United States
Environmental Protection
Agency
tormwater Best Management Practice
ompost Blanket
NPDES
Minimum Measure
Construction Site Stormwater Runoff Control
Subcategory
Erosion Control
Purpose and Description
A compost blanket is a layer of loosely applied composted
material placed on the soil in disturbed areas to reduce
Stormwater runoff and erosion. This material fills in small rills
and voids to limit channelized flow, provides a more permeable
surface to facilitate Stormwater infiltration, and promotes
revegetation. Seeds can be mixed into the compost before it
is applied. Composts are made from a variety of feedstocks,
including yard trimmings, food residuals, separated municipal
solid waste, and municipal sewage sludge (biosolids).
Controlling erosion protects water quality in surface waters,
such as streams, rivers, ponds, lakes, and estuaries; and
increasing Stormwater infiltration replenishes groundwater
aquifers. Applying a compost blanket also works well as a
Stormwater best management practice (BMP) because it:
• Retains a large volume of water, which aids in establishing
vegetation growth within the blanket,
• Acts as a cushion to absorb the impact energy of rainfall,
which reduces erosion,
• Stimulates microbial activity that increases the
decomposition of organic matter, which increases nutrient
availability and improves the soil structure,
• Provides a suitable microclimate with the available nutrients
for seed germination and plant growth, and
• Removes pollutants such as heavy metals, nitrogen,
phosphorus, fuels, grease and oil from Stormwater runoff,
thus improving downstream water quality (USEPA 1998).
Applicability and Limitations
Compost blankets can be placed on any soil surface: flat, steep,
rocky, or frozen. The blankets are most effective when applied
on slopes between 4:1 and 1:1 (horizontal run:vertical rise);
such as construction sites, road embankments, and stream
Figure 1. Applying a
compost blanket on a
bare and eroding slope
Figure 2. Same slope
after revegetation
banks; where Stormwater runoff can occur as sheet flow. On
the steeper slopes (1:1) the compost blanket should be used in
conjunction with netting or other confinement systems to further
stabilize the compost and slope, or the compost particle size
and depth should be specially designed for this application.
Compost blankets should not be placed in locations that receive
concentrated or channeled flows either as runoff or a point
source discharge. If compost blankets are placed adjacent to
highways and receive concentrated runoff from the traffic lanes,
they should be protected by compost berms, or a similar BMP
that diffuses or diverts the concentrated runoff before it reaches
the blanket (Glanville, Richard, and Persyn 2003). Because a
compost blanket can be applied to the ground surface without
having to be incorporated
into the soil, it provides
excellent erosion and
sediment control on difficult
terrain, such as steep or
rocky slopes (Figures 3, 4).
Projects where the cost of
transporting and applying
composts is most easily
justified are situations that
demand both immediate
erosion control and growth
of vegetative cover, such as
projects completed too late
in the growing season to
establish natural vegetation
before winter or areas with
poor quality soils that don't
readily support vegetative
growth (Glanville, Richard,
and Persyn 2003).
Figure 3. Applying a compost blanket on
a steep, rocky slope
Figure 4. Same slope after revegetation
Office of Water, 4203M
www.epa.gov/npdes/pubs/compostblankets.pdf
www.epa.gov/npdes/stormwater/menuofbmps
EPA833-F-11-007
March 2012
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Stormwater Best Management Practice: Compost Blankets
What Is Compost?
Compost is the product of controlled biological decomposition
of organic material that has been sanitized through the
generation of heat and stabilized to the point that it is beneficial
to plant growth. It is an organic matter resource that has the
unique ability to improve the biological, chemical, and physical
characteristics of soils or growing media. Compost contains
plant nutrients but is typically not characterized as fertilizer
(USCC 2008).
This decomposition of organic material is produced by
metabolic processes of microorganisms. These microbes
require oxygen, moisture, and food in order to grow and
multiply. When these three factors are maintained at optimal
levels, the natural process of decomposition is greatly
accelerated. The microbes generate heat, water vapor, and
carbon dioxide as they transform the raw materials into a
stable soil conditioner.
Compost can be produced
from many raw organic
materials, such as leaves,
food scraps, manure, and
biosolids. However, the
mature compost product
bears little physical
resemblance to the raw
material from which it
originated.
