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CITY OF EVERETT STORMWATER MANAGEMENT MANUAL <br /> 3. If erosion occurs due to poorly controlled drainage, the problem shall be fixed and the eroded <br /> area protected. <br /> 3.2.10 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 /> 1. Plastic covering may be used on disturbed areas that require cover measures for less than 30 days, <br /> except as stated below. <br /> ' 2. Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively <br /> - rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term (greater than <br /> 6 months) applications. <br /> . 3. Clear plastic sheeting can be used over newly-seeded areas to create a greenhouse eff'ect and <br /> encourage grass growth if the hydroseed was installed too late in the season to establish <br /> 75 percent grass cover, or if the wet season started earlier than normaL Clear plastic should not <br /> be used for this purpose during the summer months because the resulting high teinperatures can <br /> kill the grass. <br /> 4. Due to rapid runoff caused by plastic sheeting,this method shall not be used upslope of areas that <br /> might be adversely impacted by concentrated runof£ Such areas include steep and/or unstable <br /> slopes. <br /> 5. While plastic is inexpensive to purchase, the added cost of installation, maintenance, re�noval, <br /> and disposal can make this an expensive material. <br /> 6. Whenever plastic is used to protect slopes, water collection measures must be installed at the base <br /> of the slope. These measures include plastic-covered berms, channels, and pipes used to covey <br /> clean rainwater away from bare soil and disturbed areas. At no time is clean runoff from a plastic <br /> covered slope to be mixed with dirty runoff from a project. <br /> 7. Other uses for plastic include: <br /> a. Temporary ditch liner <br /> b. Pond liner in temporary sediment pond <br /> • c. Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel <br /> ' being stored <br /> _ d. Emergency slope protection during heavy rains <br /> e. Temporary drainpipe ("elephant trunk")used to direct water. <br /> Design and/nstallation Specifications <br /> 1. Plastic sheeting shall have a minimum thickness of 0.06 millimeters. <br /> 2. If erosion at the toe of a slope is likely, a gravel berm,riprap, or other suitable protection shall be <br /> installed at the toe of the slope in order to reduce the velocity of runoff. <br /> 3. Plastic slope cover must be installed as follows: <br /> a. Run plastic up and down slope, not across slope <br /> b. Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet <br /> Volume 11— Construction Stormwater Pollution Prevention <br /> 3-18 <br />