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HomeMy WebLinkAbout977700024 Stormwater Mgmt ~ '" .. \ RE(~EIVElT) STRATUM GROUP 1451 Grant Street, Bellingham, W A 98225 Phone (360) 714-9409 -; ..,~ p~. ,."'-.' r'.; f'" .",~"l if ..-,i "~I ~;. '..,' :) October 25,2006 IHHRX(l~I:U1INn urn Scott Sprague Accumar 1180 NW Finn Hill Road Poulsbo, W A 98370 Re: Drainage and Erosion Control Cable Lift at 530 Reinier Road Norland, Washington Dear Mr. Sprague: Thank you for sending me the site plans and designs for the cable lift at 530 Reinier Road, I spoke with Dee Tour du Monde and she indicated that the County would require a Drainage and Erosion Control Plan. This requirement is from Jefferson County Code l8.l5.275(2)(a)(i) states that a drainage and erosion control plan is required when a project is proposed within a geologic hazardous area or its buffer. The proposed project will disturb an area of less than 50 square feet. The disturbed area is located with the geologic hazard area buffer. No disturbance will be taking place within the geologic hazard area (the steep shoreline bluff slope). This project is considered a small project and is only required to meet Minimum Requirement #2: Construction Stormwater Pollution Prevention. For small projects the applicant shall consider the twelve Construction Stormwater Pollution Prevention elements and implement applicable BMPs. There is no additional submittal required, I have attached a completed copy of Jefferson County Stormwater Calculation Worksheet and a copy of Jefferson County Construction Stormwater Pollution Prevention Best Management Practices (BMPs) Packet. Based on my review of the project drawings, I do not anticipate that the proposed project will have any negative affect on the stability of the steep shoreline bluff slope. The only area of disturbance will be the very small area needed to constructed the supports for the cable lift at the top of the bluff within the buffer area. APPROVED STORMWATER PLAN DEe - 8 2006 r .. ... I make the following recommendations to prevent and erosion and damage to the geologic hazard on the shoreline bluff: 1. No debris or soil should be placed on the bluff slope during or after construction. 2, Excavation should be limited to only that area necessary for the installation ofthe concrete supports, 3, The topsoil area and salal plants excavated for the installation of the concrete supports should be set aside and utilized for cover on areas disturbed by the excavation work, 4. Other than trimming of the salal, vegetation and topsoil beneath the area to be covered by the deck landing area should be left undisturbed. Stratum Group appreciates the opportunity to be of service to you. Should you have any questions please contact our office at (360) 714-9409. Dan McShane, M.Sc., L.E.G, Licensed Engineering Geologist IR 'IE(~lEX\V'1E W) Sincerely yours, :nJ~ ,JHffASUN~UUNI~ U~U ..,.."-, ~> ~ /""""'>..-..,~...- Y .,...."" ::;; L.'I" , \- w '- '-' L,.;',-'\,j Stratum Group File:4,26.04DIII 2 APPROVED STORMWATER PLAN TV )EV', .OPMENT 621 Sheridan Street. Port owtfS'efiitlJRWashington 98368 360/379-4450 . 360/379-4451 ax http://www.co.jefferson.wa.us/commdevelopmentl JEFFERSON DEPARTMENT OF CO Stormwater Calculation Worksheet I MLA# PROJECT/APPLICANT NAME: R1E~ ~IE~\r1E[) I. ,r.: l. t n ,r~, J; f"~, :'. .~" ,\J' ,,~) .t.~;;i) JHffR~UNLUUNI~ U~O DETERMINING STORMWATER MANAGEMENT REQUIREMENTS: This stormwater calculation worksheet should be completed first to classify the proposal as "small," "medium," or "large." The size determines whether a Stormwater Site Plan is required in conjunction with a stand-alone stormwater management permit application, building permit application, or other land use approval application that involves stormwater review. The basic information will also be helpful for completing a Stormwater Site Plan, if required. Size of parcel acres PARCEL SIZE (I.E.. SITE) Size of parcel in square feet ,~ CZ ~ 00 0 sq/ft , An acre contains 43,560 square feet. Multiply the acreage by this figure, Land-disturbing activity is any activity that results in movement of earth, or a change in the existing soil cover (both vegetative and non-vegetative) and/or the existing soil topography. Land disturbing activities include, but are not limited to clearing, grading, filling, excavation, and compaction associated with stabilization of structures and road construction, Native vegetation is vegetation comprised on plant species, other than noxious weeds, that are indigenous to the coastal region of the Pacific Northwest and which reasonably could have been expected to naturally occur on the site. Examples include species such as Douglas fir, western hemlock, western red cedar, alder; big-leaf maple, and vine maple; shrubs such as willow, elderberry, salmonberry, and salal; herbaceous plants such as sword fern, foam flower, and fireweed, LAND DISTURBING ACTIVITY. CONVERSION OF NATIVE VEGETATION. AND VOLUME OF CUT/FILL Calculate the total area to be cleared, graded, filled, excavated, and/or compacted for proposed development project. Include in this calculation the area to be cleared for: Construction site for structures Lf6 sq/ft Drainfield, septic tank, etc. JlA sq/ft Well, utilities, etc, VII sq/ft Driveway, parking, etc. #A sq/ft Lawn, landscaping, etc. )/;1 sq/ft Other compacted surface, etc. 1/11 sq/ft L' Total Land Disturbance 76 sq/ft [over] stormwater