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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Erosion, sediment and Runoff control for Roads and Highways                                http //www epa gov/OWOW/NPS/education/runoff htmj


      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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Erosion, sediment and Runoff control for Roads and Highways                                http //www epa gov/OWOW/NPS/education/runoff html


            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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Erosion, sediment and Runoff control for Roads and Highways                                http //www epa gov/OWOW/NPS/education/runoff html


            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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Erosion, sediment and Runoff control for Roads and Highways                                 http //www epa gov/OWOW/NPS/educalion/runoff html


            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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Erosion, sediment and Runoff control for Roads and Highways
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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