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s <br /> I <br /> F <br /> F <br /> r <br /> is <br /> stable driving surface and to stabilize any areas that have eroded. <br /> Following construction, these areas shall be restored to pre-construction <br /> f k. condition or better to prevent future erosion. <br /> Perform street cleaning at the end of each day or more often if necessary. <br /> f <br /> i <br /> BMP C120: Temporary and Permanent Seeding <br /> Purpose Seeding reduces erosion by stabilizing exposed soils. A well-established <br /> vegetative cover is one of the most effective methods of reducing erosion. <br /> i <br /> Conditions of Use Use seeding throughout the project on disturbed areas that have reached <br /> final grade or that will remain unworked for more than 30 days. <br /> The optimum seeding windows for western Washington are April 1 <br /> jthrough June 30 and September 1 through October 1. <br /> Between July 1 and August 30 seeding requires irrigation until 75 percent <br /> _: grass cover is established. <br /> Between October l and March 30 seeding requires a cover of mulch with <br /> k straw or an erosion control blanket until 75 percent grass cover is <br /> established. <br /> i Review all disturbed areas in late August to early September and complete <br /> all seeding by the end of September. Otherwise, vegetation will not <br /> establish itself enough to provide more than average protection. <br />( _ Mulch is required at all times for seeding because it protects seeds <br />[ % from heat, moisture loss, and transport due to runoff. Mulch can be <br /> applied on top of the seed or simultaneously by hydroseeding. See <br /> BMP C 121: Mulching for specifications. <br /> R <br /> Seed and mulch, all disturbed areas not otherwise vegetated at final <br /> site stabilization. Final stabilization means the completion of all soil <br /> f ? disturbing activities at the site and the establishment of a permanent <br /> ( = vegetative cover, or equivalent permanent stabilization measures (such <br /> as pavement,riprap, gabions or geotextiles) which will prevent <br /> ¢; erosion. <br /> Design and Seed retention/detention ponds as required. <br /> Installation <br /> Specifrcations Install channels intended for vegetation before starting major <br /> r earthwork and hydroseed with a Bonded Fiber Matrix. For vegetated <br /> channels that will have high flows, install erosion control blankets <br /> over hydroseed. Before allowing water to flow in vegetated <br /> g channels, establish 75 percent vegetation cover. If vegetated <br /> channels cannot be established by seed before water flow; install sod <br /> in the channel bottom—over hydromulch and erosion control <br /> E blankets. <br />� IP <br /> Volume H—Construction Slorn ivaler Pollution Prevention-August 2012 <br /> j P 4-13 <br /> F <br />