•n Hydrology Model (WW 3M)to predict flows, bare soil areas should be modeled as "landscaped'area. o Where 15-minute time steps are available in an approved c ntinnous 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. OoLE ENT 7: Protect Drain Inlets O 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. O 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 without prior and adequate treatment unless treatment is provided before the storm drain discharges to waters of the State. ❑ Inlets should be inspected weekly at a minimum and daily during storm events. Page 4 of g March,2017 ELEIZr'JE6`T 3:Stabilize Channels and Outlets ❑ Design,construct,and stabilise all on-site conveyance channels to prevent erosion from the following eapected peak flows: o ''Channels must handle same peak volumetric flow rate as temporae/pipe dope drains listed in Element 6,above. ❑ Provide stabilimation,including armoring material,adequate to prevent evasion off outlets, adjacent stye ambaniks,dopes,and downstream reaches at the outlets of all conveyance systems. ❑ The best method for stabilising 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. ELEiMN7 9:Control pollutants ❑ Design, install, implement,and maintain effective pollution prevention measures to minimize the discharge of pollutants. ❑ 6Kandle 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. O Provide cover,containment,and protection from vandalism; ffc r 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 110%of the volume contained in the largest tank within the containment structure. Double-walled tanks do not require additional secondary containment. ❑ Conduct maintenance,fueling,and repair of heavy equipment and vehicles using spill prevention and control measures.Clean contaminated surfaces immediately following any spill incident. O 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. ❑ 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. Page S of 8 March, 2017 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.D§ not dump recess concrete on site,m cept 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 Ciw before using chemical treatment other than CO2 or dry ice to adjust pH. ❑ Woody debris may be chopped and spread on site. ❑ Conduct oil changes,hydraulic system drain down,solvent and de-greasing cleaning operations, fuel tnd 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 foil wing any discharge or spill incident. Emergency repairs may be performed vnmsite using temporary plastic placed beneath and, if raining,over the vehicle. GELEE v ENT Sri:: Contrrsl De-Watering ❑ 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 8,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 dean 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. O Handle highly turbid or contaminated dewatering water separately from stormwater. ❑ 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. O 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 Page 6of8 March,2017 of water quality standards for turbidity. The easiest way to avoid discharging muddy water is through infiltration and preserving vegetation. ELEMENT A.1a Maintain I MPs ❑ Maintain and repair all temporary and permanent erosion and sediment control 0 iPs as needed to assure continued performance of their intended function in accordance with BMP specifications. ❑ Remove all tempt vary erosion and sediment control IBMPs within 30 days after achieving final site stabilization c•r after the temporary bMPs are it. huger needed.Some temporary erosion and sediment control C MPs are bio-degradable and designed to remain in place following construction such as compost socks. 0 provide protection to all viPs installed for the permanent control of stormwater from sediment and compaction.All[MPs that are t, remain in place following completion of ccnstrucctiou shall be examined and placed in full operating conditions. If sediment enters the C3MPs during construction, it shall be removed and the facility shall be returned to the conditions specified in the construction documents. ❑ Remove or stabilize trapped sediment on site. Permanently stabilize disturbed soil resulting from rem,ival of:MPs or vegetation. 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 tin es. Management details starting on Pg.256. ❑ 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. ❑ Inspection and monitoring v inspect,maintain,and repair all a MPs as needed to assure continued performance of their intended function. ❑ Maintain, update,and implement the SWPPP. ❑ Clearing and grading activities for developments shall be permitted only if conducted using an approved site development plan(e.g.,subdivision approval). ❑ From `act 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: Page 7 of 8 March,2017 1. Site conditions including existing vegetative coverage,slope,soil type,and proximity to receNing 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 Cif of Anacortes has the authority to take enforcement action per AMC 19.7E Storrs water. ❑ The following activities are exempt fro- the seasonal clearing and grading limitations: 1. Routine maintenance and necessary repair of erosion and sediment control[3MP ; 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 Creator runoff within the site in approved and installed erosion and sediment control facilities. ELEMENT 132 Protect Low lmpoct Dov opment AMPS ❑ if implementing any hioretentioo facilities or Pain gardens,see!'r:; for requirements. `157/2 7/00/? ApplicSIt Signature . Da / Page 8 of 8 March, 2017 EXHIBIT "B" 1602 LATITUDE CIRCLE LOT 18, PLAT OF 48 NORTH P133676 Responses to the "13 Elements of SWPPP" (Construction Stormwater Pollution Prevention Plan) ELEMENT 1: Preserve Vegetation/Mark Clearing Limits The clearing limits will be marked by using either BMP C233: Silt Fence, or BMP C103: High Visibility Plastic or Metal Fence, as shown on the Erosion Control Plan. C233 is to be used along the west and north property lines and the C103 along the east and south property lines. Preservation of the native top soil will be preserved as much as is practical by use of a stock pile as shown on the Erosion Control Plan. Stock pile location may vary. Stock pile shall be protected as indicated on the Erosion Control Plan. ELEMENT 2: Establish Construction Access BMP C105 shall be used as the construction access. Only one access point is proposed. No wheel wash is proposed. Any track out shall be cleaned daily by shoveling and/or sweeping. More frequent cleaning as necessary. ELEMENT 3: Control Flow Rates No flow rate controls are designed for the individual lot. However, erosion control BMPs described in ELEMENT 4, below will reduce velocity of flows. ELEMENT 4: Install Sediment Controls The following BMPs are proposed as temporary sediment controls: C103: High Visibility Plastic or Metal Fence To be place along the perimeter of the site to mark the clearing limits for the construction crew and to alert the public as to the potential dangers of the ongoing onsite construction activity. C233:Silt Fence To be place along the perimeter of the site to protect downstream properties from the transport of coarse sediment, as well as to mark the clearing limits for the construction crew and to alert the public as to the potential dangers of the ongoing onsite construction activity. C105: Stabilized Construction Entrance To be place in the location of the future driveway off of Latitude Circle, to provide a stable and clean point of access for construction vehicles. C121: Mulching To provide immediate temporary protection of exposed soil from erosion, as well as conserving moisture. C123: Plastic Covering Primarily used to protect the stock pile from erosion. May be used as a short term cover of small areas of exposed soil. Not intended for large areas. C140: Dust Control As this project will be constructed during the dry season, dust control may be necessary to protect the surrounding neighborhood. The primary source of dust control will be by spraying of the disturbed area with water. C220: Storm Drain Inlet Protection Onsite inlet protection will use Block&Gravel Curb Inlet Protection. Offsite inlet protection will use Catch Basin Filters manufactured for use at construction sites. C207: Check Dams Where drainage swale are created to convey stormwater, temporary gravel check dams may be used to reduce velocity and to dissipate flow energy. The following BMP improvement(s) are proposed for permanent sediment controls: C124: Sodding Sodding is to establish permanent turf for immediate erosion protection. C125:Top Soiling Provides a suitable growth medium for final site stabilization with vegetation. T5.13: Post-Construction Soil Quality and Depth Establishes soil quality and depth regains greater stormwater functions in the post development landscape, provides increased treatment of pollutants and sediments that result from development and habitation. ELEMENT 5: Soil Stabilization The following are temporary soil stabilization BMPs: C233: Silt Fence To be place along the perimeter of the site to protect downstream properties from the transport of coarse sediment, as well as to mark the clearing limits for the construction crew and to alert the public as to the potential dangers of the ongoing onsite construction activity. C105: Stabilized Construction Entrance To be place in the location of the future driveway on Latitude Circle,to provide a stable and clean point of access for construction vehicles. C121: Mulching To provide immediate temporary protection of exposed soil from erosion, as well as conserving moisture. C123: Plastic Covering Primarily used to protect the stock pile from erosion. May be used as a short term cover of small areas of exposed soil. Not intended for large areas. C140: Dust Control As this project will be constructed during the dry season, dust control may be necessary to protect the surrounding neighborhood. The primary source of dust control will be controlled spraying of the disturbed area with water. C220: Storm Drain Inlet Protection Onsite inlet protection will use Block& Gravel Curb Inlet Protection. Offsite inlet protection will use Catch Basin Filters manufactured for use at construction sites. C207: Check Dams Where drainage swale are created to convey stormwater,temporary gravel check dams may be used to reduce velocity and to dissipate flow energy. The following are permanent soil stabilization BMPs: C124: Sodding Establishes permanent turf for immediate erosion protection. C125:Top Soiling Provides a suitable growth medium for final site stabilization with vegetation. T5.13: Post-Construction Soil Quality and Depth Establishes soil quality and depth regains greater stormwater functions in the post development landscape, provides increased treatment of pollutants and sediments that result from development and habitation. ELEMENT 6: Protect Slopes C235:Straw Wattles Straw Wattles reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sediment. ELEMENT 7: Protect Drain Inlets C220: Storm Drain Inlet Protection Onsite inlet protection will use Block&Gravel Curb Inlet Protection. Offsite inlet protection will use Catch Basin Filters manufactured for use at construction sites. ELEMENT 8: Stabilize Channels and Outlets C207: Check Dams Where drainage swale are created to convey stormwater,temporary gravel check dams may be used to reduce velocity and to dissipate flow energy. ELEMENT 9: Control Pollutants All fuel, lubricants, paint, and/or other hazardous material shall be stored in a lockable, covered storage container if kept on site. ELEMENT 10: Control De-Watering While excavating to install the sanitary sewer, stormdrain, and water systems to depths up to 14 feet, no ground water was encountered. Therefore, no dewatering is anticipated. However, should dewatering become necessary, it should be pumped and dispersed to a well vegetated area within the project site. ELEMENT 11: Maintain BMPs A trained Certified Erosion and Sedimentation Control Lead (CESCL) will be on the job site. CESCL personnel are trained in and responsible for the proper maintenance of the erosion control BMPs. The CESCL will work with the City of Anacortes Inspector to maintain all BMPs. ELEMENT 12: Manage the Project A trained Certified Erosion and Sedimentation Control Lead (CESCL)will be on the job site. CESCL personnel are trained in and responsible for the proper maintenance of the erosion control BMPs. The CESCL will work with the City of Anacortes Inspector to maintain all BMPs. ELEMENT 13: Protect Low Impact Development BMPs No low impact development BMPs are planned or required for this individual lot. EXHIBIT"C" 1602 LATITUDE CIRCLE LOT 18, PLAT OF 48 NORTH P133676 PRIMARY BMPs damage from burying and smothering. . Vegetative buffer zones for streams, lakes or other waterways shall be established by the local permitting authority or other state or federal permits or approvals. Maintenance Standards Inspect the area frequently to make sure flagging remains in place and the area remains undisturbed. Replace all damaged flagging immediately. BMP C103: High Visibility Fence Purpose Fencing is intended to: 1. Restrict clearing to approved limits. 2. Prevent disturbance of sensitive areas, their buffers, and other areas required to be left undisturbed. 3. Limit construction traffic to designated construction entrances, exits, or internal roads. 4. Protect areas where marking with survey tape may not provide adequate pro- tection. Conditions of Use To establish clearing limits plastic, fabric, or metal fence may be used: • At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. . As necessary to control vehicle access to and on the site. Design and Installation Specifications High visibility plastic fence shall be composed of a high-density polyethylene material and shall be at least four feet in height. Posts for the fencing shall be steel or wood and placed every 6 feet on center(maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sag- ging between posts. The fence color shall be high visibility orange. The fence tensile strength shall be 360 lbs./ft. using the ASTM D4595 testing method. If appropriate install fabric silt fence in accordance with BMP C233: Silt Fence (p.367)to act as high visibility fence. Silt fence shall be at least 3 feet high and must be highly vis- ible to meet the requirements of this BMP. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 269 Metal fences shall be designed and installed according to the manufacturer's spe- cifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. Maintenance Standards If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. BMP C105: Stabilized Construction Entrance / Exit Purpose Stabilized Construction entrances are established to reduce the amount of sediment transported onto paved roads by vehicles or equipment. This is done by constructing a stabilized pad of quarry spalls at entrances and exits for construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be entering or leaving a construction site if paved roads or other paved areas are within 1,000 feet of the site. For residential construction provide stabilized construction entrances for each residence, rather than only at the main subdivision entrance. Stabilized surfaces shall be of suf- ficient length/width to provide vehicle access/parking, based on lot size/configuration. On large commercial, highway, and road projects, the designer should include enough extra materials in the contract to allow for additional stabilized entrances not shown in the initial Construction SWPPP. It is difficult to determine exactly where access to these projects will take place; additional materials will enable the contractor to install them where needed. Design and Installation Specifications See Figure II-4.1.1 Stabilized Construction Entrance (p.273)for details. Note: the 100' minimum length of the entrance shall be reduced to the maximum practicable size when the size or configuration of the site does not allow the full length (100'). Construct stabilized construction entrances with a 12-inch thick pad of 4-inch to 8-inch quarry spalls, a 4-inch course of asphalt treated base (ATB), or use existing pavement. Do not use crushed concrete, cement, or calcium chloride for construction entrance sta- bilization because these products raise pH levels in stormwater and concrete discharge to surface waters of the State is prohibited. 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4 -Page 270 Metal fences shall be designed and installed according to the manufacturer's spe- cifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. Maintenance Standards If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. BMP C105: Stabilized Construction Entrance / Exit Purpose Stabilized Construction entrances are established to reduce the amount of sediment transported onto paved roads by vehicles or equipment. This is done by constructing a stabilized pad of quarry spalls at entrances and exits for construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be entering or leaving a construction site if paved roads or other paved areas are within 1,000 feet of the site. For residential construction provide stabilized construction entrances for each residence, rather than only at the main subdivision entrance. Stabilized surfaces shall be of suf- ficient length/width to provide vehicle access/parking, based on lot size/configuration. On large commercial, highway, and road projects, the designer should include enough extra materials in the contract to allow for additional stabilized entrances not shown in the initial Construction SWPPP. It is difficult to determine exactly where access to these projects will take place; additional materials will enable the contractor to install them where needed. Design and Installation Specifications See Figure II-4.1.1 Stabilized Construction Entrance (p.273) for details. Note: the 100' minimum length of the entrance shall be reduced to the maximum practicable size when the size or configuration of the site does not allow the full length (100'). Construct stabilized construction entrances with a 12-inch thick pad of 4-inch to 8-inch quarry spalls, a 4-inch course of asphalt treated base (ATB), or use existing pavement. Do not use crushed concrete, cement, or calcium chloride for construction entrance sta- bilization because these products raise pH levels in stormwater and concrete discharge to surface waters of the State is prohibited. