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Home My WebLink AboutStorm Water 1-5 BLD-2018-0039 1410 Latitude Circle 4 Planning, C m a�noty, & E( .enormoo Devrelopmer t Department Po Box 547, Anacorlo , WA 98221 PH: 380.290.1941 �4, , � 13 i r isofS PPP �. (Conateuctio n Sao:wow I.v P©lk © 5-nivengon Man) Please check off bates t,0 show that each ele-rment has been read and understood.Provide details where applicable and if certain aspects ere aMnecessary;or exempt,clearly justify.Details of the 13 Elements and the correlating 4,NiPs are listed on Pg‘ 236 of the 2014 St:..r r meter ianegement Manual for Western Washington i'S ,iViMWW).A link is provided on the City of Anacortes website,under Planning, Community,St Ec0 nomic Development ilepartment,as well as under Storrriweter on the Engineering Division of Public Work's page. Owner flame: 416 A4;Q74 .4,,lA C eve./--F f l L C'_ �GL- Site Address: / f 0 a j I/ 4 ae ?" , / 1 Prepared By: Zi4Aiye ,ir f/ve l The Stormwater checklist or building permit determined that: ❑ The 13 elements must be addressed ff•r 0 These elements must be addressed for ccnstrmction activity adding under 2,�1 z® construction activity adding 2,0 i;0';sq.ft. sq.ft.zff hard surface area. itr more of hard surface area. This means that an attached narrative and site plan ere required with this document. Under each element,_eupioOn the best man@ 7e me t prm 31Qea MIN) used orjusti ream*7 for those that will n.t he wed. If needed. °fusee attach a narrative to fftortha 'c eat' xW t Il�-' i tv 44 L / , i t ELM/3lfl 341: Preserve Vegetation/Mark Clearing Limits 0 Before beginning lend disturbing activities, including clearing and grading,clearly marls ail clearing limits,sensitive areas and their buffers,and trees that are to be presented within the construction area. ❑ Retain the duff layer, native Up soil,end natural vegetetiz:n in an undisturbed state to the maximum degree practical. Page 1off3 arch,2017 ERAENT 2e Estabkakh C*nstracttaon Access O Limit c©nstrruc i n vehicle access and mat to one r.,ute, W possible. O Stabilize access points with a pad of quarry spells,crushed rock, •r other equivalent SMPs,t > minimize tracking:into roads. ❑ Locate wheel Wash or tare baths on site, if the stabilized construction entrance as not effective an preventing tr eking sediment onto reads. ❑ Bff sediment as tracked off site,dean the affected roadway(thoroughly at the end of each day,or more frequently as necessary(eye wet weather). Remove sediment trim roads by th.;velang, sweeping,or pack up and tr. nsport the sediment to a controlled sediment disposal area. O Conduct street washing only after sediment is removed an accordance with the above bullet. O Control street wash wastewater by pumping back on site or •tharwasa preventing at from discharging into systems tributary waters of the State. ELEMENT 3:C,•'ntrol Now[dates ❑ Protect properties and waterways downstream of development sates from erosion and the associated discharge of turbid waters due to increases in the velocity and peak volemetrac flew rate of stormwater runoff from the project sate, ❑ Where necessanr to comply with the bullet above,construct stormwater retention or detention facilities as one of the first steps an grading.Assure that detention facilities function Properly before constructing site ampr•veement(e.g.impervious surfaces). ❑ Of permanent infiltration ip nds are used for flow contrel during construction,protect these facilities ffrOm siltation during the construction phase. ELErrIa T 4: lnata00 Sediment Cruntroas D Design,install,and maintain effective elision controls and sediment controls to minimize the discharge of pollutants. ❑ Construct sediment control SiviPs(sadament ponds,traps, filters,etc.)as one of the first steps in grading.These bMPs shall be functional before other Band disturbing activities take place. O Minimize sediment discharges from the site.The design, installation and maintenance of erosion and sediment controls must address factors such as the amount,frequency,intensity and duration of precipitation, the nature of resulting stormwater runoff,and goal characteristics, including the range of soil particle sizes attpected to be present on the site. D 'l irect stormwater runoff from disturbed areas through a sediment pot nd or other appropriate sediment removal BMP, before the runoff leaves a construction site or before discharge to an Page 2 of f March,2017 infiltration facility.Runoff from fully stabilized areas maybe discharged without a sediment removal BMP,but must;met the flow control performance standard in Element U3,bullet#1. ❑ Locate l MPs intended to trap sediment ron-site in a manner to avr„ad interference with Me movement of juvenile salmonids attetroptinjg to enter off-channel areas or drainages. ❑ Provide and maintain nature@ buffers around surface waters,direct st•'rumwater to vegetated areas to increase sedirnent removal,and maximise sto rmi ater infiltration. ❑ Where feasible,design outlet structures that .t-ithdraw impounded storrnwater from the surface $ av•id discharging sediment that is still suspended lower in the water c;lumn. L 6 T 5: Stabilize Soils D Stabilize exposed and unworked soils by application of effective BMPs that prevent erosion. Applicable 8r I Ps include, but are not limited t•:temporary and permanent seeding,sodding, mulching,plastic covering,er•,sion control fabrics and matting,soil application of polyacrylar, ide(PAM),the early application::f gravel base early on areas to be paved,and dust control. ❑ C.ntrrol stormwater vrimme and velocity within the site t,.; minimize soil erosion. ❑ Control stormwater discharges, including both peak flow rates and total stormwater volume, to minimize erosion at outlets and to minimise downstream channel and stream bank erosi.n. ❑ Soils must not remain exposed and unworiced for mire 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 ❑ Stabilise soils at the end of the shift before a holiday or weekend if needed based on the weather forecast ❑ Stabilize soil stockpiles from emit-n,protect with sediment trapping measures,and where possible,be located away from storm drain inlets,waterways,and drainage channels. ❑ rr inimize the amount of soil exposed during construction activity. ❑ Minimise the disturbance of steep slopes. ❑ Minimise soil compaction and,unless infeasible,preserve topsoil. EL r f ENT 5: Protect Slopes ❑ Design and construct cuteand-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 3 March, 2017 O Divert of site stormwater frun-on)®r ground water away from slopes and disturbed areas with interceptor dukes,pipes,and/o;r swaies, ff-site stormwater should be managed separately from stormwater generated on the site. ❑ At the top of sl o pas,co lied drainage in pipe slop drains or protected channels to present erosion. o °Temp:srary pipe slope drains --lust handle the peak volumetric flow rate calculated using a W minute time step from a Type 1A,1O year,24 hour frequency storm for the developed conditi on.Alternatively,the 10-year, 1-hourr, flow rate pred6ctedjbndicated by an approved continuous runoff model,increased by a facto r of 16, may be used.The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest f>'iDens rates. if using the Western Washington HydroloYe Model g45.'MIK to predict flows,bare soli areas should be modeled as "landscaped"area. o ;'here 1S- ,inute time steps are mailable in an approved continuous runoff model,they may be used directly without e correction fact r. ❑ 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. ❑ Stabilise soils on slopes,as specified in[Element S. ❑ [8MP combinations are the most effective method of protecting slopes with disturbed soils.Ex: Use both mulching and straw erosio,n ci ntr blanker,o ELEMENT I T 7 Protect Drain inlets ❑ Protect all storm drain inlets made operable during construction so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment, ❑ Clean or remove and replace inlet protection devices when sediment has filled one-third of the available storage(unless a different standard is specified by the product manufacturer). O Where possible,protect ail existing;storm drain islets so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. O Keep all approach roads glean. ©o 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 8 March, 2017 ELEMENT 0:Stabilize Channels and;,cutlets ❑ Design,ct_nstruct,and stabilize all on-site conveyance channels to prevent erosion from the ffolliiwing expected peak flows: o ;'Channels must handle same peak v®luametric flow rate as temporary pipe sit pe drains listed hi Element 6,above. ❑ provide stabilization,including arm wring material,adequate to prevent erosion of outlets, adjacent strearribanks,slopes,and downstream reaches at the Ce%utlets of ail conveyance systems. 