Figure 5. Mature compost product
How Is Compost Beneficial?
Biological Benefits
Provides an excellent substrate for soil biota. The activity
of soil microorganisms is essential for productive soils and
healthy plants. Their activity is largely based on the presence
of organic matter. Soil microorganisms include bacteria,
protozoa, and fungi. They are not only found within compost,
but will also proliferate within the soil under a compost blanket.
These microorganisms play an important role in organic matter
decomposition, which leads to humus formation and nutrient
availability. Some microorganisms also promote root activity;
specific fungi work symbiotically with plant roots, assisting them
in extracting nutrients from the soils.
Suppresses plant diseases. The incidence of plant diseases
may be influenced by the level and type of organic matter
and microorganism present in soils. Research has shown that
increased populations of certain microorganisms may suppress
specific plant diseases, such as pythium blight and fusarium wilt.
Chemical Benefits
Provides nutrients. Compost blankets contain a considerable
variety of macro- and micronutrients essential for plant growth.
Since compost contains relatively stable sources of organic
matter, these nutrients are supplied in a slow-release form.
Modifies and stabilizes pH. The pH of composts differ. When
necessary, a compost may be chosen that is most appropriate
for revegetating a particular construction site.
Physical Benefits
Improved soil structure and moisture management.
In fine-textured soils (i.e., clay or clay loam), the addition of
compost will increase permeability, and reduce stormwater
runoff and erosion. The soil-binding properties of compost are
due to its humus content. Humus is a stable residue resulting
from a high degree of organic matter decomposition. The
constituents of humus hold soil particles together, making them
more resistant to erosion and improving the soil's ability to hold
moisture.
Effectiveness of Compost, Topsoil,
and Mulch
Because of the biological, chemical, and physical benefits
it can provide, compost makes a more effective erosion
control blanket than topsoil. An Iowa State University study
(Glanville, Richard, and Persyn 2003), sponsored by the Iowa
Department of Natural Resources and Iowa Department of
Transportation (DOT), compared the quantity of runoff from
road embankments treated with topsoil and with compost
blankets. The test plots were exposed to simulated, high
intensity rainfall (3.7 inches/hour) lasting for 30 minutes. Results
showed that the amount of runoff from the embankment treated
with a compost blanket was far less than the runoff from the
embankment treated with topsoil.
Mulch is a protective covering placed around plants for
controlling weeds, reducing evaporation, and preventing roots
from freezing. It is made of various substances usually organic,
such as hardwood or pine bark. A compost blanket is a much
more effective BMP for erosion control and revegetation than
mulch. A University of Georgia research study (Faucette and
Risse 2002) reported that correctly applied compost blankets
provide almost 100 percent soil surface coverage, while other
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Stormwater Best Management Practice: Compost Blankets
methods (e.g., straw mats and mulches) provide only 70 to
75 percent coverage. Uniform soil coverage is a key factor
in effective erosion and sediment control because it helps
maintain sheet flow and prevents stormwater from forming rills
under the compost blanket.
Compost Quality
Compost Properties
Maturity. Maturity indicates how well the compost will support
plant growth. One maturity test measures the percent of seeds
that germinate in the compost compared to the number of
seeds that germinate in peat based potting soil. For example,
if the same number of seeds was planted in the potting soil
(control) and in a marketed compost product, and 100 of them
germinate in the potting soil and 90 germinate in the compost,
the compost's maturity would be 90 percent. Another maturity
test compares the growth and vigor of seedlings after they have
been growing in both compost and potting soil.
Stability. Stability determines how "nice" the compost is.
While microbial decay is actively transforming the feedstocks
into compost, the unstable mixture may have unpleasant
characteristics such as odors. However, after the decay
process is completed, the stable compost product no longer
resembles the feedstock or has offensive characteristics.
During the composting process, C02 is produced because the
microbes are actively respiring. So the microbial respiration
(C02 evolution) rates can be measured and used to determine
when the microbial decay is completed and the compost
product has stabilized.
Presence of Pathogens. The pathogen count indicates
how sanitary the compost is. EPA has defined processes for
composting biosolids that reduce the number of pathogenic
organisms to nondetectible levels and ensure the resulting
compost will be sufficiently heat treated and sanitary. These
processes to further reduce pathogens (PFRP) are defined
in 40 CFR, Part 503, Appendix B, Section B. Compost
quality specifications often require compost to be treated
by a PFRP process, so there are no measurable pathogenic
microorganisms present.
