Erosion, sediment and Runoff control for Roads and Highways
http://www.epa.gov/OWOW/NPS/education/runoff.html
LLS. Environmental Protection Agency
Office of Water
United States
Environmental Protection
Agency
Office of Water
(4503F)
EPA-841-F-95-008d
December 1995
Erosion, Sediment, and Runoff Control for Roads
and Highways
r
The Coastal Zone Management Act of 1972 established a program for states to voluntarily develop
comprehensive programs to protect and manage coastal water resources. There are now 29 coastal states
and territories with federally approved coastal management programs.
The Coastal Zone Act Reauthorization Amendments (CZARA) of 1990 specifically charged coastal states
and territories with upgrading their runoff pollution control programs to protect coastal waters. The
Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration
(NO AA) jointly oversee the development and implementation of these Coastal Nonpoint Pollution
Control Programs, or CNPCPs.
EPA published Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal
Waters to be used by states to implement management measures - economically achievable measures that
reflect the greatest degree of runoff pollution control - to control the addition of runoff pollutants to
coastal waters.
The Guidance also includes best management practices, technologies, processes, siting criteria, and
operating methods for roads, highways, and bridges that states can use to implement the management
measures. States can use alternative management measures if they provide the same or a greater degree of
pollutant control as the management measures in the Guidance. States will begin implementing their
CNPCPs in 1996 and achieve full implementation by 2004.
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CZARA applies to site development and land disturbing activities in the coastal management area of each
State with an approved coastal management program. Certain road, highway and bridge related activities
are excluded from this program due to coverage under the National Pollutant Discharge Elimination
System (NPDES) permitting program These activities include construction activities where 5 or more
acres (2.02 ha) are disturbed, and activities within municipalities with municipal separate storm sewer
systems that have populations of 100,000 or more
Why Runoff Control is Needed
Runoff controls are essential to preventing polluted runoff from roads, highways, and bridges from
reaching surface waters Erosion during and after construction of roads, highways, and bridges can
contribute large amounts of sediment and silt to runoff waters, which can deteriorate water quality and
lead to fish kills and other ecological problems.
Heavy metals, oils, other toxic substances, and debris from construction traffic and spillage can be
absorbed by soil at construction sites and carried with runoff water to lakes, rivers, and bays Runoff
control measures can be installed at the time of road, highway, and bridge construction to reduce runoff
pollution both during and after construction. Such measures can effectively limit the entry of pollutants
into surface waters and ground waters and protect their quality, fish habitats, and public health.
Pesticides and fertilizers used along roadway rights-of-way and adjoining land can pollute surface waters
and ground water when they filter into the soil or are blown by wind from the area.where they are applied
Table 1 shows typical pollutants in runoff waters that can be traced to the operation of roads and
highways.
Principles of Runoff Control for Roads, Highways, and Bridges
Preventing runoff pollution from road, highway, and bridge construction in coastal areas requires planning,
education, inspection, and maintenance. An erosion and sediment control (ESC) plan that incorporates the
most appropriate and cost-effective best management practices (BMPs) is essential to effective pollution
control Affected highway personnel must be educated about the requirements of the ESC plan Inspection
and enforcement authority are necessary to ensure awareness of and compliance with the adopted
practices. Finally, BMPs require regular maintenance to ensure that they perform optimally The following
principles apply to an effective erosion and runoff control program.
• Develop a comprehensive erosion and sediment control (ESC) plan prior to earth-moving
activities. Write ESC requirements into plans, specifications, and cost estimates for highway and
bridge projects.
Four key factors affect the potential for soil erosion from a site: soil characteristics, vegetative
cover, topography, and climate. Take all of these factors into consideration to develop an ESC plan
that will minimize soil loss, limit the area exposed to construction, maximize the vegetative cover,
use natural topographic features to the best advantage, and include BMPs suitable to the regional
climate
The Federal Highway Administration Local Transportation Assistance Program, the Association of
American State Highway and Transportation Officials, and many state highway departments can
provide ESC guidelines.
• Apply ESC practices to prevent excessive onsite damage. Use ESC BMPs to control the flow of
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runoff water and thereby prevent or lessen soil erosion. Limiting land disturbance and preserving
natural vegetation are excellent ESC practices.