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 270 A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the following standards: Grab Tensile Strength (ASTM D4751) 200 psi min. Grab Tensile Elongation (ASTM D4632) 30% max. Mullen Burst Strength (ASTM D3786-80a)400 psi min. AOS (ASTM D4751) 20-45 (U.S. standard sieve size) . Consider early installation of the first lift of asphalt in areas that will paved; this can be used as a stabilized entrance. Also consider the installation of excess concrete as a stabilized entrance. During large concrete pours, excess concrete is often available for this purpose. • Fencing (see BMP C103: High Visibility Fence (p.269)) shall be installed as neces- sary to restrict traffic to the construction entrance. • Whenever possible, the entrance shall be constructed on a firm, compacted sub- grade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. . Construction entrances should avoid crossing existing sidewalks and back of walk drains if at all possible. If a construction entrance must cross a sidewalk or back of walk drain, the full length of the sidewalk and back of walk drain must be covered and protected from sediment leaving the site. Maintenance Standards Quarry spalls shall be added if the pad is no longer in accordance with the spe- cifications. . If the entrance is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include replacement/cleaning of the existing quarry spalls, street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash. . Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or sta- bilized on site. The pavement shall not be cleaned by washing down the street, except when high efficiency sweeping is ineffective and there is a threat to public safety. If it is necessary to wash the streets, the construction of a small sump to con- tain the wash water shall be considered. The sediment would then be washed into the sump where it can be controlled. . Perform street sweeping by hand or with a high efficiency sweeper. Do not use a non-high efficiency mechanical sweeper because this creates dust and throws soils into storm systems or conveyance ditches. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 271 . Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed immediately. . If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing (see BMP C103) shall be installed to control traffic. . Upon project completion and site stabilization, all construction accesses intended as permanent access for maintenance shall be permanently stabilized. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 272 G�c )JuAlf7 a urc)t c—.)(9J R)]©qrio[Ti 'Entrance e NOT TO SCALE ®ekd /ICI MO. k'Z*4" • i:• 1.0 I•i1Iz. grzlirsidiriptiviriN le ti ter-a`t-�`t-��►'X-�`X- .// 1 .,i i I. I i ♦ 1.4 � •�--��s.� •. 100' min. Install driveway 41!"< dP � i4P4 culvert if there is a �1 — �' roadside ditch present f l' i' 4" - 8" quarry �i YTA," IN!",!.�!►. spells ` 11-Forroz% Geotextile iti~eso s�"`� �s�i`� � 'I r l..,:"i."...iIPAL .� ‘ 7- \<, Notes: 15' min. 1. Driveway shall meet 12" minimum thickness the requirements of the permitting agency. 2. It is recommended that Provide full width the entrance be of ingresslegress crowned so that runoff area drains off the pad. FigureQ =4o Stab Hzed Construction Entrance DEPARTMENT OF Revised June 2015 _ECOLOGY Please see http://www.ecy.wa.gov/copyrighthtrrtl for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Stomriwater Management Manual for Western Washington Volume II m Chapter 4 - Page 273 Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C 105: Stab- ilized Construction Entrance/Exit. The products did not pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to con- sideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent.html BMP C106: Wheel Wash Purpose Wheel washes reduce the amount of sediment transported onto paved roads by motor vehicles. Conditions of Use When a stabilized construction entrance (see BMP C 105: Stabilized Construction Entrance/Exit(p.270)) is not preventing sediment from being tracked onto pavement. • Wheel washing is generally an effective BMP when installed with careful attention to topography. For example, a wheel wash can be detrimental if installed at the top of a slope abutting a right-of-way where the water from the dripping truck can run unimpeded into the street. . Pressure washing combined with an adequately sized and surfaced pad with dir- ect drainage to a large 10-foot x 10-foot sump can be very effective. . Discharge wheel wash or tire bath wastewater to a separate on-site treatment sys- tem 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. Design and Installation Specifications Suggested details are shown in Figure II-4.1.2 Wheel Wash (p.276). The Local Per- mitting Authority may allow other designs. A minimum of 6 inches of asphalt treated base (ATB) over crushed base material or 8 inches over a good subgrade is recommended to pave the wheel wash. Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will work well to test clearance. Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck tongues with water. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 274 . BFMs and MBFMs provide good alternatives to blankets in most areas requir- ing vegetation establishment.Advantages over blankets include: • BFM and MBFMs do not require surface preparation. . Helicopters can assist in installing BFM and MBFMs in remote areas. . On slopes steeper than 2.5H:1 V, blanket installers may require ropes and harnesses for safety. . Installing BFM and MBFMs can save at least$1,000 per acre com- pared to blankets. Maintenance Standards Reseed any seeded areas that fail to establish at least 80 percent cover(100 percent cover for areas that receive sheet or concentrated flows). If reseeding is ineffective, use an alternate method such as sodding, mulching, or nets/blankets. If winter weather pre- vents adequate grass growth, this time limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. . Reseed and protect by mulch any areas that experience erosion after achieving adequate cover. Reseed and protect by mulch any eroded area. . Supply seeded areas with adequate moisture, but do not water to the extent that it causes runoff. Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C 120: Tem- porary and Permanent Seeding. The products did not pass through the Technology Assessment Protocol — Ecology (TAPE)process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to con- sideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa.gov/prog rams/wq/stormwater/newtech/eq u ivalent.html. BMP C121: Mulching Purpose Mulching soils provides immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and top- soil in place, and moderating soil temperatures. There is an enormous variety of mulches that can be used. This section discusses only the most common types of mulch. Conditions of Use As a temporary cover measure, mulch should be used: 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4-Page 284 . For less than 30 days on disturbed areas that require cover. . At all times for seeded areas, especially during the wet season and during the hot summer months. . During the wet season on slopes steeper than 3H:1 V with more than 10 feet of ver- tical relief. Mulch may be applied at any time of the year and must be refreshed periodically. . For seeded areas mulch may be made up of 100 percent: cottonseed meal; fibers made of wood, recycled cellulose, hemp, kenaf; compost; or blends of these. Tack- ifier shall be plant-based, such as guar or alpha plantago, or chemical-based such as polyacrylamide or polymers.Any mulch or tackifier product used shall be installed per manufacturer's instructions. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. Design and Installation Specifications For mulch materials, application rates, and specifications, see Table 11-4.1.8 Mulch Standards and Guidelines (p.286). Always use a 2-inch minimum mulch thickness; increase the thickness until the ground is 95% covered (i.e. not visible under the mulch layer). Note: Thickness may be increased for disturbed areas in or near sensitive areas or other areas highly susceptible to erosion. Where the option of"Compost" is selected, it should be a coarse compost that meets the following size gradations when tested in accordance with the U.S. Composting Council "Test Methods for the Examination of Compost and Composting" (TMECC) Test Method 02.02-B. Coarse Compost Minimum Percent passing 3"sieve openings 100% Minimum Percent passing 1" sieve openings 90% Minimum Percent passing %"sieve openings 70% Minimum Percent passing 14'sieve openings 40% Mulch used within the ordinary high-water mark of surface waters should be selected to minimize potential flotation of organic matter. Composted organic materials have higher specific gravities (densities)than straw, wood, or chipped material. Consult Hydraulic Permit Authority (HPA) for mulch mixes if applicable. Maintenance Standards . The thickness of the cover must be maintained. . Any areas that experience erosion shall be remulched and/or protected with a net 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 285 or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remuiched. Table 11-4.1.8 Mulch Standards and Guidelines Mulch Quality Application Remarks Material Standards Rates Cost-effective protection when applied with adequate thickness. Hand-application generally requires greater thickness than blown straw. The thickness of straw may be reduced by half when used in conjunction with seeding. In windy areas Air-dried; 2"-3" thick straw must be held in place by crimping, using a free from 5 bales per tackifier, or covering with netting. Blown straw Straw undesirable 1,000 sf or always has to be held in place with a tackifier as seed and even light winds will blow it away. Straw, how- coarse 2-3 tons per ever, has several deficiencies that should be con- material. acre sidered when selecting mulch materials. It often introduces and/or encourages the propagation of weed species and it has no significant long-term benefits It should also not be used within the ordinary high-water elevation of surface waters (due to flotation). Approx. 25- Shall be applied with hydromulcher. Shall not be No growth 30 lbs per used without seed and tackifier unless the applic- Hydromulch inhibiting 1,000 sf or ation rate is at least doubled. Fibers longer than factors. 1,500 - about 3/4 - 1 inch clog hydromulch equipment. 2,000 lbs per acre Fibers should be kept to less than 3/4 inch. No visible water or More effective control can be obtained by increas- dust during ing thickness to 3". Excellent mulch for protecting handling. 2" thick final grades until landscaping because it can be Must be pro-min.; directly seeded or tilled into soil as an amend- duced per approx. 100 ment. Compost used for mulch has a coarser size Compost WAC 173- tons per gradation than compost used for BMP C125: Top- 350, Solid acre soiling /Composting (p.297) or BMP T5.13: Post- Waste (approx. Construction Soil Quality and Depth (p.911). It is Handling 800 lbs per more stable and practical to use in wet areas and Standards, yard) during rainy weather conditions. Do not use near but may wetlands or near phosphorous impaired water have up to bodies. 35% 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 286 Table 11-4.1.8 Mulch Standards and Guidelines (continued) Mulch Quality Application Material Standards. Rates: Remarks biosolids. Average size shall This is a cost-effective way to dispose of debris be several from clearing and grubbing, and it eliminates the inches. problems associated with burning. Generally, it Chipped Gradations should not be used on slopes above approx. 10% Site eget- from fines 2"thick because of its tendency to be transported by run- ation to 6 inches min.; off. It is not recommended within 200 feet of sur- in length for face waters. If seeding is expected shortly after texture, vari- mulch, the decomposition of the chipped veget- ation, and ation may tie up nutrients important to grass estab- interlocking lishment. properties. No visible water or dust during handling. This material is often called "hog or hogged fuel". Must be pur-2"thick The use of mulch ultimately improves the organic Wood- chased min.; matter in the soil. Special caution is advised based from a sup- approx. 100 regarding the source and composition of wood- Mulch or plier with a tons per based mulches. Its preparation typically does not Solid acre Wood Waste (approx. provide any weed seed control, so evidence of Straw Handling 800 lbs. per residual vegetation in its composition or known Permit or cubic yard) inclusion of weed plants or seeds should be mon- one exempt itored and prevented (or minimized). from solid waste reg- ulations. A blend of Cost-effective protection when applied with loose, long, adequate thickness.A minimum of 95-percent of thin wood the wood strand shall have lengths between 2 Wood pieces and 10-inches, with a width and thickness Strand derived 2" thick min. between 1/16 and 3/8-inches. The mulch shall not Mulch from native contain resin, tannin, or other compounds in conifer or quantities that would be detrimental to plant life. deciduous Sawdust or wood shavings shall not be used as trees with mulch. (WSDOT specification (9-14.4(4)) 2014 Stormwater Management Manual for Western Washington Volume 11-Chapter 4-Page 287 Table 11-4.1.8 Mulch Standards and Guidelines (continued) Mulch Quality Application Material; Standards Rates Remarks high length- to-width ratio. BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets (commonly called matting) are strands of material woven into an open, but high-tensile strength net(for example, coconut fiber matting). Blankets are strands of material that are not tightly woven, but instead form a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets, but cover the ground more completely. Coir(coconut fiber)fabric comes as both nets and blankets. Conditions of Use Erosion control nets and blankets should be used: . To aid permanent vegetated stabilization of slopes 2H:1 V or greater and with more than 10 feet of vertical relief. . For drainage ditches and swales (highly recommended). The application of appro- priate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can cap- ture a great deal of sediment due to their open, porous structure. Nets and blankets can be used to permanently stabilize channels and may provide a cost-effective, environmentally preferable alternative to riprap. 100 percent synthetic blankets manufactured for use in ditches may be easily reused as temporary ditch liners. Disadvantages of blankets include: . Surface preparation required. • On slopes steeper than 2.5H:1 V, blanket installers may need to be roped and har- nessed for safety. . They cost at least$4,000-6,000 per acre installed. Advantages of blankets include: 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 288 Table 11-4.1.8 Mulch Standards and Guidelines (continued) Mulch Quality Application Material Standards Rates Remarks high length- to-width ratio. BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets (commonly called matting) are strands of material woven into an open, but high-tensile strength net(for example, coconut fiber matting). Blankets are strands of material that are not tightly woven, but instead form a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets, but cover the ground more completely. Coir(coconut fiber)fabric comes as both nets and blankets. Conditions of Us- Erosion control nets and blankets should be used: • To aid permanent vegetated stabilization of slopes 2H:1V or greater and with more than 10 feet of vertical relief. • For drainage ditches and swales (highly recommended). The application of appro- priate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can cap- ture a great deal of sediment due to their open, porous structure. Nets and blankets can be used to permanently stabilize channels and may provide a cost-effective, environmentally preferable alternative to riprap. 100 percent synthetic blankets manufactured for use in ditches may be easily reused as temporary ditch liners. Disadvantages of blankets include: • Surface preparation required. ▪ On slopes steeper than 2.5H:1V, blanket installers may need to be roped and har- nessed for safety. • They cost at least$4,000-6,000 per acre installed. Advantages of blankets include: 2014 Stormwater Management Manual for Western Washington Volume II Ch pter 4 -Page 288 . Installation without mobilizing special equipment. . Installation by anyone with minimal training . Installation in stages or phases as the project progresses. • Installers can hand place seed and fertilizer as they progress down the slope. . Installation in any weather. . There are numerous types of blankets that can be designed with various para- meters in mind. Those parameters include: fiber blend, mesh strength, longevity, biodegradability, c.st, and availability. ign and llnstall £takn Spc ca acata©n . See Figure 11-4.1.3 Channel Installation (p.292) and Figure 11-4.1.4 Slope Install- ation (p.293)for typical orientation and installation of blankets used in channels and as slope protection. Note: these are typical only; all blankets must be installed per manufacturer's installation instructions. . Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. . Installation of Blankets on Slopes: 1. Complete final grade and track walk up and down the slope. 2. Install hydromuich with seed and fertilizer. 3. Dig a small trench, approximately 12 inches wide by 6 inches deep along the top of the slope. 