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INTER WEST — EVERETT CONTRACTOR'S YARD INTERIM FILL PROJECT Sitts & Hill Engineers, Inc. <br />CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN Job Number 17,733 <br />manent stabilization measures (such as pavement, riprap, gabions, or geotextiles) <br />which will prevent erosion. <br />Design and Installation Specifications <br />Seed retention/detention ponds as required. <br />Install channels intended for vegetation before starling major earthwork and hydroseed <br />with a Bonded Fiber Matrix. For vegetated channels that will have high flows, install <br />erosion control blankets over hydroseed. Before allowing water to flow in vegetated <br />channels, establish 75 percent vegetation cover. If vegetated channels cannot be estab- <br />lished by seed before water flow; install sod in the channel bottom —over hydromulch <br />and erosion control blankets. <br />. Confirm the installation of all required surface water control measures to prevent <br />seed from washing away. <br />. Hydroseed applications shall include a minimum of 1,500 pounds per acre of <br />mulch with 3 percent tackifier. See BMP C 121: Mulching (p.284) for specifications. <br />. Areas that will have seeding only and not landscaping may need compost or meal - <br />based mulch included in the hydroseed in order to establish vegetation. Re -install <br />native topsoil on the disturbed soil surface before application. <br />. When installing seed via hydroseeding operations, only about 113 of the seed actu- <br />ally ends up in contact with the soil surface. This reduces the ability to establish a <br />good stand of grass quickly. To overcome this, consider increasing seed quantities <br />by up to 50 percent. <br />Enhance vegetation establishment by dividing the hydromulch operation into two <br />phases: <br />1. Phase 1- Install all seed and fertilizer with 25-30 percent mulch and tackifier <br />onto soil in the first lift. <br />2. Phase 2- Install the rest of the mulch and tackifier over the first lift <br />Or, enhance vegetation by: <br />1. Installing the mulch, seed, fertilizer, and tackifier in one lift. <br />2. Spread or blow straw over the top of the hydromulch at a rate of 800-1000 <br />pounds per acre. <br />3. Hold straw in place with a standard tackifier. <br />Both of these approaches will increase cost moderately but will greatly improve <br />and enhance vegetative establishment. The increased cost may be offset by the <br />reduced need for: <br />2014 Stormwater Management Manual for Westem Washington <br />Volume 11 - Chapter - Page 279 <br />SITTS & HILL ENGINEERS, INC. 31 <br />TACOMA, WASHINGTON <br />