• Apply perimeter control practices to protect the disturbed area from offsite runoff and to
prevent sedimentation damage to areas below the construction site. A sediment and runoff
barrier surrounding the disturbed area prevents construction site runoff from moving offsite and
fouling surface waters downstream
• Keep runoff velocities low and retain runoff on the site. The erosive power of runoff increases
dramatically as distance and slope increase. BMPs can be used to effectively control runoff velocity
and detain it to remove 80 to 90 percent of the sediment from runoff
• Stabilize disturbed areas immediately after final grade has been attained. Any exposed soil is
subject to erosion from rainfall, wind, and vehicles BMPs to stabilize soil should be applied as
quickly as possible after the land is disturbed Temporary stabilization practices include seeding,
mulching, and erosion control blankets or mats.
• Develop a schedule and implement a comprehensive inspection and maintenance program.
This principle is vital to the success of erosion control. BMPs must receive regular inspection and
maintenance to ensure that they are operating effectively and optimally, both during and after
construction
•
Best Management Practices
CZARA defines management measures as economically achievable measures to control the addition of
pollutants to our coastal waters. Management measures are achieved by the application of one or more
BMPs. The BMPs described below are especially useful for erosion and runoff control for roads,
highways, and bridges.
Best management practices can be organized by the function they perform. General maintenance BMPs
(listed below) are usually vegetative practices used to contain polluted runoff from the operation of
highways or from erosion and sedimentation generated at small construction sites A variety of practices
are used at construction sites to control both erosion and polluted runoff. These are identified as
Construction Site BMPs. Practices developed as permanent erosion and sediment control devices are both
structural and nonstructural. Several of these BMPs are listed below as long-term or Permanent Control
BMPs
Construction Site BMPs
• Straw bale barriers should be bound, entrenched, and securely anchored to prevent deterioration
A row of straw bales slows runoff flow and creates a pond behind the barrier where sediment can
settle out Straw bale barriers are most effective for filtering low to moderate storm flows, where
structural strength is not required
• Filter fabrics are engineering fabrics designed to retain sediment particles larger than a certain size
and allow water to pass through. Filter fabrics can be used in silt fences (see below) or erosion
control mats Erosion control mats protect soil and seed from erosion and can be designed to allow
vegetation to grow through the material
• Silt fences are vertical fences of filter fabric that are stretched across and attached to support poles
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The fabric retains sediment on the construction site and allows relatively sediment-free water to pass
through Silt fences are placed to protect streams and surrounding property from sediment-laden
runoff.
• Sediment basins are ponds created by excavation or the construction of a dam or barrier Sediment
basins primarily serve to retain or detain runoff to allow excessive sediment to settle out during
construction Sediment basins can be converted into permanent detention ponds or wetlands after
construction.
• Stabilized entrances reduce the amount of sediment carried off a construction site by vehicles
when pressure-washed on-site. These entrances are designed to include stabilized pads of aggregate
underlain with a filter fabric. Stabilized construction site entrances should be located at any point in
the construction zone where vehicles enter and leave Wheels and undercarriages of vehicles should
be washed before leaving the site.
Operation and Maintenance
Inspection and maintenance of erosion and sediment control BMPs after construction has been completed
is important to ensure that the BMPs are operating properly and effectively Some key operation and
maintenance procedures include:
• Prepare and adhere to a schedule of regular maintenance for temporary erosion and runoff
control BMPs. Two critical maintenance operations that must be performed regularly are cleaning
out accumulated sediment and replacing worn-out or deteriorated materials, such as silt fence
fabrics, so that the effectiveness of the controls is maintained. Maintenance can include dredging and
reshaping sediment basins and revegetating the slopes of grassed swales.
• Remove temporary BMPs from construction areas when they are no longer needed and
replace them, where appropriate, with permanent BMPs.
• Schedule and periodically inspect and maintain permanent erosion and runoff controls. This
should include a periodic visual inspection of permanent BMPs during runoff conditions to ensure
that the controls are operating properly. Clean, repair, and replace permanent erosion and runoff
control BMPs when necessary.
General Maintenance BMPs
• Seeding with grass, and fertilizing to promote strong growth provide long-term stabilization of
exposed surfaces. Disturbed areas can be seeded and fertilized during construction and after it is
completed. Sufficient watering and refertilizing 30 to 40 days after the seeds germinate help
establish dense growth.
• Seeding with grass and overlaying with mulch or mats is done to stabilize cleared or freshly
seeded areas Types of mulches include organic materials, straw, wood chips, bark or other wood
fibers, or decomposed granite and gravel. Mats are made of natural or synthetic material and are
used to temporarily or permanently stabilize soil.