4. Install the leading edge of the blanket into the small trench and staple approx- imately every 18 inches. NOTE: Staples are metal, "U"-shaped, and a min- imum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. 5. Roll the blanket slowly down the slope as installer walks backwards. NOTE: The blanket rests against the installer's legs. Staples are installed as the blanket is unrolled. It is critical that the proper staple pattern is used for the blanket being installed. The blanket is not to be allowed to roll down the slope on its own as this stretches the blanket making it impossible to main- tain soil contact. In addition, no one is allowed to walk on the blanket after it is in place. 6. If the blanket is not long enough to cover the entire slope length, the trailing edge of the upper blanket should overlap the leading edge of the lower 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 289 blanket and be stapled. On steeper slopes, this overlap should be installed in a small trench, stapled, and covered with soil. . With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the design engineer consult the manufacturer's information and that a site visit takes place in order to ensure that the product specified is appropriate. Information is also available at the following web sites: 1. WSDOT (Section 3.2.4): http://www.wsdot.wa.gov/N R/rdonlyres/3B41 E087-FA86-4717-932D- D7A8556C CD57/0/ErosionTrainingManual.pdf 2. Texas Transportation.Institute: http://www.txdot.gov/business/doing_business/product evaluation/erosion_ control.htm . Use jute matting in conjunction with mulch (BMP C121: Mulching (p.284)). Excel- sior, woven straw blankets and coir(coconut fiber) blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. . In general, most nets (e.g.,jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. . Extremely steep, unstable, wet, or rocky slopes are often appropriate candidates for use of synthetic blankets, as are riverbanks, beaches and other high-energy environments. If synthetic blankets are used, the soil should be hydromulched first. . 100-percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or fiber mesh and stitching which may last up to a year. . Most netting used with blankets is photodegradable, meaning they break down under sunlight(not UV stabilized). However, this process can take months or years even under bright sun. Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to find non-degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition, birds and small animals can become trapped in the netting. Maintenance Standards . Maintain good contact with the ground. Erosion must not occur beneath the net or blanket. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 290 o Repair and staple any areas of the net or blanket that are damaged or not in close contact with the ground. o Fix and protect eroded areas if erosion occurs due to poorly controlled drain ge. 2014 Stormwater Management Manual for Weste ,; Washington Volume II®Chapter 4 -Page 291 Figure 11-4.1.3 Channel Installation r- ,l. `k NOT TO SCALE WI:"' /\ ** F7 LONGITUDINAL ANCHOR TRENCH TERMINAL SLOPE AND CHANNEL �I ANCHOR TRENCH if 4 4 4 4 r �`` 4 STAKE AT 3=-5' 'I` .iC .t ,,1, c opo r `i=: r g P r dry rr . �� CHECK SLOT AT 25'/NTERVALS U' /� ISOMETRIC VIEW ,ki>.7 1,11 ,i'i .' (àyr P INITIAL CHANNEL ANCHOR TRENCH INTERMITTENT CHECK SLOT Source:Clackamas County 2009 Notes: Erosion Prevention Planning and 1. Check slots to be constructed per manufacturers specifications. Design Manual 2. Staking or stapling layout per manufacturers specifications. 111\11- - - Figure 11-4.1.3 IllWili Channel Installation DEPARTMENT OF Revised June 2015 ECOLOGY Please see http:llwww.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability,and disclaimer. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 292 fJ t LJ.11e® „ci a ° g[1co o f}r-a lbA n 0 iii Anchor in 6"x 6" min. trench and staple at 12"intervals S, -•••1 ., ',=a%,^ i , .• .`fir;: • -- �°e`;:i.i�• •d%�ri _: ..tea. -t Min. 2"overlap - 111`h 111�1111 11-11-, = ,r= 11 11=11=1 rl=if=ti= 11=11=11= Allh II 11=11= !` =11 11 11: ,:LJt: =1f'=11-11`- Min. 6" overlap :•T.:.:?C!'e`i;may. �11- 11=•11— .11= 11 =11=11=L4r-1ti:II-I �' w®• -:'�,` '^it .11r-1 11 L,Mqaf'»,ly�s. rM � �. n = t :_. n="1� Staple overlaps =1=1=f1=11=1111f —fl lf1 li=Mz.I1 11: 111—fa il l-►'12 =t1I= 11-1-- 11=11 1 111It I 1 1 1 max. 5"spacing II1111 11-II�11-.11: 71711.—.11-;i1:i11-:117— .11-1f-1 -- — Bring material down to a level area, turn the end under 4" and staple at 12" intervals Notes: 1, Slope surface shall be smooth before placement for proper soil contact. 2. Stapling pattern as per manufacturer's recommendations. 3, Do not stretch blankets/mattings tight- allow the rolls to mold to any irregularities. 4. For slopes less than 3H:1V, rolls may be placed in horizontal strips. 5. If there is a berm at the top of the slope, anchor upslope of the berm. 6. Lime, fertilize, and seed before installation. Planting of shrubs, trees, etc. should occur after installation. NOT TO SCALE a k.tr /i imili Shope .nstaUatoon Revised June 2015 DEPARTMENT OF EL LOGS Please see http.•llwww.ecy.wa.govlcopyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 S toi'mwater Management Manual for Western Washington Volume II A Chapter 4 - Page 293 BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and dis- turbed areas. Conditions of Use Plastic covering may be used on disturbed areas that require cover measures for less than 30 days, except as stated below. . Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term (greater than six months)applications. . Due to rapid runoff caused by plastic covering, do not use this method upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. • Plastic sheeting may result in increased runoff volumes and velocities, requiring additional on-site measures to counteract the increases. Creating a trough with wattles or other material can convey clean water away from these areas. • To prevent undercutting, trench and backfill rolled plastic covering products. • While plastic is inexpensive to purchase, the added cost of installation, main- tenance, removal, and disposal make this an expensive material, up to $1.50-2.00 per square yard. . Whenever plastic is used to protect slopes install water collection measures at the base of the slope. These measures include plastic-covered berms, channels, and pipes used to covey clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a plastic covered slope with dirty runoff from a project. • Other uses for plastic include: 1. Temporary ditch liner. 2. Pond liner in temporary sediment pond. 3. Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored. 4. Emergency slope protection during heavy rains. , 5. Temporary drainpipe ("elephant trunk") used to direct water. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 294 Design and Installation Specifications . Plastic slope cover must be installed as follows: 1. Run plastic up and down slope, not across slope. 2. Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet. 3. Minimum of 8-inch overlap at seams. 4. On long or wide slopes, or slopes subject to wind, tape all seams. 5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath. 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and tie them together with twine to hold them in place. 7. Inspect plastic for rips, tears, and open seams regularly and repair imme- diately. This prevents high velocity runoff from contacting bare soil which causes extreme erosion. 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. . Plastic sheeting shall have a minimum thickness of 0.06 millimeters. . If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable pro- tection shall be installed at the toe of the slope in order to reduce the velocity of run- off. Maintenance Standards . Torn sheets must be replaced and open seams repaired. . Completely remove and replace the plastic if it begins to deteriorate due to ultra- violet radiation. . Completely remove plastic when no longer needed. . Dispose of old tires used to weight down plastic sheeting appropriately. Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C123: Plastic Covering. The products did not pass through the Technology Assessment Protocol — Ecology(TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/equivalent html 2014 Stormwater Management Manual for Western Washington Volume ll- Chapter 4 -Page 295 BMP C124: Sodding Purpose The purpose of sodding is to establish permanent turf for immediate erosion protection and to stabilize drainage ways where concentrated overland flow will occur. Conditions of Use Sodding may be used in the following areas: . Disturbed areas that require short-term or long-term cover. . Disturbed areas that require immediate vegetative cover. . All waterways that require vegetative lining. Waterways may also be seeded rather than sodded, and protected with a net or blanket. Design and Installation Specifications Sod shall be free of weeds, of uniform thickness (approximately 1-inch thick), and shall have a dense root mat for mechanical strength. The following steps are recommended for sod installation: • Shape and smooth the surface to final grade in accordance with the approved grad- ing plan. The swale needs to be overexcavated 4 to 6 inches below design elev- ation to allow room for placing soil amendment and sod. • Amend 4 inches (minimum) of compost into the top 8 inches of the soil if the organic content of the soil is less than ten percent or the permeability is less than 0.6 inches per hour. See http://www.ecy.wa.gov/programs/swfa/organics/soil.html for further information. . Fertilize according to the supplier's recommendations. . Work lime and fertilizer 1 to 2 inches into the soil, and smooth the surface. . Lay strips of sod beginning at the lowest area to be sodded and perpendicular to the direction of water flow. Wedge strips securely into place. Square the ends of each strip to provide fora close, tight fit. Stagger joints at least 12 inches. Staple on slopes steeper than 3H:1V. Staple the upstream edge of each sod strip. . Roll the sodded area and irrigate. • When sodding is carried out in alternating strips or other patterns, seed the areas between the sod immediately after sodding. 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4-Page 296 Maintenance Standards If the grass is unhealthy, the cause shall be determined and appropriate acti•n taken to reestablish a healthy groundcover. If it is impossible to establish a healthy groundcover due to frequent saturation, instability, or some other cause, the sid sip.IB be removed, the area seeded with an appropriate mix, and protected with a net or blanket. BOO 1 / Corivos rowc Pwpose Topsoiling and composting provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in itself, topsoiling and corn- posting are an integral component of providing permanent cover in those areas where there is an unsuitable soil surface for plant growth. Use this BMP in conjunction with other BMPs such as seeding, mulching, or sodding. Note that this BMP is functionally the same as BMP T5.13: Post-Construction Soil Quality and Depth (p.911) which is required for all disturbed areas that will be developed as lawn or landscaped areas at the completed project site. Native soils and disturbed soils that have been organically amended not only retain much more stormwater, but they also serve as effective biofilters for urban pollutants and, by supporting more vigorous plant growth, reduce the water, fertilizer and pesticides needed to support installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris. Condifaons oil Use • Permanent landscaped areas shall contain healthy topsoil that reduces the need for fertilizers, improves overall topsoil quality, provides for better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation. • Leave native soils and the duff layer undisturbed to the maximum extent prac- ticable. Stripping of existing, properly functioning soil system and vegetation for the purpose of topsoiling during construction is not acceptable. Preserve existing soil systems in undisturbed and uncompacted conditions if functioning properly. o Areas that already have good topsoil, such as undisturbed areas, do not require soil amendments. • Restore,to the maximum extent practical, native soils disturbed during clearing and grading to a condition equal to or better than the original site condition's mois- ture-holding capacity. Use on-site native topsoil, incorporate amendments into on- site soil, or import blended topsoil to meet this requirement. • Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of critically low pH (high acid) levels. 2014 Stormwater Management Manual for Western Washingilcru Volume II- Chapter 4 -Page 297 Mainten ono- Standards If the grass is unhealthy, the cause shall be determined and appropriate action taken to reestablish a healthy groundcoVer. If it is impossible to estab8ish a healthy groundcover due to frequent saturation, instability, or some other cause, the sod shall be removed, the area seeded with an appropriate mix, and protected with a net or blanket. BMP C125: Topsoiling / Composting Purpose Topsoiling and composting provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in itself, topsoiling and corn- posting are an integral component of providing permanent cover in those areas where there is an unsuitable soil surface for plant growth. Use this I,MP in conjunction with other BMPs such as seeding, mulching, or sodding. Note that this BMP is functionally the same as BMP T5.13: Post-Construction Soil Quality and Depth (p.911)which is required for all disturbed areas that will be developed as lawn or landscaped areas at the completed project site. Native soils and disturbed soils that have been organically amended not only retain much more stormwater, but they also serve as effective biofilters for urban pollutants and, by supporting more vigorous plant growth, reduce the water, fertilizer and pesticides needed to support installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris. Conditions of Use • Permanent landscaped areas shall contain healthy topsoil that reduces the need for fertilizers, improves overall topsoil quality, provides for better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation. • Leave native soils and the duff layer undisturbed to the maximum extent prac- ticable. Stripping of existing, properly functioning soil system and vegetation for the purpose of topsoiling during construction is not acceptable. Preserve existing soil systems in undisturbed and uncompacted conditions if functioning properly. • Areas that already have good topsoil, such as undisturbed areas, do not require soil amendments. • Restore, to the maximum extent practical, native soils disturbed during clearing and grading to a condition equal to or better than the original site condition's mois- ture-holding capacity. Use on-site native topsoil, incorporate amendments into on- site soil, or import blended topsoil to meet this requirement. Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of critically low pH (high acid) levels. 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4-Page 297 • Beware of where the topsoil comes from, and what vegetation was on site before disturbance, invasive plant seeds may be included and could cause problems for establishing native plants, landscaped areas, or grasses. • Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will provide optimum conditions for establishing grasses. Use com- mercially available mycorrhiza products when using off-site topsoil. Design and Installation Specifications Meet the following requirements for disturbed areas that will be developed as lawn or landscaped areas at the completed project site: Maximize the depth of the topsoil wherever possible to provide the maximum pos- sible infiltration capacity and beneficial growth medium. Topsoil shall have: A minimum depth of 8-inches. Scarify subsoils below the topsoil layer at least 4-inches with some incorporation of the upper material to avoid stratified lay- ers, where feasible. Ripping or re-structuring the subgrade may also provide additional benefits regarding the overall infiltration and interflow dynamics of the soil system. o A minimum organic content of 10%dry weight in planting beds, and 5% organic matter content in turf areas. Incorporate organic amendments to a minimum 8-inch depth except where tree roots or other natural features limit the depth of incorporation. • A pH between 6.0 and 8.0 or matching the pH of the undisturbed soil. • If blended topsoil is imported, then fines should be limited to 25 percent passing through a 200 sieve. • Mulch planting beds with 2 inches of organic material . Accomplish the required organic content, depth, and pH by returning native topsoil to the site, importing topsoil of sufficient organic content, and/or incorporating organic amendments. When using the option of incorporating amendments to meet the organic content requirement, use compost that meets the compost specification for Bioretention (See BMP T7.30: Bioretention Cells, Swales, and Planter Boxes (p.959)), with the exception that the compost may have up to 35% biosolids or manure. . Sections three through seven of the document entitled, Guidelines and Resources for Implementing Soil Quality and Depth BMP T5.13 in WDOE Stormwater Man- agement Manual for Western Washington, provides useful guidance for imple- menting whichever option is chosen. It includes guidance for pre-approved default strategies and guidance for custom strategies. Check with your local jurisdiction 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 298 concerning its acceptance of this guidance. It is available through the organization, Soils for Salmon.As of this printing the document may be found at: http://www.soils- forsalmon.org/pdf/Soil BMP Manual.pdf. . The final composition and construction of the soil system will result in a natural selection or favoring of certain plant species over time. For example, incorporation of topsoil may favor grasses, while layering with mildly acidic, high-carbon amend- ments may favor more woody vegetation. o Allow sufficient time in scheduling for topsoil spreading prior to seeding, sodding, or planting. © Take care when applying top soil to subsoils with contrasting textures. Sandy top- soil over clayey subsoil is a particularly poor combination, as water creeps along the junction between the soil layers and causes the topsoil to slough. If topsoil and subsoil are not properly bonded, water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method to prevent a lack of bond- ing is to actually work the topsoil into the layer below for a depth of at lest 6 inches. . Field exploration of the site shall be made to determine if there is surface soil of suf- ficient quantity and quality to justify stripping. Topsoil shall be friable and loamy (loam, sandy loam, silt loam, sandy clay loam, and clay loam).Avoid areas of nat- ural ground water recharge. ® Stripping shall be confined to the immediate construction area.A 4-inch to 6-inch stripping depth is common, but depth may vary depending on the particular soil. All surface runoff control structures shall be in place prior to stripping. • Do not place topsoil while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed sodding or seeding. • In any areas requiring grading remove and stockpile the duff layer and topsoil on site in a designated, controlled area, not adjacent to public resources and critical areas. Stockpiled topsoil is to be reapplied to other portions of the site where feas- ible. • Locate the topsoil stockpile so that it meets specifications and does not interfere with work on the site. It may be possible to locate more than one pile in proximity to areas where topsoil will be used. Stockpiling of topsoil shall occur in the following manner: o Side slopes of the stockpile shall not exceed 2H:1 V. . Between October 1 and April 30: 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4-Page 299 . An interceptor dike with gravel outlet and silt fence shall surround all topsoil. . Within 2 days complete erosion control seeding, or covering stockpiles with clear plastic, or other mulching materials. . Between May 1 and September 30: . An interceptor dike with gravel outlet and silt fence shall surround all topsoil if the stockpile will remain in place for a longer period of time than active construction grading. . Within 7 days complete erosion control seeding, or covering stockpiles with clear plastic, or other mulching materials. . When native topsoil is to be stockpiled and reused the following should apply to ensure that the mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed: 1. Re-install topsoil within 4 to 6 weeks. 