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i BMP C123: Plastic Covering Purpose , Plastic covering provides immediate, short-term erosion protection to slopes and dis- turbed areas. I Conditions of Use Plastic covering may be used on disturbed areas that require cover measures for less I than 30 days, except as stated below. . Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: 1 The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term (greater than six months)applications. . Due to rapid runoff caused by plastic covering, do not use this method u slo a of p p areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. . Plastic sheeting may result in increased runoff volumes and velocities, requiring additional on-site measures to counteract the increases. Creating a trough with , wattles or other material can convey clean water away from these areas. . To prevent undercutting,trench and backfill rolled plastic covering products. I . While plastic is inexpensive to purchase, the added cost of installation, main- tenance, removal, and disposal make this an expensive material, up to $1.50-2.00 per square yard. . Whenever plastic is used to protect slopes install water collection measures at the base of the slope. These measures include plastic-covered berms, channels, and 1 pipes used to covey clean rainwater away from bare soil and disturbed areas. Do not mix clean runoff from a plastic covered slope with dirty runoff from a project. . Other uses for plastic include: 1. Temporary ditch liner. 1 2. Pond liner in temporary sediment pond. 3. Liner for bermed temporary fuel storage area if plastic is not reactive to the 1 type of fuel being stored. 4. Emergency slope protection during heavy rains. I 5. Temporary drainpipe ("elephant trunk") used to direct water. 1 2014 Stormwater Management Manual for Western Washington Volume II- Chapter 4 -Page 294