Other compost properties that may be found in compost
quality specifications are plant nutrients and heavy metal
concentrations, pH, moisture content, organic matter content,
soluble salts, and particle size.
Compost Quality Testing
A compost testing, labeling, and information disclosure
program, the Seal of Testing Assurance Program, has been
established by the United States Composting Council (USCC),
a private, nonprofit organization. Under this program testing
protocols for determining the quality and condition of compost
products at the point of sale have been jointly approved and
published by the USCC and U.S. Department of Agriculture.
These Test Methods for Evaluating Compost and Composting,
the TMECC Testing Protocols are conducted by independent
laboratories to help compost producers determine if their
compost is safe and suitable for its intended uses, and to
help users compare various compost products and verify the
product safety and market claims. The goal of the program
is to certify the compost products have been sampled and
tested in accordance with these approved protocols. Compost
producers who participate in this program have committed
to having their products tested by an approved laboratory
according to the prescribed testing frequency and protocols
and to providing the test results to anyone upon request. The
products of participating compost producers carry the USCC
certification logo and product information label.
Compost Quality Specifications
The Federal Highway Administration supported developing
specifications for compost used in erosion and sediment
control through a cooperative agreement with the Recycled
Materials Resource Center at the University of New Hampshire.
The original compost blanket specifications (Alexander 2003)
were developed under this grant. Working with the USCC and
Ron Alexander (Alexander 2003), the American Association
of State Highway and Transportation Officials finalized and
approved these specifications (AASHTO 2010), which include:
narrative criteria (e.g., no objectionable odors or substances
toxic to plants), numerical specifications [e.g., pH, soluble salts,
moisture content, organic matter content, particle size, stability,
and physical contaminants (e.g., metal, glass, plastics)], and
pathogen reduction using the EPA processes to further reduce
pathogens. These AASHTO specifications also recommend
the TMECC testing protocols. A number of states have now
developed specifications for the compost they use in erosion
and sediment control. Examples are the California DOT
specifications and Texas DOT specifications.
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Stormwater Best Management Practice: Compost Blankets
Compost Blanket Installation
Once any trash and debris have been removed from a site, a
compost blanket can be uniformly applied usually between
1 and 3 inches thick using a bulldozer, skid steer, manure
spreader, or hand shovel. Application rates (thickness) are
often included in compost blanket specifications. The compost
blanket should extend at least 3 feet over the shoulder of the
slope to ensure that stormwater runoff does not flow under the
blanket (Alexander 2003). On very rocky terrain or if the slope
is too steep for heavy equipment, a pneumatic blower truck is
needed to apply the compost (Figure 6). If the slope is steep,
a compost blanket may work best in conjunction with other
BMPs, such as compost socks placed across the slope to
reduce the runoff
velocity (Figure 7)
or compost berms
placed at the top
of the slope to
divert or diffuse
concentrated runoff
before it reaches
the compost
Figure 6. Using a pneumatic blower truck to apply blanket (Figure 8).
a compost blanket on a rocky 7:7 slope
Figure 7. Using compost socks
to reduce the runoff velocity
Figure 8. Using a compost berm
to divert or defuse highway runoff
before it reaches the compost
blanket
Fabric netting can also be used to hold the compost blanket
on steep slopes (Figure 9). The netting is usually stapled to the
slope (Figure 10), and then the compost is blown on the slope
and into the netting.
Mature compost for erosion control on moderate slopes is shown
in Figure 11, with a red pen for size comparison. The compost in
Figure 9. Netting stabilizing
a compost blanket
Figure 10.
Stapling
netting to
the slope
Figure 5 is too fine for erosion
control. Coarser compost
should be avoided on slopes
that will be landscaped or
seeded, as it will make planting
and crop establishment
more difficult. But coarse
and/or thicker compost is
recommended for areas with
higher annual precipitation or
Figure 11. Compost for erosion
control on moderate slopes
rainfall intensity, and even coarser compost is recommended for
areas subject to wind erosion (Alexander 2003).