2. Do not allow the saturation of topsoil with water. 3. Do not use plastic covering. Maintenance Standards . Inspect stockpiles regularly, especially after large storm events. Stabilize any areas that have eroded. . Establish soil quality and depth toward the end of construction and once estab- lished, protect from compaction, such as from large machinery use, and from erosion. . Plant and mulch soil 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. BMP C126: Polyacrylamide (PAM) for Soil Erosion Protection Purpose Polyacrylamide (PAM) is used on construction sites to prevent soil erosion. Applying PAM to bare soil in advance of a rain event significantly reduces erosion and controls sediment in two ways. First, PAM increases the soil's available pore volume, 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 300 BMP C140: Dust Control Purpose Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, drainage ways, and surface waters. Conditions of Use . In areas (including roadways) subject to surface and air movement of dust where on-site and off-site impacts to roadways, drainage ways, or surface waters are likely. Design and Installation Specifications . Vegetate or mulch areas that will not receive vehicle traffic. In areas where plant- ing, mulching, or paving is impractical, apply gravel or landscaping rock. . Limit dust generation by clearing only those areas where immediate activity will take place, leaving the remaining area(s) in the original condition. Maintain the ori- ginal ground cover as long as practical. . Construct natural or artificial windbreaks or windscreens. These may be designed as enclosures for small dust sources. . Sprinkle the site with water until surface is wet. Repeat as needed. To prevent carryout of mud onto street, refer to BMP C 105: Stabilized Construction Entrance / Exit(p.270). . Irrigation water can be used for dust control. Irrigation systems should be installed as a first step on sites where dust control is a concern. . Spray exposed soil areas with a dust palliative, following the manufacturer's instructions and cautions regarding handling and application. Used oil is pro- hibited from use as a dust suppressant. Local governments may approve other dust palliatives such as calcium chloride or PAM. . PAM (BMP C126: Polyacrylamide (PAM)for Soil Erosion Protection (p.300)) added to water at a rate of 0.5 lbs. per 1,000 gallons of water per acre and applied from a water truck is more effective than water alone. This is due to increased infilt- ration of water into the soil and reduced evaporation. In addition, small soil particles are bonded together and are not as easily transported by wind.Adding PAM may actually reduce the quantity of water needed for dust control. Use of PAM could be a cost-effective dust control method. Techniques that can be used for unpaved roads and lots include: 2014 Stormwater Management Manual for Western Washington Volume ii- Chapter 4 - Page 310 . Lower speed limits. High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. . Upgrade the road surface strength by improving particle size, shape, and mineral types that make up the surface and base materials. . Add surface gravel to reduce the source of dust emission. Limit the amount of fine particles (those smaller than .075 mm)to 10 to 20 percent. . Use geotextile fabrics to increase the strength of new roads or roads undergoing reconstruction. . Encourage the use of alternate, paved routes, if available. . Restrict use of paved roadways by tracked vehicles and heavy trucks to prevent damage to road surface and base. . Apply chemical dust suppressants using the admix method, blending the product with the top few inches of surface material. Suppressants may also be applied as surface treatments. . Pave unpaved permanent roads and other trafficked areas. . Use vacuum street sweepers. . Remove mud and other dirt promptly so it does not dry and then turn into dust. • Limit dust-causing work on windy days. . Contact your local Air Pollution Control Authority for guidance and training on other dust control measures. Compliance with the local Air Pollution Control Authority constitutes compliance with this BMP. Maintenance Standards Respray area as necessary to keep dust to a minimum. BMP C150: Materials on Hand Purpose Keep quantities of erosion prevention and sediment control materials on the project site at all times to be used for regular maintenance and emergency situations such as unex- pected heavy summer rains. Having these materials on-site reduces the time needed to implement BMPs when inspections indicate that existing BMPs are not meeting the Con- struction SWPPP requirements. In addition, contractors can save money by buying some materials in bulk and storing them at their office or yard. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 311 BMP C207: Check Dams Purpose Construction of small dams across a swale or ditch reduces the velocity of concentrated flow and dissipates energy at the check dam. Conditions of Use Where temporary channels or permanent channels are not yet vegetated, channel lining is infeasible, and/or velocity checks are required. . Check dams may not be placed in streams unless approved by the State Depart- ment of Fish and Wildlife. Check dams may not be placed in wetlands without approval from a permitting agency. . Do not place check dams below the expected backwater from any salmonid bear- ing water between October 1 and May 31 to ensure that there is no loss of high flow refuge habitat for overwintering juvenile salmonids and emergent salmonid fry. • Construct rock check dams from appropriately sized rock. The rock used must be large enough to stay in place given the expected design flow through the channel. The rock must be placed by hand or by mechanical means (no dumping of rock to form dam)to achieve complete coverage of the ditch or swale and to ensure that the center of the dam is lower than the edges. . Check dams may also be constructed of either rock or pea-gravel filled bags. Numerous new products are also available for this purpose. They tend to be re- usable, quick and easy to install, effective, and cost efficient. . Place check dams perpendicular to the flow of water. . The dam should form a triangle when viewed from the side. This prevents under- cutting as water flows over the face of the dam rather than falling directly onto the ditch bottom. . Before installing check dams impound and bypass upstream water flow away from the work area. Options for bypassing include pumps, siphons, or temporary chan- nels. . Check dams in association with sumps work more effectively at slowing flow and retaining sediment than just a check dam alone. A deep sump should be provided immediately upstream of the check dam. . In some cases, if carefully located and designed, check dams can remain as per- manent installations with very minor regrading. They may be left as either spill- ways, in which case accumulated sediment would be graded and seeded, or as 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 352 check dams to prevent further sediment from leaving the site. . The maximum spacing between the dams shall be such that the toe of the upstream dam is at the same elevation as the top of the downstream dam. . Keep the maximum height at 2 feet at the center of the dam. . Keep the center of the check dam at least 12 inches lower than the outer edges at natural ground elevation. . Keep the side slopes of the check dam at 2H:14/or flatter. . Key the stone into the ditch banks and extend it beyond the abutments a minimum of 18 inches to avoid washouts from overflow around the dam. . Use filter fabric foundation under a rock or sand bag check dam. If a blanket ditch liner is used, filter fabric is not necessary.A piece of organic or synthetic blanket cut to fit will also work for this purpose. . In the case of grass-lined ditches and swales, all check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale- unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. . Ensure that channel appurtenances, such as culvert entrances below check dams, are not subject to damage or blockage from displaced stones. Figure 11-4.2.7 Rock Check Dam (p.354) depicts a typical rock check dam. GiairraenancP. Standards Check dams shall be monitored for performance and sediment accumulation during and after each runoff producing rainfall. Sediment shall be removed when it reaches one half the sump depth. . Anticipate submergence and deposition above the check dam and erosion from high flows around the edges of the dam. . If significant erosion occurs between dams, install a protective riprap liner in that portion of the channel. Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C207: Check Dams. The products did not pass through the Technology Assessment Protocol®Eco- logy (TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa.gov_- /programs/wq/stormwater/newtech/equivalent.html 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 353 Figure 11-4.2.7 Rock Check Dam View Looking Upstream A 18" 12" ("rn) J `150mm) Note: //'l Key stone into channel banks and extend it beyond the abutments a minimum of 18" i>> (0.5m)to prevent flow around dam. _ A Section A-A Flow 24"24"(0.6m) �-- 8'(2.4m) Spacing Between Check Dams 'L'=the distance such that points 'A'and'B'are of equal elevation. Point'A' Point'B' •o NOT TO SCALE ...►1 Figure I I-4.2.7 Rock Check Dam DEPARTMENT OF Revised July 2015 ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability,and disclaimer. 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4-Page 354 1. If the discharge velocity at the outlet is less than 5 fps (pipe slope less than 1 percent), use 2-inch to 8-inch riprap. Minimum thickness is 1-foot. 2. For 5 to 10 fps discharge velocity at the outlet(pipe slope less than 3 per- cent), use 24-inch to 48-inch riprap. Minimum thickness is 2 feet. 3. For outlets at the base of steep slope pipes (pipe slope greater than 10 per- cent), an engineered energy dissipater shall be used. . Filter fabric or erosion control blankets should always be used under riprap to pre- vent scour and channel erosion. • New pipe outfalls can provide an opportunity for low-cost fish habitat improve- ments. For example, an alcove of low-velocity water can be created by con- structing the pipe outfall and associated energy dissipater back from the stream edge and digging a channel, over-widened to the upstream side,from the outfall. Overwintering juvenile and migrating adult salmonids may use the alcove as shel- ter during high flows. Bank stabilization, bioengineering, and habitat features may be required for disturbed areas. This work may require a HPA. See Volume V (p.765)for more information on outfall system design. Maintenance Standards . Inspect and repair as needed. . Add rock as needed to maintain the intended function. . Clean energy dissipater if sediment builds up. BMP C220: Storm Drain Inlet Protection Purpose Storm drain inlet protection prevents coarse sediment from entering drainage systems prior to permanent stabilization of the disturbed area. Conditions of Use Use storm drain inlet protection at inlets that are operational before permanent sta- bilization of the disturbed drainage area. Provide protection for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless conveying run- off entering catch basins to a sediment pond or trap. Also consider inlet protection for lawn and yard drains on new home construction.These small and numerous drains coupled with lack of gutters in new home construction can add significant amounts of sediment into the roof drain system. If possible delay installing lawn and yard drains until just before landscaping or cap these drains to pre- 2014 Stormwater Management Manual for Western Washington Volume ll- Chapter 4-Page 357 vent sediment from entering the system until completion of landscaping. Provide 18- inches of sod around each finished lawn and yard drain. Table 11-4.2.2 Storm Drain Inlet Protection (p.358) lists several options for inlet protection. All of the methods for storm drain inlet protection tend to plug and require a high fre- quency of maintenance. Limit drainage areas to one acre or less. Possibly provide emer- gency overflows with additional end-of-pipe treatment where stormwater ponding would cause a hazard. Table 11-4.2.2 Storm Drain Inlet Protection Type of Inlet m y ergers Applicable for Waved/Ear Protec f iOn 4 er#lEarthen Conditions of Ils• e Surfaces: Drop.Inlet Protection Excavated drop Yes, tern- Applicable for heavy flows. Easy protection porary flood- Earthen to maintain. Large area Require- inleting will occur ment: 305(301/acre Block and Applicable for heavy concentrated gravel drop inlet Yes Paved or Earthen flows. Will not pond. protection Gravel and wire Applicable for heavy concentrated drop inlet pro- No flows. Will pond. Can withstand tection traffic. Catch basin fil- Yes Paved or Earthen Frequent Maintenance required. ters Curb Inlet Protection Curb inlet pro- tection with Small capacity Paved Used for sturdy, more compact wooden weir overflow installation. Block and gravel curb inlet Yes Paved Sturdy, but limited filtration. protection Culvert Inlet Protection Culvert inlet Sed 18 month expected life. iment trap Design and Installation Specifications Excavated Drop Inlet Protection-An excavated impoundment around the storm drain. Sediment settles out of the stormwater prior to entering the storm drain. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 - Page 358 . Provide a depth of 1-2 ft as measured from the crest of the inlet structure. . Slope sides of excavation no steeper than 2H:1 V. . Minimum volume of excavation 35 cubic yards. . Shape basin to fit site with longest dimension oriented toward the longest inflow area. • Install provisions for draining to prevent standing water problems. . Clear the area of all debris. . Grade the approach to the inlet uniformly. . Drill weep holes into the side of the inlet. . Protect weep holes with screen wire and washed aggregate. . Seal weep holes when removing structure and stabilizing area. . Build a temporary dike, if necessary, to the down slope side of the structure to pre- vent bypass flow. Block and Gravel Filter-A barrier formed around the storm drain inlet with standard con- crete blocks and gravel. See Figure 11-4.2.8 Block and Gravel Filter(p.360). . Provide a height of 1 to 2 feet above inlet. . Recess the first row 2-inches into the ground for stability. . Support subsequent courses by placing a 2x4 through the block opening. . Do not use mortar. . Lay some blocks in the bottom row on their side for dewatering the pool. . Place hardware cloth or comparable wire mesh with %-inch openings over all block openings. . Place gravel just below the top of blocks on slopes of 2H:1 V or flatter. . An alternative design is a gravel donut. . Provide an inlet slope of 3H:1 V. . Provide an outlet slope of 2H:1V. . Provide a 1-foot wide level stone area between the structure and the inlet. . Use inlet slope stones 3 inches in diameter or larger. • Use gravel 1/2-to %-inch at a minimum thickness of 1-foot for the outlet slope. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 359 (Rcoju1f2G Q:-.-' a2a`C) Q ��ft @ACstA CL-6w, q© fo_v Drain grate ° 94004 ` oQ . o•, •. 'q�g)o oo:o' cpeAp$ Concrete block 07 Qr oo �` Q▪ I v Q 1 On`Y p a a o 11 [II][iL- t Gravel backfill 4• Pr1 p 6(� . )pS L,-1;44170) 000000 ripE o ,e ,.