December 2008
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Clear Water Alabama Field Day Highlights Erosion and Sediment Control Practices Used on Construction Sites


Field Day participants sit atop one of the bottomless culverts at the Tannehill Preserve subdivision. Such culverts allow for construction above creeks and streams without disturbing them.



The Alabama Erosion and Sediment Control Partnership held the 2008 Clear Water Alabama Field Day in Bessemer. The field day highlighted many erosion and sediment control practices and gave participants a chance to observe and discuss many practices on-site, including new sediment basin technology to reduce the suspension of soil particles in water, called turbidity.

Two of the demonstration sites, the Colonial Promenade Shopping Center of Bessemer and Tannehill Preserve subdivision, showcased bottomless culverts, an innovation aimed at allowing construction of roads over creeks and streams without having to alter or destroy the ecosystem of that creek or stream. Tannehill Preserve also demonstrated a low-impact planned urban development designed to preserve wildlife habitats as well as soil and water quality through practices like stream buffers, narrower streets and sidewalks on only one side of the road.

The field day also exhibited a new sediment basin for construction sites, the first of its kind built in Alabama. The basin includes baffles, a skimmer and chemical treatment with polyacrylamide. The basin’s components slow the flow of the water, promote rapid settling of the fine soil particles that otherwise stay in suspension for days and discharge the water from the surface rather than the bottom of the basin. The end result is clearer, cleaner water leaving the basin.


The sediment basin at the Cedar Creek subdivision construction site in Bessemer is shown at near capacity after the heavy rainfall from Tropical Storm Fay. The difference is turbidity becomes visible as the water passes through the basin’s baffles from left to right.


The basin was installed at the Cedar Creek subdivision in Bessemer just days before Tropical Storm Fay brought heavy rainfall to the area.

"The basin performed perfectly," said Natural Resources Conservation Service State Conservation Engineer Perry Oakes. "Turbidity levels were reduced over 95%. The new sediment basin technology will be introduced into the Alabama Handbook for Erosion Control and Stormwater Management on Construction Site soon. Look for these type basins to be constructed on construction sites throughout Alabama."

The Clear Water Field Day demonstrations were presented by representatives from private firms working in erosion and sediment control as well as presenters from the Alabama Department of Transportation, Auburn University, the Alabama Soil and Water Conservation Committee, and the Natural Resources Conservation Service.