Grass, wildflower, or native plant seeds appropriate for the soil
and climate can be mixed into the compost. Although seed
can be broadcast on the compost blanket after installation, it
is typically incorporated into the compost before it is applied,
to ensure even distribution of the
seed throughout the compost
and to reduce the risk of the
seed being washed from the
surface of the compost blanket by
stormwater. Wood chips may also
be added to reduce the erosive
effect of rainfall's impact energy. Figure 12. impact of rainfall
Inspection and Maintenance
The compost blanket should be inspected periodically and
after each major rainfall. If areas of the compost blanket have
washed out, another layer of compost should be applied.
In some cases, it may be necessary to add another BMP to
control the stormwater, such as a compost filter sock or silt
fence. On slopes greater than 2:1, establishing thick, permanent
vegetation as soon as possible is the key to successful erosion
and sediment control. Restricting or eliminating pedestrian
traffic on such areas is essential (Faucette and Ruhlman 2004).
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Stormwater Best Management Practice: Compost Blankets
Climate Change Mitigation
References
In 2005 an estimated 246 million tons of municipal solid
wastes were generated in the United States. Organic materials
including yard trimmings, food scraps, wood waste, paper and
paper products are the largest component of our trash and
make up about two-thirds of the solid waste stream. When this
organic matter decomposes in landfills, the carbon is converted
to methane (CH4) and other volatile organic compounds, which
are released into the atmosphere and contribute to global
warming. EPA has identified landfills as the single largest
source of methane, a potent greenhouse gas that is 23 times
more efficient at trapping heat than carbon dioxide (C02).
Landfills contribute approximately 34 percent of all man-made
methane released into the atmosphere in the United States
(USEPA 2007). Two approaches for mitigating climate change
are reducing carbon emissions and sequestering carbon in the
atmosphere.
Reducing carbon
emissions. When
organic materials are
composted and then
recycled, the composting
feedstocks are diverted
from already burdened
municipal landfills,
and landfill-generated
methane gas emissions
are reduced.
Figure 13. As compost like this is recycled,
green house gasses are reduced
Sequestering Carbon. Carbon sequestration is the act of
removing carbon dioxide from the atmosphere and storing it
in carbons sinks, such as oceans, plants and other organisms
that use photosynthesis to convert carbon from the atmosphere
into biomass. Forest ecosystems and permanent grasslands
are prime examples of
terrestrial carbon sinks
that sequester carbon.
We no longer have the
vast expanses of prairies
and eastern forests, but
we are using compost
blankets to revegetate
construction sites, road
banks, and green roofs;
AASHTO 2010. Standard Practice for Compost for Erosion/
Sediment Control (Compost Blankets). R 52-10. Washington,
DC: American Association of State Highway and Transportation
Officials.
www.epa.gov/npdes/pubs/aashto.pdf
Alexander, R. 2003. Standard Specifications for Compost
for Erosion/Sediment Control, based on work supported by
the Federal Highway Administration under a Cooperative
Agreement with the Recycled Materials Resource Center at the
University of New Hampshire, Durham, New Hampshire.
www.alexassoc.net/organic_recylcing_composting_documents/
standard_compost_erosion_sediment_control_specs.pdf
Faucette, Britt, and Mark Risse 2002. "Controlling Erosion with
Compost and Mulch." BioCycle June: 26-28.
www.epa.gov/npdes/pubs/biocycle2002.pdf
Faucette, Britt, and Melanie Ruhlman 2004. "Stream Bank
Stabilization Utilizing Compost." BioCycle January: 27.
www.epa.gov/npdes/pubs/biocycle2004.pdf
Faucette, L.B., C.F. Jordan, L.M. Risse, M. Cabrera. D.C.
Coleman, L.T. West 2005. "Evaluation of Stormwater from
Compost and Conventional Erosion Control Practices in
Construction Activities." Journal of Soil and Water Conservation
60: 288-297. Available from J. Soil & Water Con. abstract free
and full text for a fee.
Faucette, L.B., L.M. Risse, C.F. Jordan, M.L. Cabrera, D.C.
Coleman, L.T. West 2006. "Vegetation and Soil Quality Effects
from Hydroseed and Compost Blankets Used for Erosion
Control in Construction Activities." Journal of Soil and Water
Conservation 61: 355-362. Available from J. Soil & Water Con.
abstract free and full text for a fee.
Faucette, L.B., J. Governo, C.F. Jordan, B.G. Lockaby, H.F.