&)./.;:it,":•Illb- ��GJ 5��e . L-boD� M &°°° <0 A pain View Concrete block Wire screen or filter fabric Gravel backfill ___,ems Overflow water Ponding height cos-. a Water \ \ :\\. \ V\A\.\s' > i \ \ \/\/\' / ./i\`/> \ \ \ \\ Drop inlet /\\/\ \/\ \ Section A=A Notes: 1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less than 5%) 2. Excavate a basin of sufficient size adjacent to the drop inlet. 3. The top of the structure (ponding height) must be well below the ground elevation downslope to prevent runoff from bypassing the inlet.A temporary dike may be necessary on the downslope side of the structure. NOT TO SCALE s''- ill - o g u re L4.2.8 Block and Gravel Filter DEPARTMENT O F Revised August 2015 E Co_®'Y Please see http://www.ecy.wa.govlcopyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Stoowater Management Manual for Western Washington Volume ll - Chapter 4 - Page 360 Gravel and Wire Mesh Filter-A gravel barrier placed over the top of the inlet. This struc- ture does not provide an overflow. . Use a hardware cloth or comparable wire mesh with 1/2-inch openings. . Use coarse aggregate. . Provide a height 1-foot or more, 18-inches wider than inlet on all sides. . Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot beyond each side of the inlet structure. . Overlap the strips if more than one strip of mesh is necessary. . Place coarse aggregate over the wire mesh. . Provide at least a 12-inch depth of gravel over the entire inlet opening and extend at least 18-inches on all sides. Catchbasin Filters—Use inserts designed by manufacturers for construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. To reduce maintenance require- ments combine a catchbasin filter with another type of inlet protection.This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights-of-way. . Provides 5 cubic feet of storage. . Requires dewatering provisions. . Provides a high-flow bypass that will not clog under normal use at a construction site. . Insert the catchbasin filter in the catchbasin just below the grating. Curb Inlet Protection with Wooden Weir— Barrier formed around a curb inlet with a wooden frame and gravel. . Use wire mesh with %z-inch openings. . Use extra strength filter cloth. . Construct a frame. . Attach the wire and filter fabric to the frame. . Pile coarse washed aggregate against wire/fabric. . Place weight on frame anchors. Block and Gravel Curb Inlet Protection— Barrier formed around a curb inlet with concrete blocks and gravel. See Figure II-4.2.9 Block and Gravel Curb Inlet Protection (p.363). 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 361 • Use wire mesh with '/winch openings. • Place two concrete blocks on their sides abutting the curb at either side of the inlet opening. These are spacer blocks. • Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. • Place blocks on their sides across the front of the inlet and abutting the spacer blocks. • Place wire mesh over the outside vertical face. • Pile coarse aggregate against the wire to the top of the barrier. Curb and Gutter Sediment Barrier—Sandbag or rock berm (riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure I1 4.2.10 Curb and Gutter Barrier (p.364). • Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. • Construct a horseshoe shaped sedimentation trap on the outside of the berm sized to sediment trap standards for protecting a culvert inlet. Maintenance Standards • Inspect catch basin filters frequently, especially after storm events. Clean and replace clogged inserts. For systems with clogged stone filters: pull away the stones from the inlet and clean or replace.An alternative approach would be to use the clogged stone as fill and put fresh stone around the inlet. • Do not wash sediment into storm drains while cleaning. Spread all excavated material evenly over the surrounding land area or stockpile and stabilize as appro- priate. Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C220: Storm Drain Inlet Protection. The products did not pass through the Technology Assessment Protocol —Ecology (TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa.gov/programs/wq/stormwater/newtech/eq uivalent.html 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 362 isanamm IB, a2ocl - t5© 3JEUc® T1-6U°&-R/A Cum* [AGA G;U°©il©(0,aoH . \/,,:y-- Catch basin Back of sidewalk 2x4 Back of curb Curb inlet ConcreteWoodstud block „., ,,,,. „,,,,,.4,7 i #"! .4,'!:-/k.Ii. '.'''M St:4.47.2 .-::- .. ire screen or ,.0 . . Ie` •,..,4 , ,,,, ,• . �.1;, ; rW;. , ;.. filter fabric ;Qa +'4.�+ 7 ,i� `ti!Ik.�!r o jti+ 4,.0 0.,4 ic'O a•..+:„.••.p 3/4 inch (20 mm) Concrete block Drain gravel Fan View Ponding height 3/4 inch (20 mm) - Drain gravel Overflow . ,----t-1-41.-zglifi pi 0 k .,/, Curb inlet �j Wire screen or \��/ 1. \ \</' filter fabric 2x4 Wood stud '>" A (100x50 Timber stud) ;, Catch basin �\' Concrete block SectiinA—A Notes: 1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shall allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. NOT TO SCALE bat e ... ii Figure 0-4.2. 9 lowiii Block and Gravel Curb fillet protection DEPARTMENT OF Revised August 2015 E C O _ G Y Please see http://www.ecywa.govicopright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Stormwater Manage meat Manual for Western Washington Volume II o Chapter 4 - Page 363 Back of sidewalk — Burlap sacks to overlap onto curb Back of curb Curb inlet Runoff Runoff Spillway � � fCatch basin G Pan Mew LI/ Gravel filled sandbags stacked tightly Notes: 1. Place curb type sediment barriers on gently sloping street segments, where water can pond and allow sediment to separate from runoff. 2. Sandbags of either burlap or woven 'geotextiie'fabric, are filled with gravel, layered and packed tightly. 3. Leave a one sandbag gap in the top row to provide a spillway for overflow. 4. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. NOT TO SCALE 11111311011 Hguwe1-4.2e1O weig Curb and Gu f-?r Barrier DEPARTMENT OF Revised September 2015 Clr� Please see htfp:lhvww.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Storrowater Management Manual for Western Washington Volume II - Chapter 4 Page 364 Purpose A gravel filter berm is constructed on rights-of-way or traffic res within nsfrructi.n site to retain sediment by using a filter berm of gravel or crushed rock. Conditions c•f Use When- a temporary measure is needed to retain sediment fr.m rights-of-way or in traffic areas on construction sites. Design and inst ail tLoon Specifocs oohs • Berm material shall be 3/to 3 inches in size, washed well-grade gravel or crushed rock with less than 5 percent fines. o Spacing of berms: • Every 300 feet on slopes less than 5 percent o Every 200 feet on slopes between 5 percent and 10 percent O Every 100 feet on slopes greater than 10 percent • germ dimensions: • 1 foot high with 3H:1V side slopes O 8 linear feet per 1 cfs ru-off based on the 10-year, 24-hour design storm Glaanganenwa Man rds • Regular inspection is required. Sediment shall be removed and filter material replaced as needed. Ri`dI' C233o Fans Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. See Figure I1-4.2.12 Silt Fence (p.369)for details on silt fence con- struction. Conditions of Use Silt fence may be used downslope of all disturbed areas. 2014 Stormwater Management Manual for Western Washington Volume d0 0 Ch pter 4-Page 367 BMP C232: Gravel Filter Berm Purposs A gravel filter berm is constructed on rights-of-way or traffic areas within a construction site to retain sediment by using a filter berm of gravel or crushed rock. Conditions of Use Where a temporary measure is needed to retain sediment from rights-of--way or in traffic areas on construction sites. Design and Installation Specifications • Berm material shall be%to 3 inches in size, washed well-grade gravel or crushed rock with less than 5 percent fines. • Spacing of berms: • Every 300 feet in slopes less than 5 percent o Every 200 feet on slopes between 5 percent and 10 percent o Every 100 feet on slopes greater than 10 percent • Berm dimensions: O 1 foot high with 3H:1V side slopes O 8 linear feet per 1 cfs runoff based on the 10-year, 24-hour design storm Maintenance Standards Regular inspection is required. Sediment shall be removed and filter material replaced as needed. BMP C233: Silt Fence Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. See Figure 11-4.2.12 Silt Fence (p.369)for details on silt fence con- struction. Conditions of Use Silt fence may be used downslope of all disturbed areas. 2014 Stormwater Management Manual for Western Washington Volume II- Ch Ater 4-Page 367 • Silt fence shall prevent soil carried by runoff water from going beneath, through, or over the top of the silt fence, but shall allow the water to pass through the fence. • Silt fence is not intended to treat concentrated flows, nor is it intended to treat sub- stantial amounts of overland flow. Convey any concentrated flows through the drainage system to a sediment pond. • Do not construct silt fences in streams or use in V-shaped ditches. Silt fences do not provide an adequate method of silt control for anything deeper than sheet or overland flow. 2014 Stormwater Management Manual for Western Washington Volume II®Chapter 4®Page 368 Joints in filter fabric shall be spliced at posts. Use staples, wire rings or equivalent to attach fabric to posts 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used II ��+••+•� ■e�uu.wu' me ( ••+•+•• • i*** vmiau /cul■ ii '�+•��4*• • • ....SS,an■.eern■■ ' uA *••+*•••• • IN I II a.uu�1 gnu. +••••••• /I.•*•••••." _uIua MIrn •*••*••. eani■ ■■ ••••••+••• MMi■ ■A■Pt•**•••*•• ■••i�1 •/•+•+**•+•••••*+.04,4. •••••••••••� � e- +*�•4*4 `+•:•+•+*++•••••*'••440•••:•*•••:**••+�'•• *:••••••404:4.i4:'�i u u I IIii �••••♦• •••*•••+•••••*•••••••+••••••••••••••••+••••••••••••••••••❖•t0 D►s..►,►,i u■ RI "•♦•dtt •••••***•• ••• •••••••••••••••••••�••••••+••••••••+•••••+••••! N► . �4 v 11■ MU II.�..•,- *.,01, *•*++•*•••O... • •••.••+••••+•+•+•+••••••••••••••••++,*i► i►ti►iI fl w mm rnI / / •+..•i... ...A*Qiii*�. / \�� t. ./,�S,_ Pi P�/\ I f \��\l�\��\,�\��\\/�\\ \\ \\�\\f�\\ s\ �� .\ '�� (�\ /. III • I I Minimum { I 6' max 4"x4"trench I 1 I L Post spacing may be increased y to 8' if wire backing is used 2"x2"wood posts, steel fence posts, or equivalent 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used ■I / / :i \\\\ Filter fabric ;I •I 4k\ :El i 2' min \\ \ NI NI \\ \\\ NI u Backlit trench with �///\ . :.:N _ masa native soil or Ati - / •s•.it 1.5"washed gravel -•:•� \\�/\„/.\/\ \ \ \/\\gym'////\\//•/ Minimum \ \/�, 4"x4"trench 2"x2"wood posts, steel fence posts, or equivalent NOT TO SCALE align= 1111: 11 ifft Fence DEPARTMENT OF Revised October 2014 E C ® L®G Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Stormwater Management Manual for Western Washington • Volume II o Chapter 4 - Page 369 Design and Installation Specifications . Use in combination with sediment basins or other BMPs. . Maximum slope steepness (normal (perpendicular)to fence line) 1 H:1V. . Maximum sheet or overland flow path length to the fence of 100 feet. . Do not allow flows greater than 0.5 cfs. . The geotextile used shall meet the following standards. All geotextile properties lis- ted below are minimum average roll values (i.e., the test result for any sampled roll in a lot shall meet or exceed the values shown in Table 11-4.2.3 Geotextile Stand- ards (p.370)): Table 11-4.2.3 Geotextile Standards 0.60 mm maximum for slit film woven (#30 sieve). Polymeric Mesh AOS 0.30 mm maximum for all other geotextile types (#50 sieve). (ASTM D4751) 0.15 mm minimum for all fabric types (#100 sieve). Water Permittivity 0.02 sec-1 minimum (ASTM D4491) Grab Tensile Strength 180 lbs. Minimum for extra strength fabric. (ASTM D4632) 100 lbs minimum for standard strength fabric. Grab Tensile Strength 30% maximum (ASTM D4632) Ultraviolet Resistance 70% minimum (ASTM D4355) • Support standard strength fabrics with wire mesh, chicken wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the fabric. Silt fence materials are available that have synthetic mesh backing attached. • Filter fabric material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable construction life at a temperature range of 0°F. to 120°F. . One-hundred percent biodegradable silt fence is available that is strong, long last- ing, and can be left in place after the project is completed, if permitted by local reg- ulations. . Refer to Figure 11-4.2.12 Silt Fence (p.369) for standard silt fence details. Include the following standard Notes for silt fence on construction plans and specifications: 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 370 1. The contractor shall install and maintain temporary silt fences at the locations shown in the Plans. 2. Construct silt fences in areas of clearing, grading, or drainage prior to starting those activities. 3. The silt fence shall have a 2-feet mien. and a 21/2-feet max. height above the original ground surface. 4. The filter fabric shall be sewn together at the point of manufacture to form fil- ter fabric lengths as required. Locate all sewn seams at support posts.Altern- atively, two sections of silt fence can be overlapped, provided the Contractor can demonstrate, to the satisfaction of the Engineer, that the overlap is long enough and that the adjacent fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. 5. Attach the filter fabric on the up-slope side of the posts and secure with staples,wire, or in accordance with the manufacturer's recommendations. Attach the filter fabric to the posts in a manner that reduces the potential for tearing. 6. Support the filter fabric with wire or plastic mesh, dependent on the properties of the geotextile selected for use. If wire or plastic mesh is used, fasten the mesh securely to the up-slope side of the posts with the filter fabric up-slope of the mesh. 7. Mesh support, if used, shall consist of steel wire with a maximum mesh spa- cing of 2-inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to the same level of ultra- violet radiation as the filter fabric it supports. 8. Bury the bottom of the filter fabric 4-inches min. below the ground surface. Backfill and tamp soil in place over the buried portion of the filter fabric, so that no flow can pass beneath the fence and scouring cannot occur. When wire or polymeric back-up support mesh is used, the wire or polymeric mesh shall extend into the ground 3-inches min. 9. Drive or place the fence posts into the ground 18-inches min.A 12—inch min. depth is allowed if topsoil or other soft subgrade soil is not present and 18- inches cannot be reached. Increase fence post min. depths by 6 inches if the fence is located on slopes of 3H:1V or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to prevent overturning of the fence due to sediment loading. 10. Use wood, steel or equivalent posts. The spacing of the support posts shall 2014 Stormwater Management Manual for Western Washington Volume lI- Chapter 4 -Page 371 be a maximum of 6-feet. Posts shall consist of either: . Wood with dimensions of 2-inches by 2-inches wide min. and a 3-feet min. length. Wood posts shall be free of defects such as knots, splits, or gouges. . No. 6 steel rebar or larger. o ASTM A 120 steel pipe with a minimum diameter of 1-inch. • U, 1, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. o Other steel posts having equivalent strength and bending resistance to the post sizes listed above. 11. Locate silt fences on contour as much as possible, except at the ends of the fence, where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. 12. If the fence must cross contours, with the exception of the ends of the fence, place gravel check dams perpendicular to the back of the fence to minimize concentrated flow and erosion. The slope of the fence line where contours must be crossed shall not be steeper than 3H:1 V. . Gravel check dams shall be approximately 1-foot deep at the back of the fence. Gravel check dams shall be continued perpendicular to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. . Gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. Gravel check dams shall be located every 10 feet along the fence where the fence must cross con- tours. . Refer to Figure 11-4.2.13 Silt Fence Installation by Slicing Method (p.374)for slicing method details. Silt fence installation using the slicing method specifications: 1. The base of both end posts must be at least 2-to 4-inches above the top of the filter fabric on the middle posts for ditch checks to drain properly. Use a hand level or string level, if necessary, to mark base points before install- ation. 2. Install posts 3-to 4-feet apart in critical retention areas and 6-to 7-feet apart in standard applications. 3. Install posts 24-inches deep on the downstream side of the silt fence, and as close as possible to the filter fabric, enabling posts to support the filter fabric from upstream water pressure. 4. Install posts with the nipples facing away from the filter fabric. 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4 -Page 372 5. Attach the filter fabric to each post with three ties, all spaced within the top 8- inches of the filter fabric. Attach each tie diagonally 45 degrees through the fil- ter fabric, with each puncture at least 1-inch vertically apart. Each tie should be positioned to hang on a post nipple when tightening to prevent sagging. 6. Wrap approximately 6-inches of fabric around the end posts and secure with 3 ties. 7. No more than 24-inches of a 36-inch filter fabric is allowed above ground level. Compact the soil immediately next to the filter fabric with the front wheel of the tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the upstream side first and then each side twice for a total of four trips. Check and correct the silt fence installation for any deviation before compaction. Use a flat-bladed shovel to tuck fabric deeper into the ground if necessary. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 - Page 373 Lrllgauv© E,- 1,U2o t 3 Mn[l= L2c=-)v-ice, flcr-flolLnEriald rf--o Cry aoc oRrDr Gt© he Ponding height max. 24" ';. 