calc worksheet doc - REV. 10/1212003 Answer the following two questions related to conversion of native vegetation: Does the project convert :y. acres or more of native vegetation to lawn or landscaped areas? Circle: Yes G Does the project convert 2 Y, acres or more of native vegetation to pasture? Circle: Yes @ Indicate Total Volumes of Proposed: Cut ;:) Fill (cu/yd) lR 1EA ~ E~,rlf1~ \f) Impervious surface is a hard surface that either pr prior to development. A hard surface area which ca from the flow present under natural conditions prior tops, walkways, patios, driveways, parking lots or s and oiled, macadam or other surfaces which similarl ents or tards the entry of water in the soil antle as under natUralconditions es wate ter quan ities or at an increased rate of flow developmUtlf.F ~rOitlpertl"us surface incl ude, b1tm \W ~fflitptiltfn~<t~f , 11' I i ra ~).~rea~r~l'tlil~!f~'BltlIOSVmg;rgrav I roads, p~fVmO~ 1M ~\lf:lI9,lHJJ' m M~o\fiEi'H~tllr<lllnfiltr::Jtlon of stormwater. STORMWATER CALULATIONS -IMPERVIOUS SURFACE NEW EXISTING Structures (all roof area) sq/ft Structures (all roof area) 10/7 sq/ft sq/ft Sidewalks sq/ft sq/ft Patios sq/ft 'If; sq/ft Solid Decks sq/ft (without infiltration below) sq/ft Driveway ~ tJlJ () sq/ft sq/ft Other sq/ft sq/ft Total Existing rO/7 sq/ft 'II, sq/ft 'This amount will be used to check total lot coverage. Sidewalks Patios Solid Decks (without infiltration below) Driveway Other Total New TOTAL NEW + TOTAL EXISTING* The following questions will help determine whether the proposed project is considered development or redevelopment. DEVELOPMENTv.REDEVELOPMENT Does the site have 35% or more of existina impervious surface? Circle: Yes 1. r- % (;) Divide the total existina impervious surface above by the size of the parcel and convert to a percentage: FURTHER INSTRUCTIONS: If the answer is yes, the proposal is considered redevelopment and the attached Figure 2 should be used to determine the applicable Minimum Requirements. If the answer is no, the proposal is considered new development and the attached Figure 1 should be used, At this juncture, the applicant should refer to the applicable Flow Chart to determine the Minimum Requirements for stormwater management. DCD staff will help verify the classification of the project and the application requirements, For proponents of "small", projects who must comply only with Minimum Requirement #2-Construction Stormwater Pollution Prevention-an additional submittal is riot required. The proponent is responsible for employing the 12 Elements to control erosion and prevent sediment and other pollutants from leaving the site during the construction phase of the project. Pick up the Construction Stormwater Pollution Prevention (SWPP) Best Management Practices (BMPs) Packet. Proponents of "medium" projects-those that must meet only Minimum Requirements #1 through #5-and for "large" projects-those that must meet all 10 Minimum Requirements-are required to submit a Stormwater Site Plan. DCD has prepared a submittal template of a Stormwater Site Plan, principally for rural residential projects. Complete the template in the Stormwater Site Plan Instructions and Submittal Template or prepare a Stormwater Site Plan using the step-by-step guidance in the Stormwater Management Manual. APPLICANT SIGNATURE By signing the Stormwater Calculation Worksheet, I as the applicanUowner attest that the information provided herein is true and correct to the best of my knowledge, I also certify that this application is being made with the full knowledge and. consent of all OWlJ:~ 1~~Y"6 (LANDOWNER OR AUTHORIZED REPRESENTATIVE SIGNATURE) (DATE) stormwater calc worksheet doc - REV. 10/1212003 - - - ~ ... &.J....., STORMW A TER PLAN DEe - 8 2006 ;~~ (( ~ IE JIVE D JEFFERSON COUNTY JEFF ~Jft'OtJNTYOPMENT DEPARTMENT OF COMMUNITY DEVEL NT 621 Sheridan Street. Port Townsend. Washington 98368 360/379-4450.360/379-4451 Fax http://www.co.jefferson.wa.us/commdevelopmentl ~HnHSllN I;uurulr UCD Construction Stormwater Pollution Prevention Best Management Practices (BMPs) Packet For "small" projects (as determined through the Stormwater Calculation Worksheet), the applicant shall consider the twelve Construction Stormwater Pollution Prevention elements and implement applicable BMPs. A set of useful BMPs for typical rural residential construction is attached. There is no additional submittal required as part of the permit application. For "medium" and "large" projects, the Construction Stormwater Pollution Prevention Plan (SWPPP) is part of the overall Stormwater Site Plan required as part of the permit application. Refer to the Stormwater Management Information Sheet for guidance. The following twelve elements must be considered for Construction Stormwater Pollution Prevention before and during the construction phase of the project: 1. Mark Clearing Limits 7. 2. Establish Construction Access 8. 3. Control Flow Rates 9. 4. Install Sediment Controls 10. 5. Stabilize Soils 11. 6. Protect Slopes 12. Each of the twelve elements is described in more detail below: Protect Drain Inlets Stabilize Channels and Outlets Control Pollutants Control De-Watering Maintain Best Management Practices Manage The Project 1. Mark Clearing Limits By minimizing the limits of clearing on the site, a builder can minimize stormwater runoff and provide effective control of pollution. 