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ILLINOIS URBAN MANUAL
PRACTICE STANDARD
EROSION BLANKET
(sq ft.)
CODE 830
 (Source: VA Erosion and Sediment Control Handbook) |
DEFINITION
A preformed protective blanket of straw or other plant residue, or plastic fibers formed into a mat, usually with a plastic mesh on one or both sides.
PURPOSE
The purposes of this practice are to protect the soil surface from raindrop impacts and overland flow during the establishment of grass or other vegetation, and to reduce soil moisture loss due to evaporation.
CONDITIONS WHERE PRACTICE APPLIES
This practice applies where the protection of newly seeded areas is critical. This is especially important where flowing water may occur before the grass is established. The most common application for erosion control blankets is in the bottom of small channels and on steep embankments.
CRITERIA
Erosion blankets shall be installed after all top-soiling, fertilizing, liming and seeding is complete.
The blanket shall be in firm contact with the soil. It shall be anchored per the manufacturer’s recommendation with the proper number and spacing of wire staples. The staples shall be the proper width and length to meet the manufacturer’s recommendations.
On slopes and in small drains the blanket shall be unrolled upstream to downstream parallel to the direction of flow. The upstream end of each blanket shall be anchored in a minimum 6-inch deep anchor trench. These blankets, when laid side by side, shall overlap a minimum of 4 inches. When more than one blanket length is needed, the material shall be overlapped 12 inches over the downstream piece. All edges shall be stapled as per manufacturer’s recommendation.
CONSIDERATIONS
Erosion blankets will be located as part of the site development plan. They will protect the ground surface from raindrop impacts and flowing water. They will also retain moisture on seeded areas thus increasing the potential for germination and survival of the vegetation. Erosion blankets materials will break down over time. They should be chosen so that they last long enough for the grass or other vegetation to become established.
PLANS AND SPECIFICATIONS
Plans and specifications for installing erosion blankets shall be in keeping with this standard and shall describe the requirements for applying the practice to achieve its intended purpose. At a minimum include the following items:
All plans shall include the installation, inspection, and maintenance schedules with the responsible party identified.
Standard drawing EROSION BLANKET PLAN IL-530 may be used as the plan sheet.
OPERATION AND MAINTENANCE
Inspect all erosion blankets periodically and after rainstorms to check for damage due to water running under the blanket or if the blankets that have been displaced. Where water has flowed under the blanket, more staples may be needed per given area or more frequent anchoring trenches installed. If significant erosion has occurred under the blanket then reseeding may be needed. Any erosion blankets that have been displaced will need to be put back and re-stapled.
NRCS IL August 1994