1--1 POST SPACING: 7` max. on open runs Attach fabric to l 4' max. on pooling areas - Top of Fabric upstream side of post . _- •� � Belt FLOW =1 POST DEPTH: top 8" Drive over each side of =j ► As much below ground ), silt fence 2 to 4 times • as fabric above ground with device exerting 60 p.s.i. or greater Diagonal attachment 100% compaction • 100% compaction doubles strength -i I I=111=1 T 1=1 I 11 I-1 11-111-111- 1 I-1 I I=1I-III-III-I I=111:I I 1:111-1 1-I l 1: •■.... �■ =111-111=1 I 1-111 III-►11-1►►-i l 1-111f-1 '"" 1-11 I-111I-111=1' �, 1—I I I=1111E111E-111-111I '. 1TI111►I►I11► 411141► 8.1E11111111f 11111111111111 -114=111=411=11 t 411=141=411=411=111= Attachment Details: =i 11=1 I I-1 j I 01t 11=f I m I I I h I I I-1 I I 1 1 ll=(I I-I I i 4 a ti—!11-111-1 l(-(I t= 0 Gather fabric at posts, if needed. -111=111=1I •�:. N I=1 I I-1 I 1-1 I I—III-1I' 0 Utilize three ties per post, all within top 8" 11111111='` III-111III=111-111E -Ill-111=111=1l: 1=)11�111-111E11I—II of fabric. I I-111-1 I I-III 111E-11�I 11-111=11 F- 0 Position each tie diagonally, puncturing -1 l i-11►1-11 E1_I is`n 1-f 11-ME-11 f�FR-1' '1-111E111I11- 11I-111=11 =111-1 r holes vertically a minimum of 1"apart. 111E111E111-111: 1f1 l 1-111E111I' 0 Hang each tie on a post nipple and tighten No more than 24" of a 36" securely. Use cable ties (50 Ibs) or soft fabric is allowed above ground wire. ; . Roll of silt fence — Operation ', ;N�1 ✓�,. Post installed 1� Fabric after l above compaction 1,, ground Silt Fence p-- L 111E-111-111E111E-111EIII►►41- \ i '��II /111E11 200 - 1=111111 1-11191-41-141-11411-144-14_1 411 11111►11„, 11ll'1f ' t, 114 300mm 14{�114=1 11E14 I I-1I f-LI =1I1=1Il=1I!-II _. . _ 1`ll 1 `11` 1 I II_IIT 11=1II(IIIIIIIiTlllll1111111111111�II I_II I(1S ill�III111i1`I1I11IIiI�11I1I11II !4 =441 [ -. . IliI 11�11 1--1 11-- -I I-iii 1 1 11 1 1 I 1 11(--I 11^I 1 1+- I I '�I 11 l 11 Horizontal chisel point Slicing blade (76 mm width) (18 mm width) Completed Installation Vibratory plow is not acceptable because of horizontal compaction NOT TO SCALE SiVAilli t Fence linst 9Dat on by Slicing Method DEPARTMENT 0 F Revised November 2015 ECOLOGY _ Please see htfpJ/www.ecy.wa.gov/copyright.hfml for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Stormmwater Management Manual for Western Washington Volume ll - Chapter 4 - Page 374 daintenance Standards . Repair any damage immediately. . Intercept and convey all evident concentrated flows uphill of the silt fence to a sed- iment pond. . Check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. . Remove sediment deposits when the deposit reaches approximately one-third the height of the silt fence, or install a second silt fence. • Replace filter fabric that has deteriorated due to ultraviolet breakdown. ndi\LP 1!1egol'c ®Cd7 strip Purpose Vegetated strips reduce the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. Conditions of Use o Vegetated strips may be used downslope of all disturbed areas. . Vegetated strips are not intended to treat concentrated flows, nor are they intended to treat substantial amounts of overland flow. Any concentrated flows must be con- veyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a strip, rather than by a sediment pond, is when the following criteria are met(see Table 11-4.2.4 Contributing Drain- age Area for Vegetated Strips (p.375)): Table 11-4.2.4 Contributing Drainage Area for Vegetated Strips Average Contributing Average Contributing Area Max Contributing area Area Slope Percent Slope Flowpath Length 1.5H : 1 V or flatter 67% or flatter 100 feet 2H : 1 V or flatter 50% or flatter 115 feet 4H : 1 V or flatter 25% or flatter 150 feet 6H : 1 V or flatter 16.7% or flatter 200 feet 10H : 1 V or flatter 10% or flatter 250 feet 2014 Stormwater Management Manual for Western Washington Volume Il- Chapter 4-Page 375 Design and inst2lIaffoon Specifications • The vegetated strip shall consist of a minimum of a 25-foot flowpath length con- tinuous strip of dense vegetation with topsoil. Grass-covered, landscaped areas are generally not adequate because the volume of sediment overwhelms the grass. Ideally, vegetated strips shall consist of undisturbed native growth with a well-developed soil that allows for infiltration if runoff. • The slope within the strip shall not exceed 4H:1 V. o The uphill boundary of the vegetated strip shall be delineated with clearing limits. Ali intenance Standards • Any areas damaged by erosion or construction activity shall be seeded imme- diately and protected by mulch. © If more than 5 feet of the original vegetated strip width has had vegetation removed or is being eroded, sod must be installed. . If there are indications that concentrated flows are traveling across the buffer, sur- face water controls must be installed to reduce the flows entering the buffer, or addi- tional perimeter protection must be installed. BMP C235: Wattles Purpose Wattles are temporary erosion and sediment control b_:rriers consisting of straw, com- post, or other material that is wrapped in biodegradable tubular plastic or similar encas- ing material. They reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sediment. Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length. Wattles are placed in shallow trenches and staked along the contour of disturbed or newly constructed slopes. See Figure 11-4.2.14 Wattles (p.378) for typical construction details. WSDOT Standard Plan 1-30.30-00 also provides information on Wattles (http://www.wsdot.wa.gov/Design/Standarols/P1arlSohtm#Sectionl) Conditions of Use Use wattles: . In disturbed areas that require immediate erosion protection. • On exposed soils during the period of short construction delays, or over winter months. • On slopes requiring stabilization until permanent vegetation can be estab- lished. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 - Page 376 . The material used dictates the effectiveness period of the wattle. Generally, Wattles are typically effective for one to two seasons. . Prevent rilling beneath wattles by properly entrenching and abutting wattles together to prevent water from passing between them. Design Criteria . Install wattles perpendicular to the flow direction and parallel to the slope contour. . Narrow trenches should be dug across the slope on contour to a depth of 3-to 5- inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas with high rainfall, the trenches should be dug to a depth of 5-to 7- inches, or 1/2 to 2/3 of the thickness of the wattle. . Start building trenches and installing wattles from the base of the slope and work up. Spread excavated material evenly along the uphill slope and compacted using hand tamping or other methods. . Construct trenches at intervals of 10-to 25-feet depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches. . Install the wattles snugly into the trenches and abut tightly end to end. Do not over- lap the ends. . Install stakes at each end of the wattle; and at 4-foot centers along entire length of wattle. . If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. . Wooden stakes should be approximately 3/4 x 3/4 x 24 inches min. Willow cuttings or 3/8-inch rebar can also be used for stakes. . Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake protruding above the wattle. Maintenance Standards . Wattles may require maintenance to ensure they are in contact with soil and thor- oughly entrenched, especially after significant rainfall on steep sandy soils. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 377 Figure 11-4.2.14 Wattles 3' -4' \‘ .` (1.2m) ®� Mck Yi o%f►'' 0/� V \ ' ,\\b ?W��{ i 'OAP; �� \ \\ \' i• ♦ 1 Straw rolls must be ,rim , ,g placed along slope ��j;•, \ U1 Adjacent rolls contours . \ shall tightly abut \ • \j// PA I^ Al/ • \ ♦.f \�\! � r�. +yam` �f. �. ee , lb' - 25' (3-8m) / , 4t, YY /CNN `II� Ncy \ Spacing depends ; on soil type and rd slope steepness �'�j1+.fie Sediment, organic matter, V and native seeds are `'+. . captured behind the rolls. �� / &' • 3" - 5" (75-125mm) %\ .. 1 ? \ ,/\ s"- 10" Dia. / ��\\ \ (200-250mm) oreiii Live Stake r,_�-!�� \`. // 1" x 1" Stake \�� ! . � (25 x 25mm) 4 t k NOTE: 1. Straw roll installation requires the placement and secure staking / ` of the roll in a trench, 3"- 5" (75-125mm) deep, dug on contour. Runoff must not be allowed to run under or around roll. NOT TO SCALE 1101111 Itr_. Figure 40 . l4 IllaWill Wades DEPARTMENT OF Revised November 2015 E C 0 , V Please see http://www.ecy.wagov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 St®irwater Management Manual for Western Washington Volume II a Chapter 4 - Page 378 . Inspect the slope after significant storms and repair any areas where wattles are not tightly abutted or water has scoured beneath the wattles. Appmvec9 as Equivalent Ecology has approved products as able to meet the requirements of BMP C235: Wattles. The products did not pass through the Technology Assessment Protocol—Ecology (TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to consideration for local use. The products are available for review on Ecology's website at http://www.ecy.wa.gov- /programs/wq/stormwater/newtech/equivalent.html BMP C236: Vegetative Filtra$o©G Purpose Vegetative Filtration may be used in conjunction with BMP C241: Temporary Sediment Pond (p.388), BMP C206: Level Spreader(p.348) and a pumping system with surface intake to improve turbidity levels of stormwater discharges by filtering through existing vegetation where undisturbed forest floor duff layer or established lawn with thatch layer are present. Vegetative Filtration can also be used to infiltrate dewatering waste from foundations, vaults, and trenches as long as runoff does not occur. Conditions of Use . For every five acre of disturbed soil use one acre of grass field, farm pasture, or wooded area. Reduce or increase this area depending on project size, ground water table height, and other site conditions. . Wetlands shall not be used for filtration. • Do not use this BMP in areas with a high ground water table, or in areas that will have a high seasonal ground water table during the use of this BMP. • This BMP may be less effective on soils that prevent the infiltration of the water, such as hard till. . Using other effective source control measures throughout a construction site will prevent the generation of additional highly turbid water and may reduce the time period or area need for this BMP. . Stop distributing water into the vegetated area if standing water or erosion results. Design Criteria o Find land adjacent to the project that has a vegetated field, preferably a farm field, or wooded area. . If the project site does not contain enough vegetated field area consider obtaining 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 - Page 379 111-3.1.1 Downspout Full Infiltration Systems (SNIP 115.10A) Downspout full infiltration systems are trench or drywell designs intended only for use in infiltrating runoff from roof downspout drains. They are not designed to directly infiltrate runoff from pollutant-generating impervious surfaces. Application Projects subject to 1-2.5.5 Minimum Requirement#5: On-site Stormwater Management (p.55) must provide for individual downspout full infiltration systems or full dispersion if feasible. Evaluate the feasibility, or applicability, of downspout full infiltration unless full dispersion is proposed. Use the evaluation procedure below to determine the feasibility of downspout full infiltration. Runoff Modeling for Roof Downspout Full Infiltration If roof runoff is infiltrated according to the requirements of this section, the roof area may be discounted from the project area used for sizing stormwater facilities. Procedure for Evaluating Feasibility 1. Have one of the following prepare a soils report to determine if soils suitable for infiltration are present on the site: . A professional soil scientist certified by the Soil Science Society of America (or an equivalent national program) . A locally licensed on-site sewage designer . A suitably trained person working under the supervision of a professional engineer, geologist, hydrogeologist, or engineering geologist registered in the State of Washington. The report shall reference a sufficient number of soils logs to establish the type and limits of soils on the project site. The report should at a minimum identify the limits of any outwash type soils (i.e.,those meeting USDA soil texture classes ranging from coarse sand and cobbles to medium sand) versus other soil types and include an inventory of topsoil depth. 2. If the lots or site does not have outwash or loam soils, and full dispersion is not feasible, then consider a rain garden or bioretention BMPs (the next lower priority on-site stormwater management system). 3. Complete additional site-specific testing on lots or sites containing outwash (coarse sand and cobbles to medium sand) and loam type soils. Individual lot or site tests must consist of at least one soils log at the location of the infiltration system, a minimum of 4 feet in depth from the proposed grade and at 2014 Stormwater Management Manual for Western Washington Volume Ili- Chapter 3-Page 452 least 1 foot below the expected bottom elevation of the infiltration trench or dry well. Identify the NRCS series of the soil and the USDA textural class of the soil horizon through the depth of the log, and note any evidence of high ground water level, such as mottling. 4. Downspout infiltration is considered feasible on lots or sites that meet all of the fol- lowing: • 3 feet or more of permeable soil from the proposed final grade to the sea- sonal high ground water table. • At least 1-foot of clearance from the expected bottom elevation of the infilt- ration trench or dry well to the seasonal high ground water table. • The downspout full infiltration system can be designed to meet the minimum design criteria specified below. Design Criteria for Infiltration Trenches Figure III-3.1.2 Typical Downspout Infiltration Trench (p.455)shows a typical downspout infiltration trench system, and Figure III-3.1.3 Alternative Downspout Infiltration Trench System for Coarse Sand and Gravel (p.456) presents an alternative infiltration trench sys- tem for sites with coarse sand and cobble soils. These systems are designed as spe- cified below. General 1. The following minimum lengths (linear feet) per 1,000 square feet of roof area based on soil type may be used for sizing downspout infiltration trenches. Coarse sands and cobbles: 20 LF Medium sand: 30 LF Fine sand, loamy sand: 75 LF Sandy loam: 125 LF Loam: 190 LF 2. Maximum length of trench shall not exceed 100 feet from the inlet sump. 3. Minimum spacing between trench centerlines shall be 6 feet. 4. Filter fabric shall be placed over the drain rock as shown on Figure III-3.1.2 Typical Downspout Infiltration Trench (p.455) prior to backfilling. 5. Infiltration trenches may be placed in fill material if the fill is placed and compacted under the direct supervision of a geotechnical engineer or professional civil 2014 StormwaterManagement Manual for Western Washington Volume III- Chapter 3-Page 453 engineer with geotechnical expertise, and if the measured infiltration rate is at least 8 inches per hour. Trench length in fill must be 60 linear feet per 1,000 square feet of roof area. Infiltration rates can be tested using the methods described in Section 3.3. 6. Infiltration trenches should not be built on slopes steeper than 25% (4:1).A geo- technical analysis and report may be required on slopes over 15 percent or if loc- ated within 200 feet of the top of slope steeper than 40%, or in a landslide hazard area. 7. Trenches may be located under pavement if a small yard drain or catch basin with grate cover is placed at the end of the trench pipe such that overflow would occur out of the catch basin at an elevation at least one foot below that of the pavement, and in a location which can accommodate the overflow without creating a sig- nificant adverse impact to downhill properties or drainage systems. This is inten- ded to prevent saturation of the pavement in the event of system failure. Design Criteria for Infiltration Drywells Figure III-3.1.4 Typical Downspout Infiltration Drywell (p.457) shows a typical downspout infiltration drywell system. These systems are designed as specified below. General 1. Drywell bottoms must be a minimum of 1 foot above seasonal high ground water level or impermeable soil layers. 2. When located in course sands and cobbles, drywells must contain a volume of gravel equal to or greater than 60 cubic feet per 1000 square feet of impervious sur- face served. When located in medium sands, drywells must contain at least 90 cubic feet of gravel per 1,000 square feet of impervious surface served. 3. Drywells must be at least 48 inches in diameter(minimum) and deep enough to contain the gravel amounts specified above for the soil type and impervious sur- face served. 4. Filter fabric (geotextile) must be placed on top of the drain rock and on trench or dry- well sides prior to backfilling. 5. Spacing between drywells must be a minimum of 10 feet. 6. Downspout infiltration drywells must not be built on slopes greater than 25% (4:1). Drywells may not be placed on or above a landslide hazard area or on slopes greater than 15%without evaluation by a professional engineer with geotechnical expertise or a licensed geologist, hydrogeologist, or engineering geologist, and with jurisdiction approval. 2014 Stormwater Management Manual for Western Washington Volume Ill- Chapter 3-Page 454 Figure 111-3.1.2 Typical Downspout Infiltration Trench ,,a 3 • Plan View 4"rigid or 6"flexible roof • perforated pipe drain --- I I i I ` _ sump w/solid lid infiltration trench roof drain f overflow Profile View 4"rigid or 6"flexible splash block perforated pipe CB sump ,----- A w/solid lid 12" t washed rock 1 Yz" �4" ,� - -� r_,;, != --- 1'min -F --- A 1'min fine mesh screen VP varies I- „...„..., 10'min. — — 5'min. -.