0 The best method f r stabilizing channels is ti completely line the channel with a[blanket product first,then add check darns as necessary to fun- lin as an anchor and to slow the fl w of water. ELEMENT Ph Control Polkut.,Ms ❑ Design, install,implement,and maintain effective pollution prevention measures to rroinimize the discharge of pollutants. O Handle and dispose a all p•ilutants, including waste materials and demolition debris that occur on-site in a manner that does n•t cause contamination of storrnwater. ❑ Provide cover,containment,and protectic®n from vandalism for all chemicals,liquid products, petroleum products,and other materials that have the p•tential 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 larcest tank within the containment structure.Double-walled tanks do nit require additional secondary containment. D Conduct maintenance,fueling,and repair of heavy equipment and vehicles using spill prevention and control measures.Clean contaminated surfaces immediately following any spill incident. 0 Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water,such as closed-loop recirculation or upland land application,or to the sanitary sewer,with local sewer district approval.Wheel wash or tire bath wastewater should not include wastewater from concrete washout areas. 0 Apply fertilizers and pesticides in a manner and at application rates that will not result in loss of chemical storrmwater runoff. F;:,llow manufacturers'label requirements for application rates and procedures. ❑ Use gMps to prevent contamination of stormviater 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 .aters, waste streams generated from concrete grinding and sawing,exposed aggregate processes,dewatering concrete vaults,concrete pumping,and mixer washout waters.Adjust the pH if stormwater if necessar;'to prevent violations of the water quality standards. Page 3 of 3 arch,2017 ❑ MOM that washout tf c ncretee trucks is peeftrmed off-site or ina designated concrete washout areas only.Do not wash out concrete trucks onto the gr;'und,or Intl;storm drains,open ditches, streets,or streams. Do not dump excess concrete on site, except in designated concrete washout areas.Concrete spillat.e or concrete discher e to surface waters t f the State is prohibited. ?o not use upland Band applications for discharging wastewater from concrete washout areas. ❑ Obtain written apv•val from Ecol tt y,and provide to the City before wing chemical treaty !ent other than C12 or d.,r,ice to adjust pH. ❑ Woody debris may be chopped and spread on she. ❑ Conduct oil changes,hydraulic system drain down,solvent and de-greasing cleaning operations, el tank drain down and removal,and other activities hitch may result in discharge or spillage of pollutants to the ground or Intl st trmwater rangy,fff using spill prevention:7leasures,such as drip pans. ❑ Clean contaminated surfaces immediately following any discharge •r spill incident.Emergency repairs may be performed on-site using temporary plastic placed beneath and, if raining,over the vehicle. EO EMEGIT i©e Control Ode-Watering ❑ Discharge fftundation,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. D Discharge clean,non-turbid de-watering water,such as well-point ground water,to syster,s tributary to,or directly into suilace waters of the State,as specified in Element 8,provided the de-watering flow does not cause erosion t,r flooding of receiving waters or interfere with the operation of the system. Do not route clean dewatering water through stormwater sediment ponds. Mote that"surface waters c f the State"may exist on a construction she as well as off site;for example,a creek running through a site. O Handle highly turbid or contaminated dewatering .ater separately from stormwater. ❑ ether 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 w r other suitable treatment technologies. 4. Sanitary or combined sewer discharve with local sewer district approval,if there is no other option. S. Use of a sedimentation bag with outfall to a ditch or swage for small volumes of ltcaIized dewatering. ❑ Construction equipment operation,clamshell dirking,concrete tremie pour,or work inside a cofferdam can create highly turbid or contaminated dewatering water. ❑ Discharging sediment-laden(r,;uddy)water into waters of the State likely constitutes a violation Page 5 of C '.arch,2017 of water quality standards for turbidity.The easiest way to avoid discharging muddy water is through infiltration and preserving vegetation. ELEMENT aa,o Maintain Ps ❑ Maintain and repair all temporary and permanent erosion and sediment control 91Ws as needed to assure continued performance of their intended function in accordance with St<M P specifications. 0 Remove all temporary erosion and sediment control l MPs within 30 days after achieving final site stabilization or after the ter porar MPs are no longer needed.Some temporary erosion and sediment co-ntrrol BMPs are bin-degradable and designed to re ain in place following construction such as composts city, 0 Provide protection t•,ail SW Ps installed fir the permanent control of stormwater from sediment and compaction.MI Br.Ps that are to remain in place following completion of construction shall be examined and placed in full operating conditions. if sediment enters the EIMPs during construction,it shall be removed and the ffaciiit"shall be returned to the conditions specified in the construction documents. 0 Remove or stabilize trapped sediment •n site. Permanently stabilize disturbed soil resulting from removal of BMPs or vegetation. ELEMENT 21 Manage the Project—Projects subject to Minimum Requirements 2-9 must have a Certified Erosion and Sediment Control Lead (CESCL) for site inspections. Projects subject to Minimum Requirements 1 55 do not require the inspector to be certified. By the initiation of construction,the SY%PPP must Identify the CESCL or inspector,who shall be present on-site or on-call at all times. Management details starting on 4';; 0 Phase development projects to the maximum degree practicable and take into account seasonal works limits to prevent soil erosion and prevent transporting sediment from the site during construction. ❑ inspection and monitoring o Inspect,maintain, and repair all SiViPs as needed to assure continued performance of their intended function. O Maintain, update,and implement the S'..-PPP. ❑ Clearing and grading activities for developments shall be permitted only if conducted using an approved site development plan(e.g.,subdivision approvalj. O From Oct 1 through Apr 30,clearing,grading,and other soil disturbing activities is permitted only if shown that the site operator will prevent silt-laden runoff from leaving the site through a combination of the following: Page 7 of 3 r=�arch, 2017 1. Site conditions including existing vegetative coverage,slope,soil type,and proximity to receiving waters. 2. Lima activities and the extent(f disturbed areas. 3. Proposed erosion and sediment control measures, either conditions]can oaafirserace the seasonal limitation,sin site disturbance.The City of Ara i cortex has the authority t* take enforcement action per X C 19.76$t®rmwatei. ❑ The following activities are exempt from the seasonal clearing and grading limitations: 1. Routine maintenance and necessary repair •f erosi•n and sediment control B'.,'Ps; 2. Routine maintenance of public facilities or existing utility structures that do not expose the sill or result in the removal cfil the vegetative cover to soul 3. Activities where there is WWO%infiltratiwn of surface , ater runoff within the site an approved and installed er•slon and sediment ointril facilities. ELEMENT 13e Prated Lew l coact DevMopmewn 8"v1PS 0 if lmple;nenting any hloretentli n facilities a r rein gardens,see �:, for requirennents. T mil'' 7/g.c)/ 5 Applicant Signature l D e 1 ! , Pak:e8off8 March, 2017 EXHIBIT "B" 1410 LATITUDE CIRCLE LOT 4, PLAT OF 48 NORTH P133662 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 BM Ps described in ELEMENT 4, below will reduce velocity of flows. ELEMENT 4: Install Sediment Controls The following BMPs are proposed as temporary sediment controls: 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 proposed 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 from 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 proposed 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 C122: Nets and Blankets Nets and Blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so vegetation can become well established. 