1515 132ND ST SE 2022-01-20 - Laserfiche WebLink

BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and dis- turbed areas. Conditions of Use Plastic covering may be used on disturbed areas that require cover measures for less than 30 days, except as stated below. . Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: 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 upslope of 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. . 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 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. 2. Pond liner in temporary sediment pond. 3. Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored. 4. Emergency slope protection during heavy rains. 5. Temporary drainpipe ("elephant trunk") used to direct water. 2014 Stormwater Management Manual for Westem Washington Volume II - Chapter 4 - Page 294