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1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />PENSKE TRUCK LEASING EVERETT ONSITE IMPROVEMENTS <br />CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN <br />Sitts & Hill Engineers, Inc. <br />Job Number 17,710 <br />Table II-4.1.8 Mulch Standards and Guidelines (continued) <br />Mulch <br />Quality <br />Application <br />Remarks <br />Material <br />Standards <br />Rates <br />high length <br />oa�ridth <br />ratio. <br />BMP C122: Nets and Blankets <br />Emsioftvntrol nets and blankets are intended to prevent erosion and hold seed and <br />mulch in ce on steep slopes and in channels so that vegetation can become well <br />established. addition, some nets and blankets can be used to permanently reinfo <br />turf to protect d . age ways during high flows. Nets (commonly called matting) a <br />strands of materia oven into an open, but high -tensile strength net (for exam , <br />coconut fiber matting lankets are strands of material that are not tightly w en, but <br />instead form a layer of i docking fibers, typically held together by a bi radable or <br />photodegradable netting ( example, excelsior or straw blankets). T generally have <br />lower tensile strength than ne but cover the ground more compl y. Coir (coconut <br />fiber) fabric comes as both nets d blankets. <br />Conditions of Use <br />Erosion control nets and blankets should used: <br />. To aid permanent vegetated stabilizatio f opes 21-1:1 V or greater and with more <br />than 10 feet of vertical relief. <br />. For drainage ditches and swales (hi y reco nded). The application of appro- <br />priate netting or blanket to draina ditches and les can protect bare soil from <br />channelized runoff while vege on is established. is and blankets also can cap- <br />ture a great deal of sedime ue to their open, porous cture. Nets and blankets <br />can be used to permane y stabilize channels and may p vide a cost-effective, <br />environmentally pre le altemative to riprap. 100 percent nthetic blankets <br />manufactured for in ditches may be easily reused as tempo ditch liners. <br />Disadvantages of b kets include: <br />. Surface p aration required. <br />. On sl s steeper than 2.51-1:1V, blanket installers may need to be roped a har- <br />ne ed for safety. <br />' hey cost at least $4,000-6,000 per acre installed. <br />vantages of blankets include: <br />2014 Stonnwater Management Manual for Westem Washington <br />Volume Il - Chapter 4 - Page 288 <br />SITTS & HILL ENGINEERS, INC. 38 <br />TACOMA, WASHINGTON <br />