HomeMy WebLinkAboutElement 5 BPM-C123BMP C123: Plastic Covering
Purpose Plastic covering provides immediate, short-term erosion protection to
slopes and disturbed areas.
Conditions of
Use
x Plastic covering may be used on disturbed areas that require cover
measures for less than 30 days, except as stated below.
x 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.
x Clear plastic sheeting can be used over newly-seeded areas to create a
greenhouse effect and encourage grass growth if the hydroseed was
installed too late in the season to establish 75 percent grass cover, or if
the wet season started earlier than normal. Clear plastic should not be
used for this purpose during the summer months because the resulting
high temperatures can kill the grass.
x Due to rapid runoff caused by plastic sheeting, this method shall not be
used upslope of areas that might be adversely impacted by
concentrated runoff. Such areas include steep and/or unstable slopes.
x While plastic is inexpensive to purchase, the added cost of installation,
maintenance, removal, and disposal make this an expensive material,
up to $1.50-2.00 per square yard.
x Whenever plastic is used to protect slopes, water collection measures
must be installed 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. At no time is clean
runoff from a plastic covered slope to be mixed with dirty runoff from
a project.
x 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; and,
5. Temporary drainpipe (“elephant trunk”) used to direct water.
4-26 Volume II – Construction Stormwater Pollution Prevention February 2005
Design and
Installation
Specifications
x Plastic slope cover must be installed as follows:
1. Run plastic up and down slope, not across slope;
2. Plastic may be installed perpendicular to a slope if the slope length
is less than 10 feet;
3. Minimum of 8-inch overlap at seams;
4. On long or wide slopes, or slopes subject to wind, all seams should
be taped;
5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench
at the top of the slope and backfill with soil to keep water from
flowing underneath;
6. Place sand filled burlap or geotextile bags every 3 to 6 feet along
seams and pound a wooden stake through each to hold them in
place;
7. Inspect plastic for rips, tears, and open seams regularly and repair
immediately. This prevents high velocity runoff from contacting
bare soil which causes extreme erosion;
8. Sandbags may be lowered into place tied to ropes. However, all
sandbags must be staked in place.
x Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
x If erosion at the toe of a slope is likely, a gravel berm, riprap, or other
suitable protection shall be installed at the toe of the slope in order to
reduce the velocity of runoff.
Maintenance
Standards
x Torn sheets must be replaced and open seams repaired.
x If the plastic begins to deteriorate due to ultraviolet radiation, it must
be completely removed and replaced.
x When the plastic is no longer needed, it shall be completely removed.
x Dispose of old tires appropriately.
February 2005 Volume II – Construction Stormwater Pollution Prevention 4-27