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. E HOCBOT"C" 00 LATOU JL)LIME LOT 4D PLAT OF 40NO0RTH P133662 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 ll- 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 ll- 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 Figure 11-4.1.1 Stabilized Construction Entrance NOT TO SCALE ckoad /I/. // �'�� 1, 1_ _�� 100'min. 1000.0, Install driveway .4111�1�1.� culvert if there is a roadside ditch present • ��.1l1�1�1�-r 4"-8"quarry +— `— `Z `r�;!` `t-�• spells •1.1.1.1.1 11*1*104p..1*1*1111,, •�•I�I�I�I�I�� Geotextile .rY ; ;• 1111 15'min. Notes: \ / 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 ingress/egress crowned so that runoff area drains off the pad. Figure 11-4.1 .1 gliiiiiii Stabilized Construction Entrance DEPARTMENT OF Revised June 2015 ECOLOGY Please see http://www.ecy.wa.gov/copyright.htm/for copyright notice including permissions, State of Washington limitation of liability,and disclaimer. 2014 Stormwater Management Manual for Western Washington Volume ll- Chapter 4 -Page 273 Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C105: 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/equ ivalent.html SNIP 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 C105: 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 11-4.1.2 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 ll- 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:1V, 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 C120: 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/sormwater/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 II-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 3/4" sieve openings 70% Minimum Percent passing '/4" 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 11- Chapter 4 -Page 285 or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remulched. Table 11-4.1.8 Mulch Standards and Guidelines Mulch Quality Application Material Standards Rates Remarks 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 tackifier, or covering with netting. Blown straw undesirable 5 bales per always has to be held in place with a tackifier as Straw seed and 1,000 sf or 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 Fibers should be kept to less than 3/4 inch. per acre 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 11- Chapter 4-Page 286 Table 11-4.1.8 Mulch Standards and Guidelines (continued) Mulch Quality Application Remarks Material Standards Rates 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 Veget- from fines 2" thick because of its tendency to be transported by run- to 6 inches min.; off. It is not recommended within 200 feet of sur- ation in length for face waters. If seeding is expected shortly after texture, van- 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 chased min.; Wood- from a su approx. 100 matter in the soil. Special caution is advised based p pp regarding the source and composition of wood- Mulch or plier with a tons per based mulches. Its preparation typically does not Wood Solid acre provide any weed seed control, so evidence of Straw Waste (approx. residual vegetation in its composition or known Handling 800 lbs. per inclusion of weed plants or seeds should be mon- Permit or cubic yard) itored and prevented (or minimized). one exempt 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 ll- Chapter 4 -Page 287 Table 11-4.1.8 Mulch Standards and Guidelines (continued) Mulch Quality Application Remarks Material Standards Rates high length- to-width ratio. BMP 1 2 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 11- Chapter 4 - Page 288 Table II-4 1. Mulch Standards and Guidelines (continued) Mulch Quality Application Remarks Material Standards Rates high length- to-width ratio. RIVIP C122: Nets an 0 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: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: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 ll- Chapter 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, cost, and availability. Design and Installation Specifications • See Figure II-4.1.3 Channel Installation (p.292) and Figure II-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 hydromulch 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- D7A8556CC D57/0/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 ll- Chapter 4 -Page 290 • Repair and staple any areas of the net or blanket that are damaged or not in close contact with the ground. . Fix and protect eroded areas if erosion occurs due to poorly controlled drainage. 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4-Page 291 Figure 11-4.1.3 Channel Installation NOT TO SCALE ...,,..,5,14,•i. ..,::::;.';.:-,C,:.;',",i--.'7/-V ,.:.,....„ , ..........r. \/ li / / / / / \/ / / / Ii /�/%//\\/ s \ \/\ \s LONGITUDINAL ANCHOR TRENCH TERMINAL SLOPE AND CHANNEL ANCHOR TRENCH TAKE AT 3'-5' ilF P `/111 / 'ir' INTERVALS. \ S '1.'."'.':!..::�r P P r �Et P P .%r a : 4 ` GHPT(0� r r / P / ry ///// CHECK SLOT AT 25' INTERVALS r ///\ ' ISOMETRIC VIEW /7 / ... .... itli111: -* .. 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. IMAM Figure 11-4.1 .3 Viii Channel Installation DEPARTMENT OF Revised June2015 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 II- Chapter 4-Page 292 Pitquirc {id A Z_i{). [ ® _ 1 lmiI_vJr r.f n Anchor in 6" x 6" min. trench and staple at 12" intervals �� '.".. r fir.-.' �. ~r i • :`I-. Min. 2" overlap .C�JI=11=1 `- •11-11-11= I!: '111=:111CIr 3 •f; `;-...;.. : Min. 6" overlap _ i 1.:1.T ,:�� 7Y V a-- 1ti"11.-15-11—{1=11`-{{DIY ��.�1.. -11=II��i- Staple overlaps 41.— -11:W 11..-11 u-1Ll-�--1� Y — — — 111111.=11.-IL11:11;f°;f1:11:114.4.I'-01 11=11.'1112 N f1" ",�';'fF—iktII 11:n- 11.-11.11�11=11 11 11:-11.-11.-11: 1!=11-1f.—II— max. 5" spacing 11=1 11=11-11=11.=11=11=1.=1I=1 .11.=11i 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 blanketsfmattings 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 Figure ft=4. 1 . J Slope nsta aflon Revised June 2015 DEPARTMENT OF ECOLOGY Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Storrnwater Management Manual for Western Washington Volume ll - Chapter 4 - Page 293 13 P 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 MP 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 for a 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 II- Chapter 4 -Page 296 Maintenance 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 establish 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 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. 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 II- Chapter 4 -Page 297 Maintenance 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 establish 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. i , 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 com- 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. 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 ll- 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. • 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. o 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. . 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 least 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: . Side slopes of the stockpile shall not exceed 2H:1V. . Between October 1 and April 30: 2014 Stormwater Management Manual for Western Washington Volume II- 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 C105: 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 P C2O7: 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 11- 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:1V 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. Maintenance 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 ll- Chapter 4 -Page 353 J [Id-4 ,2 c L'A ©['r7, Dal View Looking Upstream A 18„ 12" (0.5m) (150mm) it „ • -c\' /-\'/// 4"0. A •d Q •c °/.%j;/24" (0.6m) Note: •o:P Key stone into channel banks and extend it \'/ / /• / beyond the abutments a minimum of 18" (0.5m) to prevent flow around dam. A Section A-A Flow 24" (0.6m) e /! �° op0.0 �6D eo ..\///V/•) • \ / ./A 8' (2.4m) Spacing Between Check D - ms 'L' = the distance such that points 'A' and 'B' are of equal elevation. • Point'A' Point'B' tvo VVM NOT TO SCALE Figure II-4•2i 111=0111 Rock Check Darn DEPARTMENT OF Revised July 2015 ECOLOGY Please see http://www.ecy.wa.gov/copyrrght.