• Wildflower cover has been successfully used by many state and county highway departments to
provide attractive vegetation along roadways and erosion control Careful consideration must be
given to visibility, access, soil condition, climate, and maintenance when choosing sites for
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wildflower cover.
• Sodding with established grass blankets on prepared soil provides a quick vegetative cover to
lessen erosion Proper watering and fertilizing are important to ensure the vitality of newly placed
sod
Permanent Control BMPs
• Grassed swales are shallow, channeled grassed depressions through which runoff is conveyed The
grass in swales slows the flow of runoff water, which allows sediment to settle out and water to
infiltrate into the soil. Grassed swales can remove small amounts of pollutants such as nutrients and
heavy metals Check dams (see below) can be added to grassed swales to further reduce flow
velocity and promote infiltration and pollutant removal
• Filter strips are wide strips of vegetation located to intercept overland sheet flows of runoff They
can remove organic material, sediment, and heavy metals from runoff. Filter strips can consist of any
type of dense vegetation from woods to grass but they cannot effectively treat high-velocity flows
They are therefore best suited to low-density developments.
• Terracing breaks a long slope into many flat surfaces where vegetation can become established
Small furrows are often placed at the edge of each terraced step to prevent runoff from eroding the
edge Terracing reduces runoff velocity and increases infiltration
• Check dams are small temporary dams made of rock, logs, brush, limbs, or another durable
material, placed across a swale or drainage ditch. By reducing the velocity of storm flows, sediment
in runoff can settle out and erosion in the swale or ditch is reduced
• Detention ponds or basins temporarily store runoff from a site and release it at a controlled rate to
minimize downstream flooding. Pollutant removal effectiveness is quite good for well-designed
basins Effectiveness is greatest for suspended sediments (80 percent or more removal) and related
pollutants such as heavy metals.
• Infiltration trenches are shallow, three to eight feet deep (.91 to 2.44 m), excavated trenches that
are backfilled with stone to create underground reservoirs Runoff is diverted into the trenches, from
which it percolates into the subsoil. Properly designed infiltration trenches effectively remove
sediment from runoff and can remove some other runoff pollutants
• Infiltration basins are relatively large, open depressions produced by either natural site topography
or excavation. When runoff enters an infiltration basin, the water percolates through the bottom or
the sides and the sediment is trapped in the basin. The soil where an infiltration basin is built must be
permeable enough to provide adequate infiltration. Some pollutants other than sediment are also
removed in infiltration basins
• Constructed wetlands are areas inundated by water for a sufficient time to support vegetation
adaped for life in saturated soil conditions Wetlands effectively filter sediment, nutrients, and some
heavy metals from runoff waters.
Table 1. Typical pollutants found in runoff from roads and highways.
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http //www epa gov/OWOW/NPS/education/runoff html
Sources of Pollution in Highway Runoff
I! Pollutant
Sedimentation
Nutrients
Heavy Metals
Hydrocarbons
Particulates
Nitrogen &
phosphorus
Lead
Zinc
Iron
Copper
Cadmium
Chromium
Nickel
Manganese
Cyanide
Sodium, calcium &
chloride
Sulphates
Petroleum
Source
Pavement wear, vehicles, the atmosphere and
maintenance activities
Atmosphere and fertilizer application
Leaded gasoline from auto exhausts and tire wear
Tire wear, motor oil and grease
Auto body rust, steel highway structures such as
bridges and guardrails, and moving engine parts
Metal plating, bearing and brushing wear, moving
engine parts, brake lining wear, fungicides &
insecticides
Tire wear and insecticide application
Metal plating, moving engine parts and brake lining
wear
Diesel fuel and gasoline, lubricating oil, metal
plating, bushing wear, brake lining wear and asphalt
paving
Moving engine parts
Anti-caking compounds used to keep deicing salt
granular
Deicing salts
Roadway beds, fuel and deicing salts
Spills, leaks, antifreeze and hydraulic fluids and
asphalt surface leachate
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Erosion, sediment and Runoff control for Roads and Highways
http //www epa gov/OWOW/NPS/education/runoff html
Adapted from Guidance Specifying Management Measures for Sources of Nonpoint Pollution
in Coastal Waters
Homepage
OWOW Homepage
OW-GENERAL@epamail. epa.gov
Revised February 14, 1997
URL: http://www.epa.gov/OWOW/NPS/education/runofT.html
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