- Section A-A filter fabric compacted backfill 6" I:I!t5.'•-4 --��jl { •`-III. ice'` 24" 13-®off`= * �=l ief 4"rigid or 6"flexible �� perforated pipe 12" �--e. ��s...o_ 1=i''� elks-a--=.de._,.-, Il • 11.li .ri.Aga /�/i 3 " 11_1,_i1_11_11_11_ washed rock 1 Yz' /a 24" I NOT TO SCALE amen`' Figure III-3.1 .2 Typical Downspout Infiltration Trench DEPARTMENT OF Revised November 2015 ECOLOGY Please see http:J/www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability,and disclaimer. 2014 Stormwater Management Manual for Western Washington Volume Ill- Chapter 3-Page 455 BMP T5.12: Sheet Flow Dispersion Purpose and Definition Sheet flow dispersion is the simplest method of runoff control. This BMP can be used for any impervious or pervious surface that is graded to avoid concentrating flows ). Because flows are already dispersed as they leave the surface, they need only traverse a narrow band of adjacent vegetation for effective attenuation and treatment. Applications and Limitations Use this BMP for flat or moderately sloping (< 15% slope) surfaces such as driveways, sports courts, patios, roofs without gutters, lawns, pastures; or any situation where con- centration of flows can be avoided. Design Guidelines • . See Figure V-5.3.2 Sheet Flow Dispersion for Driveways (p.910)for details for driveways. . Provide a 2-foot-wide transition zone to discourage channeling between the edge of the impervious surface (or building eaves) and the downslope vegetation. This transition zone may consist of an extension of subgrade material (crushed rock), modular pavement, drain rock, or other material acceptable to the Local Plan Approval Authority. . Provide a 10-foot-wide vegetated buffer for up to 20 feet of width of paved or imper- vious surface. Provide an additional 10 feet of vegetated buffer width for each addi- tional 20 feet of impervious surface width or fraction thereof. (For example, if a driveway is 30 feet wide and 60 feet long provide a 20-foot wide by 60-foot long vegetated buffer, with a 2-foot by 60-foot transition zone.) . No erosion or flooding of downstream properties may result. . Runoff discharge toward landslide hazard areas must be evaluated by a geo- technical engineer or a qualified geologist. Do not allow sheet flow on or above slopes greater than 20%, or above erosion hazard areas, without evaluation by a geotechnical engineer or qualified geologist and approval by the Local Plan Approval Authority. . For sites with septic systems, the discharge area must be ten feet downgradient of the drainfield primary and reserve areas (WAC 246-272A-0210). A Local Plan Approval Authority may waive this requirement if site topography clearly prohibits flows from intersecting the drainfield. 2014 Stormwater Management Manual for Western Washington Volume V- Chapter 5-Page 908 Runoff Modeling Where BMP T5.12: Sheet Flow Dispersion is used to disperse runoff into an undisturbed native landscape area or an area that meets BMP T5.13: Post-Construction Soil Quality and Depth (p.911), and the vegetated flow path is 50 feet or more, the impervious area may be modeled as landscaped area. Where the vegetated flowpath is 25 to 50 feet, use of a dispersion trench (see BMP T5.10B: Downspout Dispersion Systems (p.905)) allows modeling the impervious area as 50% impervious/50% landscape. This is done in the WWHM3 on the Mitigation Scenario screen by entering the dispersed impervious area into one of the entry options for dispersal of impervious area runoff. For procedures in WWHM 2012, see Appendix III-C: Washington State Department of Ecology Low Impact Development Flow Modeling Guidance (p.587). 2014 Stormwater Management Manual for Western Washington Volume V- Chapter 5-Page 909 Figure VQ o3.2 gh Uq Filo e i noporsa©U-D '11 fr Peru ow ya Mto p in U >' - . - I I Locate drain 25' from ROW if driveway a, : w:; slopes t ward street. 8 L 'u?:_:`. 700 sq. ft. max. between berms Flu l 1-----"d Driveway :.. 2-4' "Slope; .7""-..\ 1—z1-- 6' min --d-1 ..--„- _ ....,, --... ..,,, . :.; s,-.; r , y'+ , .,,,„,..,..., ,...., ‘, : . .. .,„, air Berm Detail ; ��-..-� ;��=�� '�' Diagonal h;r�� w 25'vegetated berm with 25' flowpath dispersion / trench / 0 Plan Driveway Dispersion Trench Driveway Slope Varies and Slopes Toward Street 1 ‹\ / -c /,' // { `� 7 7 , - Max 2% 4 C?4.4?.ay . .dross`scope itz3,: s.",%-5.-:; ;;:-..:.::zz?......1.-..6„;-‘7::::-.;--, El Plan gab ofea-�. ' Sheet Flow Dispersion from a Driveway 64).�,. : . !; ` Flat to Moderately Sloping Driveways - NOT TO SCALE iliniallM Figure V-5. 3.2 1111.111 Sheet Flow Dispersion for Driveways DEPARTMENT OF Revised January 2016 ECOLOGY Please see http://www.ecy.wa.gov/copyrighthtml for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 5 - Page 910 BMP T5.13: Pori©Consb'acgtaon egn quality and Depth Purpose and Def©nnion Naturally occurring (undisturbed) soil and vegetation provide important stcrmwater func- tions including: water infiltration; nutrient, sediment, and pollutant adsorption; sediment and pollutant biofiltration; water interfiow storage and transmission; and pollutant decom- position. These functions are largely lost when development strips away native soil and vegetation and replaces it with minimal topsoil and sod. Not only are these important stormwater functions lost, but such landscapes themsives become pollution generating pervious surfaces due to increased use of pesticides, fertilizers and other landscaping and householdfindustrial chemicals, the concentration of pet wastes, and pollutants that accompany roadside litter. Establishing soil quality and depth regains greater stormwater functions in the post 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. Appllce ions and Lirtwtations 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, corn- 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 practicable. 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 fill or slope shall, at project completion, demonstrate the following: 1. A topsoil layer with a minimum organic matter content of 10% thy weight in planting beds, and 5% organic matter content in turf areas, and a pH from 6.0 2014 Stonnwater Management Manual for Western Washington Volume V- Chapter 5-Page 911 to 8.0 or matching the pH of the undisturbed soil. The topsoil layer shall have a minimum depth of eight inches except where tree roots limit the depth of incorporation of amendments needed to meet the criteria. Subsoils below the topsoil layer should be scarified at least 4 inches with some incorporation of the upper material to avoid stratified layers, where feasible. 2. Mulch planting beds with 2 inches of organic material 3. Use compost and other materials that meet these organic content require- ments: a. The organic content for"pre-approved"amendment rates can be met only using compost meeting the compost specification for BMP T7.30: Bioretention Cells, Swales, and Planter Boxes (p.959), with the excep- tion that the compost may have up to 35% biosolids or manure. The compost must also have an organic matter content of 40%to 65%, and a carbon to nitrogen ratio below 25:1. The carbon to nitrogen ratio may be as high as 35:1 for plantings com- posed entirely of plants native to the Puget Sound Lowlands region. b. Calculated amendment rates may be met through use of composted material meeting (a.) above; or other organic materials amended to meet the carbon to nitrogen ratio requirements, and not exceeding the contaminant limits identified in Table 220-B, 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 rates based on tests of the soil and amendment. 3. Stockpile existing topsoil during grading, and replace it prior to planting. Stockpiled topsoil must also be amended if needed to meet the organic mat- ter or depth requirements, either at a default"pre-approved"rate or at a cus- tom calculated rate. 4. Import topsoil mix of sufficient organic content and depth to meet the require- ments. 2014 Stormwater Management Manual for Western Washington Volume V- Chapter 5-Page 912 More than one method may be used on different portions of the same site. Soil that already meets the depth and organic matter quality standards, and is not com- pacted, does not need to be amended. Planning/Permitting/Inspection/Verification 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 T5.13 in WDOE Stormwater Management Manual for Western Washington. This document is available at: http://www.soilsforsalmon.org/pdf/Soil BMP Manual.pdf Maintenance . Establish soil quality and depth toward the end of construction and once estab- lished, protect from compaction, such as from large machinery use, and from erosion. . Plant vegetation and mulch the amended soil area after installation. . Leave plant debris or its equivalent on the soil surface to replenish organic matter. . Reduce and adjust, where possible, the use of irrigation, fertilizers, herbicides and pesticides, rather than continuing to implement formerly established practices. Runoff Model Representation 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 T5.10B: 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) . 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' - S' -. l`.{w•ll \ r ♦1 .A Y�,' •• ' • .t\r. 4,:: 1 �) • 4 Sd.. .. r. ?/-'(^. rr n.\ �r .� •• '.�1 1 V;q�tr r. �itl�.• Y`••. a1�y l,,J fl/1 '• r ` r .. h •, . �• :4 i` . '�1^, �� r,t. _ • ,,•wal4 4r >r, 11 t2e . 'Ea#1 y ' i, '; 1 •�w .> n �j , - 14 C. • it / ,.',•4,1. a- AI +iT,\wl M•. : - • '• , "� ° Cl I Al. l� I i �y . .',i"��\„�;�:� , Y.r. v. '. 12f T ..Jrwri,;• 'e:Y•.' i. • .. ` ` • o 1 0 oil 'ILYr,�•itegYt S -•,'1♦ 1 . 6. ; 2.4•421..I '^I1- �,Lr '! • • ' • _ r ' • '^ •�-''r. 'A.1• 1`•t..' 'M y .d, ^ • alb (.1) C (ff 1 M 1 `,� 't!. q:1,*�riE A • it! t,• `4ll ` iY' `1 ' ` f• • ? 1' ( Ny Y ,. A 111(y? 03 IR \. ` f 1 •.(I it , en o co r iv cali O D 0) r m BIM T5.14A: Rain Gardens Purpose and De 'irnitil%n Land development projects may not be of sufficient size such that it is practical to con- struct engineered stormwater facilities for flow reduction and pollutant removal. However, the cumulative impact of smaller development projects on the natural hydro- logy and water quality of local waters can be significant. To reduce that cumulative impact, small projects (see 1-2.4 Applicability of the Minimum Requirements (p.35)) must implement on-site stormwater management BMP's (See 1-2.5.5 Minimum Requirement #5: On-site Stormwater Management(p.55)). Rain gardens are an on-site stormwater management BMP that can provide effective removal of many stormwater pollutants, and provide reductions in stormwater runoff quantity -;nd surface runoff flow rates. Rain gardens are non-engineered, shallow, landscaped depressions with compost- amended soils and adapted plants. The depression ponds and temporarily stores storm- water runoff from adjacent areas. A portion of the influent stormwater passes through the amended soil profile and into the native soil beneath. Stormwater that exceeds the stor- age capacity is designed to overflow to :n adjacent drainage system. Applications and Limitations Rain gardens are an on-site stormwater management BMP option for projects that have to comply with Minimum Requirements#1 -#5, but not Minimum Requirements#6 -#9. For projects electing to use List#1 of 1-2.5.5 Minimum Requirement#5: On-site Storm- water Management(p.55), rain gardens are to be used to the extent feasible for runoff from roofs and other hard surfaces unless a higher priority BMP is feasible. Infeasibility criteria for rain gardens are the same as for bioretention. Please see Biore- tention infeasibility criteria in BMP T7.30: Bioretention Cells, Swales, and Planter Boxes (p.959). Although not required, Ecology recommends installation by a landscaping company with experience in rain garden construction. Rain gardens constructed with imported compost materials should not be used within one-quarter mile of phosphorus-sensitive waterbodies. Preliminary monitoring indicates that new rain gardens can add phosphorus to stormwater. Therefore, they should also not be used with an underdrain when the underdrain water would be routed to a phos- phorus-sensitive receiving water. Desi•in Guidelines Refer to the Rain Garden Handbook for Western Washington (2013) for rain garden spe- cifications and construction guidance. 2014 Stormwater Management Manual for Weste' Washington Volume V- Chapter 5-Page 915 For amending the native soil within the rain garden, Ecology recommends use of com- post that meets the compost specification for bioretrention (see BMP T7.30: Bioretention Cells, Swales, and Planter Boxes (p.959)). Compost that includes biosolids or manures shall not be used. For design on projects subject to 1-2.5.5 Minimum Requirement#5: On-site Stormwater Management(p.55), and choosing to use List#1 of that requirement, rain gardens shall have a horizontally projected surface area below the overflow which is at least 5%of the total impervious surface area draining to it. If lawn/landscape area will also be draining to the rain garden, Ecology recommends that the rain garden's horizontally projected sur- face area below the overflow be increased by 2% of the lawn/landscape area. Underdrains Ecology does not recommend the use of underdrains for rain gardens. Design and con- struction of an underdrain system likely requires professional expertise. Where a muni- cipality intends to require or allow underdrained rain gardens in areas with initial infiltration rates between 0.3 and 0.6 inches per hour, the invert of the underdrain shall be 6 inches above the bottom of the aggregate bedding for the underdrain.A larger dis- tance between the underdrain and the bottom of the aggregate bedding is desirable, but cannot be used to trigger infeasibility due to inadequate vertical separation to the sea- sonal high water table, bedrock, or other impermeable layer. Ecology recommends that the municipality establish standard design specifications and drawings. Maintenance Please refer to the Rain Garden Handbook for Western Washington (2013)for tips on mulching, watering, weeding, pruning, and soil management. The "Western Washington Low Impact Development(LID) Operation and Maintenance (O&M) Guidance Docu- ment" may be consulted for more detailed guidance. BMP T5.14B: Bioretention Purpose and Definition Bioretention areas are shallow landscaped depressions, with a designed soil mix and plants adapted to the local climate and soil moisture conditions, that receive stormwater from a contributing area. Bioretention provides effective removal of many stormwater pollutants by passing storm- water through a soil profile that meets specified characteristics. Bioretention can also reduce stormwater runoff quantity and surface runoff flow rates significantly where the exfiltrate from the design soil is allowed to infiltrate into the surrounding native soils. 2014 Stormwater Management Manual for Western Washington Volume V- Chapter 5-Page 916 \ \ v see CONCRETE \ MIMS \\ EXISTING STORMDRAIN \\\ CURB&GUTTER \\ \ GIS LINE(TYPICAL) LOT 19 \ a \ EXISTING SANITARY PROPOSED \\ \ • \\ - INLET PROTECTION \ SEWER LINE FENCE PER UTILITY \ PER C220,TE IN DOWNN \\ LANDED GENTRY \ (TYPICAL) FENCE PER BMP C103 NEEMEN7 \\ FILTER AECHBASIN LOT 25 \ \ INLET PROTECTION PER \ \ 1 t O AI E S A N D COMMUNITIES \ C220,BLOCK&GRAVEL \ \ FILTER TYPE \ \ \ \ \ PROPOSED \ GENERAL NOTES \ 112.00' CONSTRUCTION PERIMETER \\ OWNER: 170,8 \ 45.68' —� \\ FENCE PER BMP C103 0' 20 33' \ LANDED GENTRY EXIST \ \ BURLiNGTON, WA 504 E. N GRADE \ PROPOSED 4'DIA. LOT LINE \ 189.6 \ SANITARY SEWER \ EXIST 98233 \ GRADE 1—(360)-755-9021 X • \♦ • • • • • • • • • • • • • • • • • • , \ BUILDING: \ PR'POSED4"SC' \ to ,SD • 40 PVC DRAIN LINE \ MAIN FLOOR AREA— 1,632 SF 9.00' • LOWER LEVEL AREA— 1.070 SF ♦ \ � ^ G41141. in ` S ter p5 mi �, �•_ if1? c 1° • ��\ • ER \ TYPICAL \ $ \ CKtNGg. IliyiULCHING TION 0 ZONING: BMp QUAUN AND \ R \ SS 10NN Y1011/ 0%• RIGHT-OF-WAY� it U 1. SETBACKS: Q CHECK DAM PE• BMP 7 ♦ , f0 CSC • LINE ALL SETBACKS IN COMPLIANCE 41 C207:CHECK DA S. ♦• r 0 A tso.. \ WITH CiTY GUIDUNES \• \ (O AS NEEDED. r 5�o1. r $' t ' goa TEMPORARY SIDEYARDS MIN 5' `f • ♦ \ oc, \ / \ 4 CONSTRUCTION REAR YARD MIN 10' ROW ♦ \ COVERED DECK td g�\ \ \ ENTRANCE PER BMP FRONT OF GARAGE TO 0 20' ♦ \ (ABOVE&BELOW) I� Z ".\ \ 111 C105(SIZE TO FIT) ♦ \ 1 . I, \ �o HEIGHT: ♦ \ I a "Q MAX. ALLOWED: 35' ♦ \ i SOILOCATOa ILE o _) �� MAX. ALLOWED: UNDER ♦ \ • Q m K 7 b I (COVER WITI-k _� N ♦ oPARKING: F�LASTIC DURIN ♦ �z. ii : ro . PARKING SPACES PRQViDED= ♦ 1 . I U I STORM EVENTS) \ \� �sr IC \ 2 1N GARAGE, 2 IN DRIVEWAY \ % \ , ♦ \ , \ , -• -1 tf.,:ci;ric ' LOT COVERAGE ♦ \ PORCH ¢ A _LOT 8 ��. � f�♦ \\ oFF MAIN: 189.30 a \ IBUILDING AREA: 2,112 S.F.`', WM PORCH AREA: 120 S.F. ♦ o \ ' ! Lot 18) DECK AREA: 148 SF. J 1,0P. ; \\ FF LL: 179.30 ci h ) :-;7 - •,-La f\\�\ c\ ( ) • TOTAL AREA: 2,380 S.F. PO f ` LOT AREA: 7,781 S.F. S •NO ` ♦ \\ C S\r L A\. ‘? PERCENT COVERAGE: Ou r , � � � SS `{P f ♦ \ _� li l: „ \„ , 2,380 / 7,781 = 30.6X r7o • REE�gP0K •; \\ ,` • •• ,,� 2.o°i°` rf__� �� N; _ :1[.`,�`�_�r; \\ MAXIMUM ALLOWED = 37.5X 11 ` G J -f- ♦ \ O , .L\ 188.90TG �•\�N�, _J\(�� \ \ _) \"` o''. \ IEPg��p1N ` ; \\� ,�. �• )E, )L : t_ a/ \ _ ,9,.7 IMPERVIOUS COVERAGE PROPOSED ♦ ♦ \ o --. , V- / • 4 EXIST BUILDING: 2,112 S.F. PERIMETER SILT ♦ \� " o "' \ --`,t� -1 GRADE m �`=- STEPS/WALKWAY 70 S.F. FENCING(TYP)PER c+ ` t \ a GARAGE gRIVEWAY L \ PORCH: 120 S.F. BMPC233 o LL 4' ot - \ ,�ro DpgE(CK. 1gg48 S.F. \ \ \ \ a f \ • \ FRW. AY 3,$36 S.5 5 ` \ INSTALL 18 LE-OF NDS SPEED CHANNEL DRAIN. • \ \ LOT AREA: - ♦ \ • N 7,781 S.F. ,„ \ ♦ \ \ i' PERCENT COVERAGE' \\ \, - 2.0% I/ • �N\ .- 3,386 / 7,781 = 43.5% LOT LINE& ` �,L '�. NO , .� • \ / MAXIMUM ALLOWED: 48.0% PLAT BOUNDARY f \ oc) �g • m moll \ O �'C` 4:00' Itt 11 \ \ at \ i \ .#5.HiCr% \ _ \ 46.00' ' tag ".."\ 89 �� 14. \ PROPOSED 4•SCH \ f \ INLET 40 PVC DRAIN LINE � �N \ \ C220,B OCK&GRAVER BMp C,21:MCONSIRUCTION .