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1 <br /> I <br /> 1 <br /> BMP C120: Temporary and er nent Seeding <br /> Purpose <br /> Seeding reduces erosion by stabilizing exposed soils. A well-established vegetative <br /> cover is one of the most effective methods of reducing erosion. <br /> Conditions of Use <br /> Use seeding throughout the project on disturbed areas that have reached final grade or <br /> ' that will remain unworked for more than 30 days. <br /> The optimum seeding windows for western Washington are April 1 through June 30 and <br /> 1 September 1 through October 1. <br /> Between July 1 and August 30 seeding requires irrigation until 75 percent grass cover is <br /> established. <br /> ' Between October 1 and March 30 seeding requires a cover of mulch with straw or an <br /> erosion control blanket until 75 percent grass cover is established. <br /> IReview all disturbed areas in late August to early September and complete all seeding <br /> by the end of September. Otherwise, vegetation will not establish itself enough to <br /> ' provide more than average protection. <br /> . Mulch is required at all times for seeding because it protects seeds from heat, mois- <br /> ture loss, and transport due to runoff. Mulch can be applied on top of the seed or <br /> simultaneously by hydroseeding. See BMP C121: Mulching (p.284)for spe- <br /> cifications. <br /> . Seed and mulch, all disturbed areas not otherwise vegetated at final site sta- <br /> bilization. Final stabilization means the completion of all soil disturbing activities at <br /> Ithe site and the establishment of a permanent vegetative cover, or equivalent per- <br /> 2014 Stormwater Management Manual for Western Washington <br /> Volume II- Chapter 4 -Page 278 <br />