Using compost-based erosion control products is a best management practice (BMP), as compost bonds tightly with soil, leaving no gap between soil and cover, which means less opportunity for water to run underneath and undermine the protection. These products are highly effective at removing certain contaminants from runoff, such as oil, diesel and other hydrocarbons.
Types of Products
- Compost Blanket. A layer of loosely applied compost placed on the soil in disturbed areas to reduce storm water runoff and erosion. It is typically applied using a blower truck, but could be applied by hand. The compost fills in small rills and voids to limit channelized flow, absorb water, and provide a more permeable surface to facilitate storm water infiltration. If rapid revegetation is the goal, gardeners can mix seeds into the compost before application.
- Compost Filter Sock. A mesh tube filled with composted materials that landscapers can place perpendicular to sheet-flow runoff to control erosion and retain sediment in disturbed areas. Depending on the particle size of the filter medium within the mesh tube, landscapers and contractors can either use them to reduce heavy flows and trap sediment or to remove pollutants from urban runoff. Compost filter socks are proven effective at removing gasoline, diesel and oil residues from runoff. Filter socks come in 5”, 8” and 12” diameters, and can either be purchased on pallets or made on site using the mesh and a blower truck.
- Mulch. Ground woody materials that are good for protecting relatively flat surfaces from wind and rain. Mulch absorbs some water, and as it breaks down gradually adds organic matter to the soil, increasing storm water infiltration and biological life. On steeper slopes, it may run off with sheet flow. Finely ground mulch can be blown into filter socks and used as a high-flow sediment trap. If used in this way, the mulch should be pathogen reduced first.
- Living Wall. Vertical spaces covered by live vegetation that are also known as green walls or biowalls. Gardeners can use piles of seeded compost socks retained by wire mesh to create a retaining wall, which then grows plants. These may be placed along creeks to reduce bank erosion, along highways to keep sheet flow and sediments off the road, or even in parks and other applications.
Types of Applications
Highways and Roads
- CalTrans Erosion Control Toolbox. Overview of erosion treatments by slope, benefit and cost:
- Innovative use of compost by state highway departments across the United States
- Use of compost along highways in Texas
- Use of compost to stabilize steep slopes and prevent erosion and sediment control
- Historical Caltrans Erosion Control manual
Fire-Damaged Lands. Use of compost products on fire-damaged lands.
Low Impact Development
- California Water Boards, Guidance for Design and Construction of Vegetated Low Impact Development Projects
- Vegetated filter strips
- Vegetated swales
- Infiltration basins
Construction Sites. State of California Department of Transportation: Construction Site Best Management Practice (BMP).
- CalRecycle vineyard erosion control demonstration project (Napa, Sonoma)
- CalRecycle vineyard erosion and nutrient demonstration project (Napa)
Research and Case Studies
- CalRecycle sponsored research on compost blanket impact on runoff water quality from fire scarred land
- Compost blankets along highways research by Iowa State University
- Research on compost socks:
- Environmental Protection and Enhancement with Compost
- Stormwater Management Methods and Opportunities for Compost Use
- Compost use on fire site--Interview with CalRecycle engineer Todd Thalhamer
- American Society of State Highway and Transportation Officials, U.S. Army Corps of Engineers, USDA-NRCS, USEPA: Federal Specifications for Compost Filter Socks for Sediment and Erosion Control
- USCC: Caltrans specification document
- California Stormwater Quality Association (CASQA)