` • 1 i \\ FILTER TYPE i5.13:Pp�m1'AND DEPTH • LOT LINE - Sott aug \ i \ �i `� \ii • CHECK DAMPER BMP i-- , \ Erosion Control Notes for Residential Construction City of Anacortes ` GRAPHIC SCALE •\ C207:CHECK DAMS, \ • �� AS NEEDED. N. 6 0 3 6 12 A. Erosion Control Best Management Practices shall be in place per the accepted site \ �7 �6 \ i� NI 11 plan prior to any construction start. \ • Y 9� i m m - t! B. The erosion control shall be inspected once a day and modified to meet the \ p� / - N. ( IN FEET surrounding conditions as needed. •• Ul N\ C. The storm drain system shall be cleaned daily(Section 7-07.3).All drainage ` \ N i LOT 16 Horiz. Scale: 1 teach = 6 Feet systems shall be cleaned to the acceptance of the City of Anacortes prior to ` \ • �I \� acceptance of the project. ` \\ \'\ r p \ \ 48 NORTH D. Stabilized construction entrances and roads shall be installed at the beginning of X x X i- , construction and maintained during the duration of the project.Additional measures 7 - \, STUART LOWER LEVEL may be required such as wash pads to ensure that all paved areas are kept clean. 173.4 CC-m i �\ N.� `�\ • No mud is allowed to enter onto City streets. EXIST PROPOSED — 0 2-CAR GARAGE LEFT E. Any soils exposed that will not be disturbed for two(2)days during the wet season GRADE PERIMETER CONSTRUCTION - \' N. \ or seven(7)days in the dry season shall be immediately stabilized with the FENCE PER \,, \ ' \ - a _. approved ESC methods(seeding,mulching,plastic covering,etc.) , BMP,C70 i \\ 4 t 1 � " fr-til _. EROSION CONTROL PLAN & F. Two(2)weeks prior to the beginning of the wet season(October 1),all disturbed , i' ,areas shall be reviewed to identify which ones can be seeded in preparation far the ' SITE PLAN winter rains.Disturbed areas shall be seeded within one(1)week of the beginning i es I I of the wet season.A sketch map of those areas to be seeded and those areas to i O� 1 7 \ / I LOT 18 - P133676 remain uncovered shall be submitted to the Project Manager.The Project Manager i'' L \ "+� can require seeding in additional areas in order to protect surface waters,adjacent \ 1 2019 1602 LATITUDE CIRCLE properties or drainage facilities. / �' / \\ \\ N. '� QY O \ ' G. Penalties for an Erosion Control violation are subject to a 630010 61000 fine under / \ C ' / A ANACORTES WA Chapter 17.66-Penalties for Violation. Each day Is considered a different violation. ' ', \ I I �i� V / \ ABBREVIATED LEGAL DESCRIPTION: ^� ��" " DESIGNED:JOB NO: PLAT OF"48 NORTH" LOT 18, 48 NORTH PLAT & PUD, SECTION 22, TOWNSHIP 35 �� \ O DRAWN: NORTH, RANGE 1 EAST, W.M., CITY OF ANACORTES, SKAGIT DATE: 05/03/2019 COUNTY, STATE OF WASHINGTON. '\ SHEET 1 of 2 r OD=MD MEM IIINIMIll IMENIMEMlb IMIIIINIMIIMIO IMIENIMIMIIMID LANDED GENTRY HOMES AND COMMUNITIES I! Ili —, 1 0 (PtLIL' i--. n 7 ri,..:i i7 ,' MAY 1 0 2019 _ e-. F ANAL R-i! '9 o 13th Stil5 ;I Loaric's Sea-Cra(t 0 o‘,.eg.P`j 14th sY rfl 15th St .PC au r' 1t,mSt s Itths[ fb Shannon Point I,1c' 17th Si Y. 0 7c,1`'' 1NIh SI F .Shannon Point 0 Marine Center • �t E�as� „xa$' m 4, l7 5 SITE LOCATION n a) �. i.St h5y a 5 o r c N c t• : 'I�S v +faI `+ i a p \ ii1 -5 <, 1 Tana till a1 c, s • ;: �. i o I� r�BwVzy 7r.oh ;I 04 Is"' Copper Pond � Ship Harbor Inn c ® �v11. . v 44 Cranberry ;} y Lake Park . A , t kye �- s'•ro San Juan Airlines 0 `� • Sum_ci S;eatA�e Sun"9 cs 03 ,1,IJ+— 79thSt a _ her . of St o/!-, to ,? ; .,,,r;�rr 301h SI I— Anacortes z �q�a�ioWay hR� /� Airport a a`*SL', 31st$ 3 m °r m y Sterling�r V-,, n �y a o — 331d" Old Sail's Deli&Market fD y� n ANApp AA II /� V?to to �� z. CORTES3 WA ',OP Skyline Marine Center `, V°�. ^a �1* to d %3 -r; 0 s Ci CZ 6. R• (fii1J.,,1l,i rp4,,,,, `moo C' oreit�sI IDL 48 NORTH Skyline lviurina0 OL rDr �;;,9s 0. ctyaett, STUART LOWER LEVEL Owners Association h ay ,„ a 2-CAR GARAGE LEFT 9�'o0ory, U` 3Go'-'gle EROSION CONTROL PLAN t N. SITE PLAN Map data©2017 Googie 1000 ft LOT 18 - P133676 VICINITY MAP 1602 LATITUDE CIRCLE LOT 18 (P133676) ANACORTES, WA 1602 LATITUDE CIRCLE I JOB NO: PLAT OF"48 NORTH" ANACORTES, WA DESIGNED: LG DRAWN: DATE: 05/06/2019 SHEET 2 of 2 12/31/2018 BMP C160:Certified Erosion and Sediment Control Lead BMP C160: Certified Erosion and Sediment Control Lead f Lo--20i g -c 7c 2 Purpose i&o2 �� , �. e( r FILE COPY The project proponent designates at least one person as the responsible representative in charge of erosion and sediment control (ESC), and water quality protection. The designated person shall be the Certified Erosion and Sediment Control Lead (CESCL) who is responsible for ensuring compliance with all local, state, and federal erosion and sediment control and water quality requirements. Conditions of Use — A CESCL shall be made available on projects one acre or larger that discharge stormwater to surface waters of the state. Sites less than one acre may have a person without CESCL certification conduct inspections; sampling is not required on sites that disturb less than an acre. • The CESCL shall: o Have a current certificate proving attendance in an erosion and sediment control training course that meets the minimum ESC training and certification requirements established by Ecology (see details below). Ecology will-maintain a list of ESC training and certification providers at: http://www.ecy.wa.gov/programs/wq/stormwater/cesCl.html OR o Be a Certified Professional in Erosion and Sediment Control (CPESC); for additional information go to: http://www.envirocertintl.org/cpesc/ Specifications • Certification shall remain valid for three years,. • The CESCL shall have authority to act on behalf of the contractor or developer and shall be available, or on-call, 24 hours per day throughout the period of construction. • The Construction SWPPP shall include the name, telephone number, fax number, and address of the designated CESCL. https://fortress.wa.gov/ecy/madcap/wq/2014SWMM W W interactive/2014%20SWMMW W.htm#TopicsNolumel12014No111%20Ch4%202014Nol II%20Ch... 2/4 12/31/2018 BMP C160:Certified Erosion and Sediment Control Lead • A CESCL may provide inspection and compliance services for multiple construction projects in the same geographic region. Duties and responsibilities of the CESCL shall include, but are not limited to the following: • Maintaining permit file on site at all times which includes the Construction SWPPP and any associated permits and plans. • Directing BMP installation, inspection, maintenance, modification, and removal. • Updating all project drawings and the Construction SWPPP with changes made. • Completing any sampling requirements including reporting results using WebDMR. • Keeping daily logs, and inspection reports. Inspection reports should include: o Inspection date/time. o Weather information; general conditions during inspection and approximate amount of precipitation since the last inspection. o A summary or list of all BMPs implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted: 1. Locations of BMPs inspected. 2. Locations of BMPs that need maintenance. 3. Locations of BMPs that failed to operate as designed or intended. 4. Locations of where additional or different BMPs are required. o Visual monitoring results, including a description of discharged stormwater. The presence of suspended sediment, turbid water, discoloration, and oil sheen shall be noted, as applicable. o Any water quality monitoring performed during inspection. o General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. • Facilitate, participate in, and take corrective actions resulting from inspections performed by outside agencies or the owner. Washington State Department of Ecology 2012 Stormwater Management Manual for Western Washington, as Amended in December 2014 (The 2014 SWMMWW), https://fortress.wa.gov/ecy/madcap/wq/2014SWMMW Winteractive/2014%20SWMM W W.htm#TopicsNolu me112014No1I I%20Ch4%202014No1I I%20Ch... 3/4 Developing a Soil Management Plan — SECTION FIVE Model SOIL IVL. . `1AGFJM NT PLAN for EMI' T5.13 (available as MS Word file at www.SoilsforSalman arg) PROJECT INFORMATION Page # of pages Complete all information on page 1; only site address and permit number on additional .ages. Site Address /Lot No.: Permit Type: Permit Number: Permit Holder: Phone: Mailing Address: Contact Person: Pho,"e: Plan Prepared By: ATTACHMENTS REQUIRED (Check off required 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 SCARCFICATION 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 METRO'I'RO 11: X 3.1 (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 --> --> --> 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 & 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. MITL,CH ,000 sq.ft. PRODUCT: X 6.2 (conversion, to give 2 inch mulch depth) = cubic yards of mulch —> — — —p —p — QUANTITY: CU. YDS. TOTAL AMENDMENT/TOPSOIL/MULCH FOR ALL AREAS (complete on page I only totaling all areas/pages in this Plan) D Product#1: 1 Quantity: cu. yds. D Test Results: % organic matter C:N ratio <25:1 (except mulch, or <35:1 for native plants) "stable" (yes/no) © Product #2: El Quantity: cu. yds. D Test Results: % organic matter C:N ratio <25:1 (except mulch, or <35:1 for native plants) "stable" (yes/no) C Product #3: El Quantity: cu. yds. D Test Results: %rganic matter _C:N ratio <25:1 (except mulch, or <35:1 for native plants) ___ "stable" (yes/no)_ Date: Inspector: Approved: Revisions Required: Date: Inspector: Approved: Revisions Required: COMMENTS: '13 a.gov/ecy/madcahttps://fortress.wp/wq/2019SWMMW WPrel i m Draft/Content/To pics/Volumel l/ConstructionStormwaterBMPs/ConstructionSourceControlBMPs /BMPc154.htm r pirviy BMP C154: Concrete Washout Area Purpose Preventor re uce e •isc arge o po ut —ts F'rom concrete waste to stormwateT bi conducting washout off-site, or performing on-site washout in a designated area. Conditions of Use Concrete washout areas are implemented on construction projects where: • Concrete is used as a construction material • It is not possible to dispose of afl-concrete wastewater and washout off-site (ready mix plant, etc.). • Large concrete handling equipment, such as concrete trucks, chutes, pumps, or other concrete coated equipment are washed on-site. Note that small concrete handling equipment, such as hand tools, screeds, shovels, rakes, floats, trowels, and wheelbarrows may be washed into formed areas awaiting concrete pour. At no time shall concrete handling equipment be washed off into the footprint of a proposed infiltration BMP. Design and Installation Specifications Implementation • Perform washout of concrete trucks.at an approved off-site location 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 allow excess concrete to be dumped on-site, except in designated concrete washout areas. • Concrete washout areas may be prefabricated concrete washout containers, or self-installed structures (above-grade or below-grade). • Prefabricated containers are most resistant to damage and protect against spills and leaks. Companies may offer delivery service and provide regular maintenance and disposal of solid and liquid waste. • If self-installed concrete washout areas are used, below-grade structures are preferred over above-grade structures because they are less prone to spills and leaks. • Self-installed above-grade structures should only be used if excavation is not practical. • Concrete washout areas shall be constructed and maintained in sufficient quantity and size to contain all liquid and concrete waste generated by washout operations. Education • Discuss the concrete management techniques described in this BMP with the ready-mix concrete supplier before any deliveries are made. • Educate employees and subcontractors on the concrete waste management techniques described in this BMP. • Arrange for the contractor's superintendent or Certified Erosion and Sediment Control Lead (CESCL) to oversee and enforce concrete waste management procedures. • A sign should be installed adjacent to each concrete washout area to inform concrete equipment operators to utilize the proper facilities. Contracts Incorporate requirements for concrete waste management into concrete supplier and subcontractor agreements. Location and Placement • Locate concrete washout areas at least 50 feet from sensitive areas such as storm drains, open ditches, water bodies, or wetlands. • access e comer oo .s, preferably near the area where-the concrete is being poured. • If trucks need to leave a paved area to access the concrete washout area, prevent track-out with a pad of rock or quarry sp.alls (see BMP C105: Stabilized Construction Entrance / Exit). These areas should be far enough away from other construction traffic to reduce the likelihood of accidental damage and spills. • The number of concrete washout areas you install should depend on the expected demand for storage capacity. • On large sites with extensive concrete work, concrete washout areas should be placed in multiple locations for ease of use by concrete truck drivers. Concrete Truck Washout Procedures • Washout of concrete trucks shall be performed in designated concrete washout areas only. • Concrete washout from concrete pumper bins can be washed into concrete pumper trucks and discharged into designated concrete washout areas or properly disposed of off-site. Concrete Washout Area Installation • Concrete washout areas should be constructed as shown in the figures below, with a recommended minimum length and minimum width of 10 ft, but with sufficient quantity and volume to contain all liquid and concrete waste generated by washout operations. • Plastic lining material should be a minimum of 10 mil polyethylene sheeting and should be free of holes, tears, or other defects that compromise the impermeability of the material. • Lath and flagging should be commercial type. • Liner seams shall be installed in accordance with manufacturers' recommendations. • Soil base shall be prepared free of rocks or other debris that may cause tears or holes in the plastic lining material. Maintenance Standards Inspection and Maintenance • Inspect and verify that concrete washout areas are in place prior to the commencement of concrete work. • Once concrete wastes are washed into the designated washout area and allowed to harden, the concrete should be broken up, removed, and disposed of per applicable solid waste regulations. Dispose of hardened concrete on a regular basis. • During periods of concrete work, inspect the concrete washout areas daily to verify continued performance. - o Check overall condition and performance. o Check remaining capacity (% full). o If using self-installed concrete washout areas, verify plastic liners are intact and sidewalls are not damaged. o If using prefabricated containers, check for leaks. • Maintain the concrete washout areas to provide adequate holding capacity with a minimum freeboard of 12 inches. • Concrete washout areas must be cleaned, or new concrete washout areas must be constructed and ready for use once the concrete washout area is 75% full. • If the concrete washout area is nearing capacity, vacuum and dispose of the waste material in an approved manner. o Do not discharge liquid or slurry to waterways, storm drains or directly onto ground. o Do not disc.' arge to the sanitary sewer without local app oval. o Place a secure, non-collapsing, non-water collecting cover over the concrete washout area prior to predicted wet weather to prevent accumulation and overflow of precipitation. o Remove and dispose of hardened concrete and return the structure to a functional condition. Concrete may be reused on-site or hauled away for disposal or recycling. • When you remove materials from a self-installed concrete washout area, build a new structure; or, if the previous structure is still intact, inspect for signs of weakening or damage, and make any necessary repairs. Re-line the structure with new plastic after each cleaning. Removal of Concrete Washout Areas • When concrete washout areas are no longer required for the work, the hardened concrete, slurries and liquids shall be removed and properly disposed of. • Materials used to construct concrete washout areas shall be removed from the site of the work and disposed of or recycled. • Holes, depressions or other ground disturbance caused by the removal of the concrete washout areas shall be backfilled, repaired, and stabilized to prevent erosion. Figure 11-3.7: Concrete Washout Area with Wood Planks ts pdf download Figure 11-3.8: Concrete Washout Area with Straw Bales pdf download •• Figure 11-3.9: Prefabricated Concrete Washout Container w/Ramp pdf download Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington 3m Minimum - o - o 0 o Lath and flagging \ \ ( ) = ( ) , on 3 sides / O Sandbag 0 .___, >____ o Berm Sandbag .� 10 mil plastic lining Varies O A O A o _Th � o ��*./6,71' 1m _< 0 // \ � Berm t, / /\ /\ \___n o -\ = 0 - 0 Section A-A 10 mil plastic lining Plan Notes: 1. Actual layout determined in the'fieid. Type "Below Grade" 2. A concrete washout sign shall be installed within 10 m of the 3m Minimum ► temporary concrete washout facility. RI 61 ' m IV Wood frame B B securely fastened around entire perimeter with two Ill stakes �' Varies 10 mil FA plastic lining E ® \-- Stake (typ.) rg m Section B-B 10 mil plastic lining Two-stacked 2x12 rough Plan wood frame Type "Above Grade" with Wood Planks NOT TO SCALE r llia. . Concrete Washout Area with Wood Planks 14. 11 Revised June 2016 DEPARTMENT OF ECOLOGYPlease see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 7 Straw bale 10 mil plastic lining Binding wire Staples Native material (2 per bale) 11 (optional) ((�� Wood or 1.1 it Plywood metal stakes 11R:. =ui. 1200 mm 610\ice:_.__ _._.�1� x mm Wood post (2 per bale) 1 1 painted white (89 mm x 89 mm Lag screws x 2.4 m) Section B-B (12.5 mm) coNc el Black letters WASHOUT I 150 mm height II 915 mm '_I I I915mm f 3m Minimum Concrete Washout Sign Stake (typ) Detail (or equivalent) ■ ■ - • B B I ■ ■ I Varies --0.-1 1-01-- 50 mm 200 mm ^`� 3.05 mm dia.• t i steel wire ■ ■ Staple Detail Straw bale1 10 mil plastic lining Notes: 1. Actual layout (typ.) determined in the field. Plan 2. The concrete washout sign shall be installed within 10 m of the temporary concrete washout facility. 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