Carino, R. Governo 2007. "Erosion Control and Storm Water
Quality from Straw with PAM, Mulch, and Compost Blankets of
Varying Particle Sizes." Journal of Soil and Water Conservation
62: 404-413. Available from J. Soil & Water Con. abstract free
and full text for a fee.
Figure 14. Compost blankets will nurture
revegetation, which sequesters carbon and
prevents erosion
and this vegetation
sequesters carbon.
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Stormwater Best Management Practice: Compost Blankets
Faucette, L.B. 2008. "Performance and Design for Compost
Erosion Control and Compost Storm Water Blankets."
Proceedings of the International Erosion Control Association
Annual Conference. Orlando, Florida: International Erosion
Control Association. Abstract available from IECA.
Faucette, L.B., B. Scholl, R. E. Bieghley, J. Governo. 2009.
"Large-Scale Performance and Design for Construction Activity
Erosion Control Best Management Practices." Journal of
Environmental Quality 38: 1248-1254. Available from J. Env.
Qual. Abstract and full text free.
www.soils.org/publications/jeq/abstracts/38/3/1248
Filtrexx 2009. Filtrexx International's Carbon Reduction &
Climate Change Mitigation Efforts. Item # 3324. Grafton, OH:
Filtration International, LLC.
Glanville, Tomas D., Tom L. Richard, Russell A. Persyn 2003.
Impacts of Compost Blankets on Erosion Control. Revegetation.
and Water Quality at Highway Construction Sites in Iowa. Ames:
Iowa State University of Science and Technology, Agricultural
and Biosystems Engineering Department.
www.eng.iastate.edu/compost/papers/FinalReport_Apri!2003_
ExecSummary.pdf
Risse, M., L.B. Faucette. 2009. Compost Utilization for Erosion
Control. Bulletin No. 1200. Athens: University of Georgia,
Cooperative Agriculture Extension Service.
USCC 2001. Compost Use on State Highway Applications.
This is a series of case studies as well as model specifications
developed by state DOTs for using compost in highway
construction projects. Ronkonkoma, NY: U.S. Composting
Council. Available from USCC for a fee.
http://compostingcouncil.org/publications/
USCC 2008. USCC Factsheet: Compost and Its Benefits.
Ronkonkoma, NY: U.S. Composting Council.
http://compostingcouncil.org/admin/wp-content/
uploads/2010/09/Compost-and-lts-Benefits.pdf
USEPA 1998. An Analysis of Composting as an Environmental
Remediation Technology. EPA530-R-98-008. Washington, DC:
U.S. Environmental Protection Agency, Office of Solid Waste
and Emergency Response.
www.epa.gov/osw/conserve/rrr/composting/pubs/
USEPA 2007. Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-2005. USEPA 430-R-07-002. Washington, DC:
U.S. Environmental Protection Agency, Office of Atmospheric
Programs.
www.epa.gov/climatechange/emissions/downloads06/07CR.pdf
Websites
Caltrans 2010. Compost Blanket. California Department of
Transportation.
www.dot.ca.gov/hq/LandArch/ec/organics/compost_blanket.htm
USEPA 2010. Compost Based Stormwater Best Management
Practices Webinars. U.S. Environmental Protection Agency,
Region 5, Chicago.
www.epa.gov/region5/waste/solidwaste/compost/webinars.html
Photograph Credits
Figures 1, 2. Barrio Cogburn, Texas DOT
Figures 3, 4. Dwayne Stenlund, CPESC Minnesota DOT
Figure 5. Larry Strong, affiliation unknown
Figure 6. Scott McCoy, KSS Consulting, LLC
Figure 7. Tom Glanville, Iowa State University
Figure 8. Jason Giles, CPESC, Rexius
Figures 9, 10. Britt Faucette, CPESC, Filtrexx International, LLC
Figure 11. Jason Giles, CPESC, Rexius
Figure 12. Larry Beran, Texas A&M University
Figures 13, 14. Jami Burke, CESCL, Cedar Grove Landscaping and
Construction Services
Disclaimer
Please note that EPA has provided external links because they provide additional information that may be useful or interesting. EPA cannot attest to the
accuracy of non-EPA information provided by these third-party websites and does not endorse any non-government organizations or their products or services.
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