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 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 ouffalls 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 II- 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 Emergency Applicable for Protection OverflowPaved/Earthen Conditions of Use Surfaces Drop Inlet Protection Excavated drop Yes, tern- Applicable for heavy flows. Easy inlet protection porary flood- Earthen to maintain. Large area Require- ing will occur ment: 30'x30'/acre Block and gravel drop inlet Yes Paved or Earthen Applicable for heavy concentrated 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- Small capacity Used for sturdy, more compact tection with overflow Paved installation. wooden weir Block and gravel curb inlet Yes Paved Sturdy, but limited filtration. protection Culvert Inlet Protection Culvert inlet Sed- 18 month expected life. invent 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:1V. . 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 '/z-inch openings over all block openings. . Place gravel just below the top of blocks on slopes of 2H:1V 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 a1-foot wide level stone area between the structure and the inlet. . Use inlet slope stones 3 inches in diameter or larger. . Use gravel '/2-to 3/-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 F ri ua LILY _obi o L o c 3 I',3 k c h uf L d ` [r Yes'_ A{J ar .-A Drain grate c.",,Pg,b•CY4`51e„q›.4-,a. , 6. IA. •p q c 0 a) . A, -if-- ,06emea, p e Concrete block ) Cao a .o o�yo .p:? 0 °U°0•/ .>,.. , boa �• ,• JI 4Li •0, O o a • V °o ^ ~ A `�`�c o Gravel backfill oir..t�:y s _ {I- V. /�a Y G M'52 - t] 1 'CR61413 's,--,)-(1-;42. <, .., .A9,4 « OCtrc .,,5n0*a�•O UR JR700� C� 4 �� 510� . �.,,oC .oCi'• ," roc Plan View Concrete block Wire screen or Gravel backfill ��Overflow filter fabric water ' P�onding height —1 a,?-ps r ----- - Water a(¢�\( a ,j Qti n ////\�.///\// // //\,l///�, Dropinlet %//\/\//\//��`/.Y, 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 66611113111 Figure 4 2, °VW° Mick and Gravel Fifter DEPARTMENT OF Revised August 2015 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 - 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 '/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 1/2-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 11-4.2.9 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 '/2-inch 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 11-4.2.10 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/prog rams/wq/stormwater/newtech/eq uivalent.html 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4 -Page 362 : tmtr o ch 2ndi C yr° v o_ ©m'< LotrO®©ul© A � Catch basin Back of sidewalk 2x4 Wood stud Back of curb Curb inlet Concrete block fi ate . :; ' '?; si Wire screen or c' o ' pia eo a ' c N. 6 filter fabric 'v " � p-o•P� �yQti �V.0 � a o ate, a .,a o do * c inch (20 mm) A Concrete block Drain gravel Plan View Ponding height 3/4 inch (20 mm) Drain gravel Overflow . t Ram„ {: {: Curb inlet „vi: . Wire screen or NY/%2%7' filter fabric 2x4 Wood stud ��' �� !� �� (100x50 Timber stud) • Catch basin Concrete block Section A-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 Figure lV=4.2. 9 411Wal Block and Gravel Curb Inlet Protection DEPARTMENT OF Revised August 2015 E C 0 !11 G Y 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 ll - Chapter 4 - Page 363 ii= Ilco G�i[r'C UDEA.2,3i G ©uitit 7[1-DCl Ou'Re r' in6il'Iit [e Back of sidewalk Burlap sacks to overlap onto curb Back of curb r 2 7, -: Runoff Curb inlet !w \ y l� Runoff Spillway / _ II b 4 ICatch basin Plan View \ le eL 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 'geotextile' 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 1611" 111 Figure 0 -4 2010 IVIO1 Curb and Gutter B r oer DEPARTMENT O F Revised September 2015 ECOLOGY Please see hftp://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 VIashington Volume II e Chapter 4 ® Page 364 BMP C232: Gravel Filter Berm Purpose 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 3/to 3 inches in size, washed well-grade gravel or crushed rock with less than 5 percent fines. . Spacing of berms: • Every 300 feet on slopes less than 5 percent • Every 200 feet on slopes between 5 percent and 10 percent • Every 100 feet on slopes greater than 10 percent . Berm dimensions: • 1 foot high with 3H:1V side slopes • 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 11- Chapter 4-Page 367 MP C232: Gravel Fitter erm Purpose 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 3/4 to 3 inches in size, washed well-grade gravel or crushed rock with less than 5 percent fines. . 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 . 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 II-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 Il- Chapter 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 ll- Chapter 4 -Page 368 ru 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 � i %% % % � % ii�viiiir�iii► U. II anii�� i..I• M■■■ ■■I �� ■■ • ■■ mom al m mu mu �� '■■■ ■■ii� iii�iio .= ii tt,iiiiiiiiiiiiiiiiiiiii�iiiii�iiii!♦A *A. Plum ■■I _�X\� .,/I I�\\��\\��\\ \�A \\A\i\ i\\LL�/\\'\\�/\\ ,\ �� l ' rr rP . I I 6' �I I Minimum max I f I 4"x4" trench I I I u Post spacing may be increased --71 2"x2" wood posts, steel to 8' if wire backing is used fence posts, or equivalent 2"x2" by 14 Ga. wire or equivalent, if standard strength fabric used ii .�/\\\ mu j/ ;Filter fabric ; Al \ \ N' 2 min in IN /�\j/\\\ •I Backfill trench with/4 �/ /\ .��; native soil or " - N. / a". ='pia! 1.5" washed gravel \\/�/\ /in ; \\ Minimum ////\\ 4"x4" trench 2"x2"wood posts, steel fence posts, or equivalent NOT TO SCALE MAME - - i Figure HO=4020 2 "Igli SIR Fence DEPARTMENT OF Revised October 2014 E C 0 OGY 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 e Chapter 4 e 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 min. and a 2'/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 ll- 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. . ASTM A 120 steel pipe with a minimum diameter of 1-inch. . U, T, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. . 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:1V. . 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 ll- Chapter 4 -Page 373 G rig u i e _` -z1,62/[13 S lc Gy c R C hia cc Q I i ©r by ni©n w g [ivl7 ce o d Ponding height max. 24" -11 POST SPACING: 7' max. on open runs Attach fabric to , 4' max. on pooling areas Top of Fabric upstream side of post ` I ' ' �, ii II IA Belt FLOW -- I iiAFii 0 POST DEPTH: top 8" much below ground ,_ Drive over each side of dip As 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 =III=III=III=III III=III=III=III—III=i -,■■■■■■■ 111=1 I I-1111 I I—I I-1111111-1 11-111—I I I1= ......... a l lEI I I-111—III_ I I I—I I I11111EI I I1-111=1 •••► =1 I I—Ill=1 I I—I =1 I I—III=1 I I=1 I I=1 I: ■■■•■. .111=1IIEI111-1111- o III—I11—I11-III—II1— ........ , 1-1 I I—III=111=. a I—I 11-111 =1 I- I I-1 l I :TII—III—I11=1I ii I111=111=1I I-111=111= Attachment Details: =111=111=111 o 1=111=III=III=111=II I I I I=111=1 I I=:;`4 Q-III=III=111=11 E1 11= o Gather fabric at posts, if needed. =III=111=111:1k F 1=11I=111=11 fi 1I1-11' o Utilize three ties per post, all within top 8" 11=111=111— — II1=1I1=1I1=1111111E = —111=111III=1 I I a 1=111—I 11—I11-111-11 of fabric. 11=111E111E111E 111E111E111E111E11E o Position each tie diagonally, puncturing El I 1=111=111=III 1=111-111n 11=III=1 '1E111E111- 11= 111E111E111E111=1' holes vertically a minimum of 1" apart. ;i I I-III=111-111 1-111-11 f=111-1 I o 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. g'N\Roll of silt fence Operation — Post _%' installed Fabric after above compaction �� 0 0ground Silt Fence In L I111=111-T�fi7-1 1= 1=1 1 o fellt I1 1 ► ►=1 - 111= — 1 1 11E 1 11E 1 1 1 E;1 1E 1 1 11— 11E 1 = 11 200 - '11-1 1-111 11-1 1— v III—III III_III=11II III 1 0 1 I=1II=11 =1II= = II-� WIMIUMMY I I10mm III=1 1=111:ill-1II=1I =1I = II— II —� , _ 1 „ ' - I1 1 -11I; _-I ,hell 1;,1 111, 111,;,III , ; l ;ll ;, ,,, ,,.I Il - —fl ! l- Horizontal chisel point Slicing blade I (76 mm width) (18 mm width) Completed Installation Vibratory plow is not acceptable because of horizontal compaction NOT TO SCALE .61110111 Figure 1 =42. 13 VW"' Silt Fence insta a eon by Slicing Method Revised November 2015 DEPARTMENT OF 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 II 0 Chapter 4 e Page 374 Maintenance 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. BMP C234: Vegetated 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 . 