Public Works-Storm Water Department
Brian Jenks
101 North Main Street
Room 127
Clinton, TN 37716
865-463-6870

EROSION AND SEDIMENT CONTROL

Eroding construction sites are a leading cause of water quality problems in Tennessee.  A construction site can release up to a dump truck and a half (30 tons) of soil per acre during a large storm event unless proper erosion control practices are incorporated into the site erosion and sediment control plan. According to the State’s 2000 305(b) water quality report, siltation is the largest cause of impairment to water quality in Tennessee streams.  Negative impacts from siltation currently impact 4,164 stream miles and 2,686 lake acres in Tennessee.

All land disturbing activities which result in changes to the land by grading, filling, excavating, removal or placement of topsoil, trees, or vegetative covering shall be undertaken with due care to control or eliminate soil erosion and sedimentation.  Under no circumstances are land development activities allowed to increase erosion from any particular site due to inadequately installed or maintained erosion control structures.  The materials needed to control erosion are easy to find and relatively inexpensive to purchase and install.  Commonly used materials employed for erosion control include silt fence, rock, geo-textiles, slope drains, grass seed, straw bales, and mulch. 

GENERAL REQUIREMENTS FOR EROSION AND SEDIMENT CONTROL

1.                   Phased Construction:  Land shall be developed in increments of workable size so that adequate controls can be installed and maintained during the construction period.  Operations shall be staged so that the area being developed is not exposed for a long period of time without stabilization and so that the first disturbed areas are completely controlled before the next section is opened.  Appropriate control measures shall be installed before the start of land disturbing activities.

2.                   Preservation and Re-establishment of Vegetation:  Preserving or re-establishing vegetative cover is the most effective form of erosion control.  Temporary or permanent vegetation should be planted as soon as possible on all denuded areas.  Non-vegetative cover such as straw, mulch, wood chips, or erosion control matting may be used to control erosion during the poor growing season.  Stockpiles and excavated soil piles should be covered with waterproof cover (e.g. tarp).  If stockpiles are to be left uncovered for more than 30 days, they should be seeded with temporary seed such as annual rye or winter wheat.  Tennessee Department of Environment and Conservation regulations require that temporary vegetation be planted on sites that will be idle for more than 30 days 

3.                   Provisions shall be made to accommodate the increase in runoff resulting from changes to the soil and surface conditions during development.  Sediment basins or stilling basins should be incorporated to let sediment settle out of the storm water runoff before being discharged.  Discharge velocity shall be controlled to prevent erosion and sedimentation immediately downstream from the point of discharge.  Energy dissipating structures/devices (e.g. check dams or rip-rap) shall be incorporated into the drainage system as necessary. 

4.                   Construction Site Entrance:  Construction site entrances need to be installed to prevent from leaving the site.  A gravel construction entrance built to the specifications outlined in the TDEC Sediment and Erosion Control Manual.

5.                   Sediment Barriers: Sediment barriers function as leaky dams causing muddy water to pool behind them and allow the sediment to settle out before the water drains through the barrier.  A single row of silt fence is needed for every 100 ft of slope length.  Install silt fence on down slope sites of the site parallel to the contour of the land.  Two rows of Type C silt fence should be installed along creeks and streams with a minimum of 6 ft between rows.  A 25 ft buffer should be maintained from stream or creek banks on each side.  If possible a natural vegetative buffer should be maintained along creek banks.  Consult the TDEC Sediment and Erosion Control Manual for silt fence specifications and proper installation requirements.

6.                   Sediment Cleanup:  Soil tracked into roads or off the site must be cleaned up daily.

7.                   Inspection and Maintenance:  Sediment and erosion control structures must be inspected at least once a week and within 24 hours of a storm event. Documentation of the weekly inspections should be maintained onsite.  Any repairs or modifications should be completed as soon as possible to ensure that the functionality of the structures remains intact.