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BMP C123: Plastic Covering <br /> Purpose <br /> Plastic covering provides immediate,short-term erosion protection to slopes and disturbed areas. <br /> Conditions of Use <br /> Plastic covering may be used on disturbed areas that require cover measures for less than 30 days, <br /> except as stated below. <br /> • Plastic is particularly useful for protecting cut and fill slopes and stockpiles. However,the rel- <br /> atively rapid breakdown of most polyethylene sheeting makes it unsuitable for applications <br /> greater than six months. <br /> • Due to rapid runoff caused by plastic covering, do not use this method upslope of areas that <br /> might be adversely impacted by concentrated runoff. Such areas include steep and/or <br /> unstable slopes. <br /> • Plastic sheeting may result in increased runoff volumes and velocities, requiring additional on- <br /> site measures to counteract the increases. Creating a trough with wattles or other material <br /> can convey clean water away from these areas. <br /> . To prevent undercutting,trench and backfill rolled plastic covering products. <br /> . Although the plastic material is inexpensive to purchase,the cost of installation, maintenance, <br /> removal, and disposal add to the total costs of this BMP. <br /> . Whenever plastic is used to protect slopes, install water collection measures at the base of the <br /> slope.These measures include plastic-covered berms,channels,and pipes used to convey <br /> clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a <br /> plastic covered slope with dirty runoff from a project. <br /> • Other uses for plastic include: <br /> • Temporary ditch liner. <br /> • Pond liner in temporary sediment pond. <br /> • Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel <br /> being stored. <br /> • Emergency slope protection during heavy rains. <br /> • Temporary drainpipe("elephant trunk")used to direct water. <br /> Design and Installation Specifications <br /> Plastic slope cover must be installed as follows: <br /> 1. Run plastic up and down the slope, not across the slope. <br /> 2. Plastic maybe installed perpendicular to a slope if the slope length is less than 10 feet. <br /> 2019 Stormwater Management Manual for Western Washington <br /> Volume 11-Chapter 3-Page 298 <br />