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 ll- Chapter 4 -Page 375 Design and Installation 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 of runoff. . The slope within the strip shall not exceed 4H:1V. . The uphill boundary of the vegetated strip shall be delineated with clearing limits. Maintenance 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. $MP C235 Wattles Purpose Wattles are temporary erosion and sediment control barriers 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/Standards/Plans.htm#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 ll- 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 ll- Chapter 4 - Page 377 _ 3' -4' t 4 (1.2m) \\)1/ ,,„ y4 , „,,, \ Straw rolls must be ��,:. /,`�, t , /// , 1. /// placed along slope ��`. ;� %``? v Adjacent rolls contours ;�'ti` . shall tightly abut \_ , 41/ , ,, •:‘, w, _„,_\.*7,-,--- , / , . , _ . <\ ,,,) ‘ i \\\\>s: 1 k AN f ��/,i ,tg,t * fr \ *, a 10' - 25' (3-8m) 4 Yil i ...\,yam J7, \/,r , ,::,/,..„ , /, Spacing depends ::,, on soil type and �/ _42 slope steepness ' *`•. Sediment, organic matter, '1' Sediment, and native seeds are captured behind the rolls. I' i -, x3" - 5" (75-125mm) ` 8" - 10" Dia. �\, L \/ „� (200-250mm) 'AALive Stake Ir *�,.. , �� N. // 1" x 1" Stake �%� � �, \� �/ (25 x 25mm) i i� 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 , 6031131111F ure H-4 2a i4 Viiiii Wattles DEPARTMENT OF Revised November 2015 E C 0 _0 C Y Please see http.//wwwecy.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 e 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. Approved 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 Filtration 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 . 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 (RNtP T5.1O ) 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 III- 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 Stormwater Management 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 Plan View 4"rigid or 6"flexible roof perforated pipe drain sump w/solid lid infiltration trench roof drain overflow Profile View 4"rigid or 6"flexible splash block A perforated pipe CB sump -- w/solid lid 6" 12" f washed rock 1 Y2"-3/4" ' 1'min T 1'min r ` /� fine mesh screen r— /`1 varies 10'min. ► - 5'min. Section A-A filter fabric compacted backfill 6" .ov ft r„ irk,e . Agf '� rAkiltri 24 :�' _ • 4"rigid or 6"flexible rfiflairLfri~i=y perforated pipe 12" =+ ►,► u_+��`—�ifielgia washed rock 1 Y2"-3/4" 24" --►I NOT TO SCALE 1.6.1 Figure III-3.1 .2 Typical Downspout Infiltration Trench DEPARTMENT OF Revised November 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 Ill- Chapter 3-Page 455 1I1-3.1.3 Perforated Stub Out Connections (BMP T5.10C) A perforated stub out connection is a length of perforated pipe within a gravel filled trench that is placed between roof downspouts and a stub out to the local drainage sys- tem. Figure III-3.1.8 Perforated Stub-Out Connection (p.466) illustrates a perforated stub out connection. These systems are intended to provide some infiltration during drier months. During the wet winter months, they may provide little or no flow control. Applications & Limitations Perforated stub-outs are not appropriate when seasonal water table is less than one foot below trench bottom. In projects subject to 1-2.5.5 Minimum Requirement#5: On-site Stormwater Management (p.55), perforated stub-out connections may be used only when all other higher priority on-site stormwater management BMPs are not feasible, per the criteria for each of those BMPs. Select the location of the connection to allow a maximum amount of runoff to infiltrate into the ground (ideally a dry, relatively well drained, location). To facilitate maintenance, do not locate the perforated pipe portion of the system under impervious or heavily com- pacted (e.g., driveways and parking areas) surfaces. Use the same setbacks as for infilt- ration trenches in III-3.1.1 Downspout Full Infiltration Systems (BMP T5.10A) (p.452). Have a licensed geologist, hydrogeologist, or engineering geologist evaluate potential runoff discharges towards landslide hazard areas. Do not place the perforated portion of the pipe on or above slopes greater than 20% or above erosion hazard areas without evaluation by a professional engineer with geotechnical expertise or qualified geologist and jurisdiction approval. For sites with septic systems, the perforated portion of the pipe must be downgradient of the drainfield primary and reserve areas. This requirement can be waived if site topo- graphy will clearly prohibit flows from intersecting the drainfield or where site conditions (soil permeability, distance between systems, etc.) indicate that this is unnecessary. Design Criteria Perforated stub out connections consist of at least 10 feet of perforated pipe per 5,000 square feet of roof area laid in a level, 2 foot wide trench backfilled with washed drain rock. Extend the drain rock to a depth of at least 8 inches below the bottom of the pipe and cover the pipe. Lay the pipe level and cover the rock trench with filter fabric and 6 inches of fill (see Figure III-3.1.8 Perforated Stub-Out Connection (p.466)). Runoff Mode! Representation Any flow reduction is variable and unpredictable. No computer modeling techniques are allowed that would predict any reduction in flow rates and volumes from the connected 2014 Stormwater Management Manual for Western Washington Volume Ill- Chapter 3 -Page 465 area. Fgcj 'g -3 . PPsn w ted Sr o ,c k.. IA random fill 6„ :;;L a.�:; , P�;, `: h.. ._;: '' filter fabric _�� 'ate n:'1:::':- :z;v`=:1 ; : . _ til 4perf pipe 18" min. `e s•�i� ��M��.•.�: p p �1 •Ww-i +•� r��!y ind1 '/2 - 3/q" washed rock gartillig 4111100. , 1111%... 411111:4M... _ pitits.0 ... rm. • will -,__I 24" min. Trench )( Section slope to road drainage system i_ 2' x 10' level trench w/perf pipe Plan View of Roof NOT TO SCALE lDIII '' Figure l l l 3. 1 . 3 vilaill Perforated Stub-Out Connection DEPARTMENT OF Revised December 2015 ECOLOGY Please see http://www.ecy.wa.gov/copyrrght.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 2014 Stormwater Management Manual for Western Washington Volume Ill a Chapter 3 0 Page 466 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 BMPT5.13: 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 VWVHM3 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 V-513 Sheet Flow Dispersion for Driveways Locate drain 25' from _i,' ROifdriveway v slopes toward street. 700 sq. ft. max. between berms l i_ I 4 il I I I } Driveway 1 2 4" Slope ` II I—.— 6' min 1 `,,tw - s4 :.:. . : �. t . - Berm Detail t�UI * :M 5. Diagonal Jh9 25'vegetated berm with '11 25, a flowpath dispersion / trench / Plan Driveway Dispersion Trench Driveway Slope Varies and Slopes Toward Street N,\�// I › / / 1S w:. .' / o I.'. ..-, NA / a, �� u/ , )� / / MaX• 2% Driveway / cross slope Slope isw i / Plan a \w '0a..� ___ Sheet Flow Dispersion from a Driveway 6G��Or 6`'or Flat to Moderately Sloping Driveways I NOT TO SCALE . 1111 Figure V-5. 3.2 Viigia Sheet Flow Dispersion for Driveways DEPARTMENT OF Revised January 2016 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 V - Chapter 5 - Page 910 DMP T5.13: Post-Construction Soil Quality and Depth Purpose and Definition Naturally occurring (undisturbed) soil and vegetation provide important stormwater func- tions including: water infiltration; nutrient, sediment, and pollutant adsorption; sediment and pollutant biofiltration; water interfow 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 themselves become pollution generating pervious surfaces due to increased use of pesticides, fertilizers and other landscaping and household/industrial chemicals, the concentration of pet wastes, and pollutants that accompany roadside litter. Establishing soil quality and depth regains greater stormwater functions in the 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. Applications and Limitations Establishing a minimum soil quality and depth is not the same as preservation of nat- urally occurring soil and vegetation. However, establishing a minimum soil quality and depth will provide improved on-site management of stormwater flow and water quality. Soil organic matter can be attained through numerous materials such as compost, 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% dry weight in planting beds, and 5% organic matter content in turf areas, and a pH from 6.0 2014 Stormwater 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/lnspectionNerification 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) . BMP T5.30: Full Dispersion (p.939) (for public road projects) 2014 Stormwater Management Manual for Western Washington Volume V- Chapter 5-Page 913 if lions \I-1,S., cur Planting bed Cross-Section 4.3 !t . Mulch _ i5F 4: • Loose soil with - visible dark • organic matter • Loose or fractured subsoil Reprinted from Guidelines and Resources For Implementing Soil Quality and Depth BMP T5.13 in WDOE Stormwater Management Manual for Western NOT TO SCALE Washington, 2010, Washington Organic Recycling Council Mill -. 