2. Establish Construction Access Much of the sediment that leaves a construction site does so on the wheels of delivery and construction vehicles that drive off a project site. Construction access must be limited to a single location and a properly constructed Stabilized Construction Entrance (BMP C 105) should be included on the site. 3. Control Flow Rates Stormwater that leaves a project site unimpeded may exceed the capacity of the existing stormwater control facilities downstream and may contain sediment that may be deposited as the velocity of the runoff decreases. Stormwater protection on a construction site should include measures to control the flow rate of runoff from the site. This can be done by installing a Sediment Trap (BMP C240) or other measure that will impede the flow of water off a construction site. 4. Install Sediment Controls In addition to limiting the rate of stormwater flow off a construction site, measures should be put in place to treat the runoff and remove sediment. Limiting of the cleared area (Element 1) will assist in this effort, but there will be exposed soils that may move with the runoff. Suggested BMPs for controlling sediment include Straw Bale Barriers (BMPC230), Brush Barrier (BMP C231), Gravel Filter Berm (BMP C232), and Silt Fence (BMP C233). Installation of a Sediment Trap (Element 3) is an additional sediment control feature. construction SWPP.doc Page 1 10/12/2003 STORMWATER PLAN FFERS N COUNTY 5. Stabilize Soils DEPT, OF COMMUNITY DFVH.OPMENT An additional measure that can mini . SIGN JURF: . . I ize soils on the$~fj]fi)\1IH"lt"" '," mulch or some other covering. This will limit the amount of soil that is exposed to rainfall, thuS'lini~itijdW\ ~Jt UNI }jJl.H sediment that could potentially leave the site. BMPs that could be used for this include Mulching (BMP C121), Nets and Blankets (BMP C122), and Plastic Covering (BMP C123). During periods of dry weather dust can become a problem and sediment could be transported from the site in high winds. BMP C140 Dust Control should be followed to limit loss of soils in windy conditions. 6. Protect Slopes If the cleared area includes slopes of 3:1 (Horizontal: Vertical) or steeper, the slopes should be protected to limit runoff. If the slopes are not protected, rills and gullies may form, transporting sediment to the lower elevations and potentially off the construction site. The slopes should be graded to minimize erosion and runoff at the downstream end of the slopes, and runoff should be collected and treated. The following BMPs could be used Surface Roughening (BMP C130), Interceptor Dike and Swale (BMP C200), and Pipe Slope Drains (BMP C204). 7. Protect Drain Inlets Runoff from urban construction sites often discharges into existing stormwater collection systems. Water enters the collection system through drain inlets. If there are drain inlets downstream of a construction site, they should be protected using BMP C220 Storm Drain Inlet Protection. 8. Stabilize Channels and Outlets Any temporary on-site channels or ditches that are used to control runoff should be stabilized to prevent erosion in the channel. BMP C202 Channel Lining and BMP C209 Outlet Protection should be used. 9. Control Pollutants The best way to control pollution is to limit the source of pollution. Construction debris should be maintained in a safe location. Vehicle maintenance on the construction site should be minimized and any spill should be promptly cleaned up. Concrete spillage should be kept to a minimum and cleaning of the concrete trucks after they have unloaded should be done in an area that will not drain off site (see BMP C151 Concrete Handling). 10. Control Dewatering In some cases, excavation for the foundation or below ground structures will encounter ground water. This water must be removed (dewatered) from the excavation. Discharge of this ground water must be treated in a manner that will not cause damage downstream due to flow rates or added pollution. There are no specific BMP identified for this activity, but the water should be handled with care to assure that soils or other pollutants are not added to this flow. 11. Maintain BMPs Installation of the appropriate BMPs is not adequate to completely control stormwater runoff. The BMPs that have been installed on the project must be inspected and maintained during the duration of the construction project. In addition, the temporary controls that were installed for construction should be removed within 30 days of completion of the work. Typically, once construction has been completed, the temporary facilities are not maintained, and by removing the facilities, it will ensure that these won't fail and discharge water or sediment that had been previously trapped or contained. 12. Manage the Project Management of a project has four aspects: 1. Phasing construction to prevent transportation of runoff and sediment, 2. Limiting the work during seasons where large amounts of rainfall could be anticipated, 3. Coordination with Utilities and other Contractors, and 4. Inspection and Monitoring. All of these for aspects are important and must be followed to ensure a project that will have minimal impact on the environment. Volume II of the Manual contains additional BMPs that could be used on-site. The applicant is encouraged to review the Manual to see if other BMPs may be applicable to, or more useful on, a particular site. lRE(~lEr~rTRO construction SWPP,doc Page 2 10/12/2003