Laserfiche WebLink
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 effect 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 temperatures 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 runoff. Such areas include steep and/or unstable <br />slopes. <br />I <br />5. While plastic is inexpensive to purchase, the added cost of installation, maintenance, removal, <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 Installation 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 ll — Construction Stormwater Pollution Prevention <br />3-18 <br />