11111 HgureV-5303 Planting Bed Cross-Section DEPARTMENT O®®F Revised January 2016 E C ® L o G V 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 Wester Washington Volume V e Chapter 5 u Page 914 SNIP T5.14A►: Baia Gardens Purpose and Definition 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 and 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 an 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. Design Guidelines Refer to the Rain Garden Handbook for Western Washington (2013) for rain garden spe- cifications and construction guidance. 2014 Stormwater Management Manual for Western 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 n 'JAN 2 5 2018 t-°r 4 4-s A PLANNING,COMMUNITY,&)EC Wit IC DEVEiL•P E !' itEP•L.TmENT (p�T� ® Mailing Address:PO !;ox 547,Anaoortes,WA 98221 Phonon 360.299,1984,gesso 36O 293 193& Stormwater requirements are based on the 2012 Stormwater Management ManuaI for Western WashMrkton Q'SWIA:AIM).A link is provided on the Ci` of Anacotes ewebsOte,kinder Planning (Department,Stormwater Regulations,as well as under the Engineering Division of Public Works. Residential construction 6s exempt from additional storrrrowater provlslc'ns if at involves n.s,expansion of hard surfaces,no use beyond that previously existing,and results In no significant adverse hydrological impact. Building permit applications for lots that are part of a subdivision that was rec Med no more than 10 years prior to the date If the complete building permit application may continue to use the storiroewater codes in effect at the time the subdivision application was submitted, if stonnwater was addressed at the subdivision/plat level. if cornstru.tion has not started as off ianuarry it,2022,the site will be subject to the 2012/2014 manual. Of your project adds less than 2,000 sq,ft.of new plus replaced hard surface area,ARID which disturbs less than 7,000 square feet of land,you must consider all 13 C?lerntents of the Construction Stormwater Pollution Plan QS' 'PPP), Fill out the S 'PPP Checklist and explain how the elements are considered,or describe how site co nditions render the element unnecessary and the exemption from that element is clearly just+{oed.You will not need to continue with this document. Of your project adds 2,090 sq.ft.or more of new plus replaced hard surface area,DOS which disturbs 7,000 sq,ft.or more of land e Minimum Requirements gob of the SU'Ml dr 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 103,900 sq,ft.or m ore of native vegetation to pasture—Minimum Requirements it 9 of the SWiViNiNMY apply.If Minimum requirements i 9 apply, please see the Large SE?le Stormwater Plan Checklist for additional submittal requirements. ©mow 4ameo 4 _ Site Address:. 4/© 414riri40e. di/eel./ C dadff Description of the Project. 4L.c :J , [p ' i !_f Pm Developed Conditions Run.t.of the Situ° Page A of 4 March 22,2017 Li,eveloped ConditionsRunoff of the Site: Summarize difficult site parameter_,the n1 wag bMange syslao ,and drainage to area fr, rn adjacent properties,including bypass tows: 0 Hydrological Site Plano Collect and analyze information on existing c•nd¢gaons to aid in determining low h pact development feasibility m which locations are most appropriate to evaporate,transpire,and infiltrate,with the following bnfformatxlrn: o Sarin by Land Sagwe rr,Engineer,or "they qualified professional:Show existing public and private development,utility infrastructure,hydrological features(seeps, springs,dosed depression areas,drainage awakes,stream^s,wetlands,and water body swraey and classification report showing wetland and buffer boundaries),flood hazard areas,geological hazards,buffers,aquifer and wellhead protection arias,topographic features that may act as natural stormwater st,trage,infiltration,or conveyance. include the natural receiving waters that sttormwator runoff will either directly or eventually discharge. Show topography,display acreage and outlines of all drainage basins;existing stormwoter drainage to and from the site; rotates to existing,construction,and future flows at all discharge paints;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 dory parrs as Mows: o Up to 10%slopes o 2 ft.contours a Over AO to less than 20%slopes o 5 ft.contours • 20%or greater slopes o 10 contours g ElevatiLns at 25 fta intervals o %cgs Report:Done by a soil scientist ceedflod by Soil Science Society of America, licensed sewage designer,or other suitably trained persons working under the supervision of a prroffessaonal engineer,geologist, hydrologist,or any other professional supervised by an engineering geologist registered in Washington State.Q5oils Report Page 2off4l March 22, 2017 must include details as listed on Pg.79). in addition,describe soils f v none,erodibilit , settleability,permeability,depth,texture,and soil structure. Testingshould occur between December 1 and April 1. o Soils Map:Based on the report. o Prelirrilnary 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 of 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 II proposed contours,show all cut and fill slopes indicating top and bottom of slope catch lines,and identify developed condition drainage basins. '1 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 Stonmwater Pollution Prevention Plan($WPPP)—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. 0 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. Priorto Final,Stormwater Inspection ❑ 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 fi Page 3 of 4 March 22,2017 0cm; and any public flthill that dSSp9ap the Docation of ©na t e BaliPs and the arias sa Sd by th© m0 These documents be recorded and ttachSd To a dSSOarafon of covenant and grant of easement associated with each Oct that QnddadS5 Onos to O Mp5e Provide design dS&aSOso figures, and mahtenarce instructions for each BMP. Provide a written summon? of how at comp es with The appf ace ace requirements ° dpr Mood Qmrf-Dourz D optrratBow n air once ikkiMgg include a mamaaa for each flow control and treatment facflfot y including any distributed big retention fad9D SSs that are used to SSDp meet flow contro 0 and/or treatment rreq rem t ° The macana than induda a description og the facility, what at, dour and how it work at must aria identify and :describe the frinabrntenne Teaks, and the frequency Of each Tast The teas zs aid frrquatSSSs mast meet the standards oil The SWMMWWO Odade a maintenance activity Bog that will $ Satan what actions WM have been taken and wh. erre of shoWd be kept and made ava &QahQQ fair inspection by the C0ty0 ❑ of C o tea© ® Svc uwagBt 17®P PFSRS it 1@bitahed FOM t ©S©fl 4 Weatron Path( OQs @ CS ©am S ® St@nlimaer MansgeumigoR s GYM SSa My flow control & Treatment f SSD5tS and indite St© mwMc v management B Ps for which the app nt identifies operation & maintenance To be the resp©nsNinty of a private car masts have a dScaarrallas of covenant and grants oiV easement° After aty apr©vaL the dedarataor of covenant and grant ©f easement must be signed and recorded . Design det aik, figures„ and maintenance instructions for any MP shaDO be attached ° A map showing the iccation ©f newly ØdantS and ?elated trees chimed as row redaction crSdfs shaSQ SSo be a ached ° D nw@ridi Dongme Sg Record total Impervious surface area of the site and their 4ocataons with the cony auditor. Dv signing Sllowv pa a s term ini AM pa hove r©aS ant7 undontand the storm/Mr rrp8rage ao Be save not cyoa haw cheted ©.ff iOB aavtabb bans. - (17 ait Appkant Sbo rature Date Page Gof4 March 22, 2017 EXHIBIT "A" 1410 LATITUDE CIRCLE LOT 4, PLAT OF 48 NORTH P133662 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 located at 1410 Latitude Circle, which is Lot 4, Plat of 48 North, and is 10,690 square feet in size, Zoned as R2. Pre Developed Conditions & Runoff on the Site: The property is vacant. The site slopes from the east to the west at a grade of approximately 12.0%. The property is bounded as follows: NORTH: 4315 Eagle View Court, P31583, and 4307 Eagle View Court, P31682. EAST: Port of Anacortes, P31664. SOUTH: Fully improved street of Latitude Circle and Lot 5 48 North. WEST: Lot 3, 48 North. Developed Conditions & Runoff of The Site: The proposed improvements are as follows: Construct a SFR with an approximate lot coverage of 21.3%, and an impervious lot coverage of 38.2%. No detention was required for the Plat of 48 North, but there is an existing water quality bio-swale for the plat. All roof drains and footing drains will be hard lined to the existing stormwater collection system. The point of connection for Lot 4 is located in the northwest corner of the property. 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 adiacent properties, including bypass flows: The site slopes from the southeast to the northwest at an approximate grade of 15% and the disturbed soil has been seeded and/or mulched to reduce erosion. The only tributary drainage the lot may receive is from Lot 5 and the Port of Anacortes. Lot 5 will have its own drainage self contained so as not to impact Lot 4 and intercept drains will be installed to adequately eliminate impacts from the east. 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: A "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. i / y l —) HOUSE N - all Ila — EXIST LANDED GENTRY DOMES AND COMMUNITIES PROPOSED PERIMETER SILT HOUSE FENCING(TYP)PER BMP C233 JAN2 •5• 2n 1 GENERAL NO TES CHECK DAM PER BMP [J. u (� C207:CHECK DAMS, OWNER: PLACE SILT FENCING ON AS NEEDED. I II'' EXIST DOWN STREAM SIDE OF LI LANDED GENTRY GRADE STOCK PILE,PER BMP C233 - 504 E. FAlRHAVEN F BURLINGTON, WA f Inv tse.o rii°fl 98233 mar +aoo sar EXIST GRADE ! i`- '``~,,n,1 14360)-755-9021 i • INLET P •TECTION PER 6220, rx x x x x x ' x x x x X x BLOCK • GRAVEL FILTER TYPE % EXIST.$D LOT LINE MUt CNING pN X x x x --.x x x "l x x' x BUILDING: !� / CONNECTION BMP C121 AND R NH MAIN FLOOR AREA- 2,109 SF 7 ' pOST�ONSTRUC� / • i• � ;� _N T5,13: If{ b PROPOSED 4°SCH �� LOWER LEVEL AREA- TOTAL LIVING AREA- 2,1114 , _ • , i i ...`€�.— S01t OUAt' K 40 PVC DRAIN LINE- "_ coo GARAGE/SHOP- 1,003 SF / I I _ Saar raoo '_ 0 SITE: 10' FRONT YARD ~ 'a"°s� �' ,q i - TYPICAL EXISTING SETBACK Bc,fJ71LfTY , ; • �_� — ZONING: j STORMDRAIN EASEMENT LINE Sc ; / • MINE(TYPICA ) 2D' FRONT YARD ca v I' 1 'x GARAGE SETBACIc� �'i Q R2 - RESIDENTIAL LOW DINSITY • I • I SOIL STOCKPILE PROPOSED 4'DIA. W SETBACKS: x 1 LOCATON SANJTARY Tn2 ER p BMP C121:M'CaNS1NiRUCTIpN ALL SETBACKS !N COMPLIANCE LOT LINE/ ( (COVER WITH PLASTIC 2 i T513;pOST AND DEp� LOT LINE WITH CITY GUlDLlNES I 1D11Souct A:— ' G• , , t PER BMPUC1010N FENCE I / 7 1 I x • I Q HEIGHT. 13 1 f PORCH MAX. ALLOWED: 35' I I 1 0 PROPOSED:UNDER I / PROPOSED 4"SCH I i8d82 n'�. '` ; IL____:]' •• k 1 40 P C DRAIN LINE H. 0 PARKING: y 1 era 4V RfAR YARD OI 6.7% IDING SETBACK 2 IN GARAGE, 2 IN DRIVEWAY /1 / / LOT3 LOT 2' // PROPOSED4'DIA. I' / xII/ �� I R Q Ni LDT COVERAGE % Ir I Fl DRNEWAY JO / WGCP CFF i PLACE CONSTRUCTION FENCING / SANITARY SEWER I INLET PROTECTION PE• 22Q / (CAJON AROUND / x BLOCK&GRAVEL FIL I• TYPE L r�z • LINE PLUS BiSTING TREE AT DRIP B 2%2�GS REA: / F. /j i /� I t89.0 §:1°/u j' LOT AREA: inn-7; PERCENT COVERAGE: 1 I 4"CONCRETE/CURB OR I � 2,275 / 10,690 = 21.3% /' I THICKENEDEDGE I/ , ril�� , ItlI MAXIMUM ALLOWED: 37.5% PROPOSEDPERIMETERSILT x 1 0 0 0 0 0' FENCING,(TYP)PER BMP C233 190.8 ' CHECK DAM PER BMP / IMPERVIOUS COVERAGE GRADE LOT LINE - PROPOSED 4"SCH _ C207:CHECK DAMS, L 202.0 _ 40 PVC DRAIN LINE AS NEEDED. ° EXIST BUILDING 1,935 SF. I I .— _ r-- cacao ; �Qr GRADE STEPS/WALKWAY 60 S.F. •\'% ( -nue FRONT PORCH. 84 SF. 1 I --- __ x ' LOT LINE COVERED DECK: 275 S F. I N DRIVEWAY 1.729 S.F. ll l ; TOTAL: 4,083 SF. - t I I • • PROPOSED PERIMETER • ' - i' / 190.5 I I CONSTRUCTION FENCE LOT AREA: K EXIST ;' PER BMP C103 10,690 S.F. GRADE �, - �_ _ 1.0% i ;/ •• �� PERCENT COVERAGE: • ` --`. I 4,083 / 10,690 = 38.2% l EXIST.SANITARY ( I I o il MAXIMUM ALLOWED: 48.0% \ SEWER LINE / I I •// I • \\�� • LOT 5 ABBREVIATEDLEGAL DESCRIPTION: I / LOT 4, 48 NORTH PLAT & PUD, SECTION �� 22, TOWNSHIP 35 NORTH, RANGE 1 .00 185.8 '' Fs EAST, W.M., CITY OF ANACORTES, = G I DE \� SKAGIT COUNTY, STATE OF WASHINGTON, tic111011116\ �� '! TEMPORARY CONSTRUCTION CONCRETE �sT ENTRANCE P c BMP C105 A.F. 201705020028. SSW / ': IONsi� \ (SIZE TO FIT)' I Z SDCB LOT LINE 8 RIGHT-OF-WAY `, WM \ • _ LINE ♦ / I j� �� ` Ar EXISTGRAPHIC SCALE TIT D s �\ GRADE _ L _ _ 10 0 5 10 20 C lc.4>L 4 / -. _ J Erosion Control Notes for Residential Construction-City of IRC�—E SDC o F�9i_ \ A \ L Anacortes =-=�—� r -7' . \H. . ( ( e: FEET �- 7. \ A. Erosion Control Best Management Practices shall be in place per HoTtix. 5c¢le: 1 hrch = f0 Feet . ::) 187.E ` \ the accepted site plan prior to any construction start. /7:1`'f B. The erasion control shall be inspected once a day and modHied _ ,/ ......... .:._ , ' 188.3 \ / K to meet the surrounding conditions as needed, 48 NORTH S— \ `®/ EXIST \ / 7� C. The storm drain system shall be cleaned daily(Section 7-07.3). \ f I All drainages stems shall be cleaned to the acre lance of the GRADE' \ Y P LOWMAN a' ® / --� City of Anacortes prior to acceptance ofthe project. 2—CAR GARAGE RIGHT / \ D. Stabilized construction entrances and roads shall be Installed at \\\ - _- _ \ / II the beginning of construction and maintained during the duration i- -` _ \ \ i of the project.Additional measures may be required such as I '` \ A I wash pads to ensure that all paved areas are kept dean.No mud INLET PROTECTION laauowedto enter onto City streets. EROSION CONTROL & SITE PLAN i P.ER�1220, CATCHBASIN_ - \ /' 1 j E. Any soils exposed that will not be disturbed for hvo(2)days /7"/. ,- FILjER TYRE \ \ I during the wet season or seven(7)days in the dry season shall LOT 4 (P 133662) / \ ` be immediately stabilizaetshdffibecitehgvethieap:ofvedESCmethods/ \ \ seedin mulchin ri ) 1410 LATITUDE CIRCLE // \\ \' I ( 9, 9, Png, c.F. Two(2)weekspriortnning the wet season(October / \ ; \ \ LOT'6 1), alldisturbedareasshallbereviewedtoidentifywhlchones ANACORTES, WA / \ \ can be seeded In preparation for the winter rains.Disturbed / \ - I 1 l areas shall be seeded within one(1)week of the beginning of the / \ + I wet season.A sketch map of those areas to be seeded and those / // \ \ \ areas to remain uncovered shall be submitted to the Project JOB NO: PLAT OF "48 NORTH" / \ 1 I / ( Manager.The Project Manager can require seeding In additional / 1 \ l J7 areas in order to protect surface waters,adjacent properties or DESIGNED: LG -A / \ I / I drainage fadlities. DRAWN: \ ` , \ i {� I �V G. Penalties for an Erosion Control violation are subject to a$300 to LOT 32 , ! ( I $1000 fine under Chapter 17.88-Penalties for Violation.Each DATE: 01/19/2018 \ ; /- k SSMH I j I / day is considered a different violation. SHEET I F1 1 1 '' i 1 /' \� 1 0 2 . -------- MD WI OD 11=MINI MIMI= IIII 01=0 GEN=111 iMMEI. 4IMINIMMIMM til=11MINIMID LANDED GENTRY HOMES AND COMMUNITIES ,.• I: : ___ . ' • 0 13111 St tv5•-t , Ill- Lovric's Sea-Craft 0 P 141h st 150-t St n 3 o. > ttati st 573) ro Shannon Point •-c- AO 17t11 St - .44 tt" •,=:k -P 0 . ' 0. . ' '1 SV,-"i C.' I Sift St Shannon Point , 0 A Marine Center 13 stl Vas% 41'3'6 77m5- 0 1.- › _ r 01 at 3 o, co co_ (Th) 2 :, '). $.0 .,-.6 \'' ml 'i° S‘ '' • •A', 0 Au it. , A _ 44 1%. • _,. ' ar I -..,•:= L---: •,J.:,-:, ' ,,,,,S (4, : 4... 75 SITE LOCATION ." e.., g (Do 4.06 ry%Ai* 5 ' , e.. s•,\'7 o..v , — 4 ..P. = E Ship Harbor Inn* es-.. ,,,,c Cranberry 0 (De -,1'• .. rq : Lake Park . to koe r, •S hc- 1: San Juan Airlines 0 • Sun5e1 Ave Sunset Ave - SIP° ,..0.... 24thst P• .d. tt ..iV • 500,1°af St' ' "cb a 1111 IE- -!:. Anacortes 30lItSt : -13 n•.e.. 'tS. 0i. c%%PI ay ,o• i , -.. i Airport S5-.. sirs •lI›<It:. 1 0 V o ? Z • 0, e d - Stetting --,- _g•• (Ps' r.,••.', DOon t.,....._ .1 330 -§ Old Salt's Dell&Merkel el In o Little --,:, -, •,:. ANACORTES WA .9 ., ..„-. , _.,.., % - . 4§ • Skyline Marine Center •-.;, 6, 4 --. • Lak 51.: ....:, (t., -7 •o '1 1:, - 3 - ._ 4.1 .0440e a cfilmi.ii,; - co ,v• ti ;i7t1,:-t c• a tii R 48 NORTH 0 - n 441 Skyline Marina 0 o, r O (•IJr 44 N'' r 7.1 Y, •1,,,,,., -e-N LOWMAN • Owners Association 9.14. 0_ a.3 M 1, •:...7. 2-CAR GARAGE RIGHT .e...cs :s."; - ... zGcif gle Queeivio9 a) EROSION CONTROL & SITE PLAN 1 LOT 4 (P133662) Map data @2017 Google 1000 ft L . _ __-g 1410 LATITUDE CIRCLE VICINITY MAP ANACORTES, WA LOT 4 (P133662) 1410 LATITUDE CIRCLE • JOB NO: PLAT OF"48 NORTH" ANACORTES, WA DESIGNED: LG DRAWN: DATE: 09/11/2017 SHEET 2 of 2 tx1.3 1. HOUSE �MIMI = w EXIST LANDED GENTRY HOUSEDOMES AND COMMUNITIES 183.7 EXIST GRADE- I- 198.0 filar ear EXIST rxar / --_..,_ _. _...._ __ EXIST.SD LOT LINE-- �' `=- = CONNECTION • I ' 11 = . ._ _ —_. .-_ c. it 0 •-PROPOSED4'SCH -I `' 40 PVC DRAIN LIME \� SD — — Ir MOO.-- 10'FRONT YARD .+—. EXISTING SETBACK & UTILITY ' r . . . . . STORMDRAIN EASEMENT UNE I ' -- — _ LINE(TYPICAL) ar FRONT VAR, GARA :AC LOT LINE 1011 Jcx� tJ LOT 4 :;11 i,!a7/' 1 isoir I LANDING 1 191.50 UT I PEONPROPOSED 4"SCH 1 L _ , 9 ��i REAR YARD E 40 PVC DRAIN LINE ' � � 1 . . LOT 3 f LOT _ r OT 2 PROPOSED 4•SCH I' GARAGEis, ra OH PLACE CONSTRUCTION I• DRIVEWAY 4 f9t.00 OFF 40 PVC DRAIN LINE ,1 I f9fso OFF FENCING AROUND EXISTING 1 II TREE AT DRIP LINE PLUS 6'. 188.0 ,D., -- - - L _ __ , , ,,,-,, „,. co, ,N,. ,e. 190.6 EXIST LOT LINE PROPOSED 4'SCH UL 202,0 GRADE 40 PVC DRAIN LINE f�\ GRADE sect _ _ f-- — — — -- -- —�a°v' — — — — _ — .fv.ss' -- — rate• "I JLOT LINE EXIST !• \ GRADE II —— 1 EXIST.SANITARY a SEWER LINE ; /ice N �� / I i I LOT 5 .'� 0_ I I I I90.00 185.6 I I EXIST GRADE \ CONCRETE /ir n• /-- ell*ilitot •/. _ EXIST,SS: Q CURB&GUTTER r ; i SSMH \ CONNECTION I I Z WM 7/, \SDCB - - LOT LINE& � 4,.,) \ ; I I �' RIGHT-OF-WAY `® WM \\ �' N \ ' 192.3 I I TITU®E �' Q� \\ `�IisT \ GRADE GRAPHIC SCALE 1—1 T :. • L _ (._._ __ 10 5 10 20 CIRC SDCB. Eby, \ �� \\ ( IN FEET ) \.: Hordx. Scale: 1 Inch 10 Feet .4. \ q <- (c-,../, � �' \ ` s" EXIST \\ - \ 48 NORTH i% �, GRADE \ l'/C—i _� s \ - COWMAN �� LANDSCAPE NOTES: \ ; 2-CAR GARAGE RIGHT �� 1, \ ; \ PROVIDE lll TREE (EXISTING OR ADDED) PER 1,000 1SQ. FT. OF LOT (11 TREES LANDSCAPE PLAN AIII /NNW ,/ \ \\\ `-'' \` 1 MN. o VERIFY LOCATION W/ BUILDERS W/ A MINIMUM CALIPER (PER CODE.arAmr LOT 4 (P133662) �'' \ \\ `t \ LOT 6 TREES PROVIDED WILL SE A COMBINATION OF DOGWOOD, ALASKAN CEPAR, 1410 LATITUDE CIRCLE ,� \ \\ • �1 \ VINE MAPLE 4 WESTERN HEMLOCK (VERIFY LOCATIONS W/ BUILDERS. VERIFY ANACORTES, WA ' \ `\ \ TREES TO SE REMOVED IN FIELD W/ SLDR. IF APPLICABLE. /i� \\ • j 1 JOB NO: PLAT OF"48 NORTH" �/ \ PROVIDE LANDSCAPING IN A COMBINATION OF SOD LAWN AND PERENNIAL DESIGNED; LG LOT 32 1 PLANTING BEDS TO COVER A MINIMUM OF 20% OF THE LOT (2,130 SQ. FT.). DRAWN: I �1 . 'SSMH I I VERIFY LAYOUT W/ BUILDER. SHEETHEE: 01/19/2018 ,. , 1 of 1 I I 'I `\ 1 1 see INNIMMe OMB SWIM HOUSE 1111111111111110 EXIST LANDED GENTRY HOMES AND COMMUNITIES PROPOSED PERIMETER SILT HO USE FENCING(TYP)PER BMP C233 GENERAL CHECK DAM PER BMP C207: CHECK DAMS, OWNER: PLACE SILT FENCING ON AS NEEDED. 183.7 DOWN STREAM SIDE OF LANDED GENTRY EXIST STOCK PILE, PER BMP C233 •• , 504 E. FAIRHAVEN GRADEN }" BURLINGTON, WA 73133' 198.0 W ` ' 98233 sass' EXIST " 1-(360)-755-9021 INLET P,•TECTION PER 6220, <X X X X L �.n GRADE LU © a N X X, ' &X X X X X X X X x-' X Y--�X < EXIST. SD LOT LINE BMp C121'.M t NINRUCt N _ yBUILDING: BLOCK : GRAVEL FILTER TYPE x X X X - W =` < � rCONNECTION pOS PEP O Z Q A O0 a TOTAL LIVING AREA- * 36 SF NST X _ y 'T5.13'. kISY AND PROPOSED 4" SCH �R O o J 1 22� 9 MAIN FLOOR AREA SF LOWER LEVEL AREA SF -. _ �,r,.� SOtL OUA F 40 PVC DRAIN LENS GARAGE/SHOP- d3 SF �•: 10' FRONT YARD ( -� . ._.. '` •• „- r,00 oo �.. Z D z 0 GE�SH - 1,0-- - law O SITE: EXISTING O u SETBACK & U17LlTY r 1 _X � —�� LL 03 0 ( W TYPICAL STORMDRAIN EASE LINE 1 , v Cl.cc i o EASEMENT O. Q w w ZONING: /LINE TYPICA ) 12U FRONT YARD, o Q d z x GARAGE SETBAC`ICJ f - oa, _� Q I� o R2 - RESIDENTIAL LOW DINSITY PROPOSED 4"DIA, I a j - ¢ 1i SOIh STOCKPIE E g SANITARY SEWER w UtCNtNG& U Z w o _0 (9 BMp C121'MCONS1R11CTlON Z m SETBACKS: { I LOCATON' H ALL SETBACKS IN COMPLIANCE LOT LINE 1 jSTORM TIC . LOT LINE C( p O W EVENTS COED O OIL OUALt J w > z SIDEY5' COMBINED 1j• , REAR YARD MIN 30 .....,...� <:........ ,...�,.....,. _ I sco .�.� _ .}. 181.50 LFF DECK a. O. cc cc - t LANDING �; o d a m ¢ FRONT YARD MIN 10. 20' GARAGE X - LOT PROPOSED PERIMETER w Ca a D _ • CONSTRUCTION FENCE ° g ¢ r / , Ii ' ` PER BMP C103 X I_I �� = P� HEIGHT. I 8 8 POISCH it m ) MAX. ALLOWED: 35' j [ 1 g i n 1 , PROPOSED:UNDER PROPOSED 4"SCH x 78&82 t �,}, l t� PARKING: 40 PVC DRAIN LINE FS PV BULDINGASETBA�K o 2 IN GARAGE, 2 IN DRIVEWAY I j 6.7% x LOT3 w • LOT 2ii' LOT COVERAGE PROPOSED 4" DIA. PLACE CONSTRUCTION FENCING w DRIVEWAY 191.GD G 797,50 GFF SANITARY SEWER I INLET •PROTECTION PE• 220, GARAGE/SHOP W > AROUND EXISTING TREE AT DRIP BUILDING AREA: �' X I BLOCK&GRAVEL FILL,• TYPE 2° • LINE PLUS 2,275 S.F. t89.G u) - V LOT AREA: FS -6.1% m, 10,690 S.F. / U + _ .. _. .. :. . . ., PERCENT COVERAGE:: I • -° �t �w^ 2,275 10,690 = 21.39 4" CONCRETE CURB OR ° _ os . ` �� THICKENED-EDGE x '�� 8 m 137 Q Lug t�'"� g • • y ��-�� _ MAXIMUM ALLOWED: 37.5% PROPOSED PERIMETER SILT \ 190.6 �` FENCING (TYP) PER BMP C233 EXIST --LOT LINE PROPOSED 4'SCH CHECK DAM PER BMP a jigr5 I b �/ C �L) `�� IMPERVIOUS CO I/ERA GE I o C207:CHECK DAMS, s 202.0 / I GRADE 40 PVC DRAIN LINE AS NEEDED. EXIST ( x �. �� BUILDING: 1,935 SF. t1 >� I Baez' -_ +aw' GRADE dot, u - S.F. - 3as3 STEPS/WALKWAY. 60 S F I I �- g�a o 1122a• 6 FRONT PORCH: 84 S.F. ? M I LOT LINE r / ✓a o c COVERED DECK: 275 S.F. i • -� it TOTAL: AY. 1.729 S.F. " PROPOSED PERIMETER TOTAL: 4,083 S.F. ----' • 190.5 " I o CONSTRUCTION FENCE ° S1 } Ih SkitL ptf- `-`C•kf �d I/`f LOT AREA: EXIST PER BMP C103 �t7 10,690 S.F. )fie.GRADE 1.0°!0 �f o &a" � e PERCENT COVERAGE: , � I �Ictqcm - 4,083 f0,690 - 38.29 �I -— EXIST. SANITARY X I o MAXIMUM ALLOWED: 48.0% �'- SEWER LINE I ° �` / LOT 5 ABBREVIATED LEGAL DESCRIPTION: LOT 4, 48 NORTH PLAT & PUD, SECTION '\.,'`vq9 I 22, TOWNSHIP 35 NORTH, RANGE 1 ,\ ,. 7 185.6 I FS,oG EAST, W.M., CITY OF ANACORTES, JAN ": = \ asvEXIST v =�, GRADE s �1 TEMPORARY CONSTRUCTION SKAGIT COUNTY, STATE OF WASHINGTON, ,_ ExtsT;�ss • : ENTRANCE PER BMP C105 A,F, 201705020028. a CONCRETE lir ''. r,/g � SSMH } ( ' �- t%)NNECTIO,N\ CURB&GUTTER 410*WM� \ �, (SIZE TO FIT) Z i 4,0'v " s LOT LINE& . SDCB RIGHT-OF-WAY. WM Ili 0 I .0 LINE +/ ,-•::\:,/- �, �� . ° ; • EXIST GRAPHIC SCALE ��,�' -� ;_ .0a �fi ° GRADE .: . �\ N f R �Q 0 J� �Q 2d 9o�AiL • Erosion Control Notes or Residential Construction-City of ��s +� � SDCB 4,F4y, ' V Aneco tes L , �p \ ( IN FEET i Z ..., ,0-.:1-'' - ✓' , \, A. Erosion Control Best Management Practices shall be in place per Horiz. Scale: 1 Inch = /0 Feet < 4iN. 187 4 the accepted site plan prior to any construction start. r" FS B. The erosion ;ontrol shall be inspected once a day and modified .0. a, 188.3 \ to meet the surrounding conditions as needed \ EXIST \ C. The storm drain system shall be cleaned daily(Section 7 07.3). 48 NORTH °� "" GRADE \ - - - All drainage systems shall be cleaned to the acceptance of the p COWMAN ��/ .: - ' \ City of Anacortes prior to acceptance of the project. •4° \ ,,,,, :; D. Stabilized construction entrances and roads shall be installed at 2-CARRIGHT v the beginning of construction and maintained during the duration R GARAGE \ AV ° /, — I'Iof theAdditional berequired such as —- \ \ project. ona measures may 7: \ wash pads to ensure that all paved areas are kept clean. No mud dr /' �' INLET PROTECTION s allowed to enter onto City streets. EROSION CONTROL & SITE PLAN �. v PER'0220, CATCHBASIN -1\\* A / \ E. Any soils exposed that will not be disturbed for two(2)days \ during the wet season or seven (7) days in the dry season shall LOT 4 (P133662) i7 FILTERTYflE m J • I be immediately stabilized with the approved ESC methods 1410 LATITUDE CIRCLE / N N ' \ \ (seeding, mulching, plastic cover ng, etc.) // \ 00 LOT F. Two (2)weeds prior to the beginning of the wet season (October ANACORTES WA / 1 1), all disturbed areas shall be reviewed to identify which ones \ TileLl': / \ , can be seeded in preparation for the winter rains. Disturbed / \ areas shall be seeded within one (1)week of the beginning of the / ,, \ ose / V „ JOB NO. PLAT OFNORTH" wet season A sketch map of those areas to be seeded and those areas to remain uncovered shall be submitted to the Project "48 N " / ) I Manager. The Project Manager can require seeding in additional \ DESIGNED: LG // \ )•- ) areas in order to protect surface waters, adjacent properties or / \ ( I drainage facilities. DRAWN: LOT 32 �� 00 ( G. Penalties for Erosion Control violation are subject to a$300 to 8),;-- �, .; : ) $1000 fine under Chapter 17.66- Penalties for Violation. Each DATE: 01/19/2018 y SSMH ) day is considered a different violation. SHEET I 1 of 2 see IMMO 41111111111111111 111.1111111. 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Li �� i o Z a ANACORTES , WA cc =s 48 NORTH zse COWMAN 2—CAR GARAGE RIGHT Raw �,T EROSION CONTROL & SITE PLAN Map data ©2017 aoogle 1000 ft .- __. w �. ,,..„. LOT 4 (P133662) 1410 LATITUDE CIRCLE VICINITY MAP ANACORTES, WA LOT 4 (P133662) 1410 LATITUDE CIRCLE JOB NO: PLAT OF "48 NORTH" ANACORTES, WA DESIGNED: LG DRAWN: DATE: 09/11/2017 SHEET 2 of 2