Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: July 9, 2000
Publication Date: July 9, 2000
Interpretive Summary: Billions of tons of valuable topsoil are lost each year in the United States as a result of soil erosion. When sediment reaches a stream or lake it can decrease water quality and harm aquatic life. Drastically disturbed lands, such as construction sites for roads and buildings, are particularly vulnerable to soil erosion. Silt fences are one method of capturing and retaining sediment on-site. Little information is presently known about ho silt fences perform when exposed to sediment-laden flows. This study examined the performance of silt fences exposed to both clear water and sediment-laden flows. The sediment can plug the openings in the silt fence and substantially decrease the amount of water that passes the fabric. This information should be of interest to the wide range of disciplines charged with reducing soil erosion, minimizing sediment runoff, and improving water quality.
Research on silt fences has been conducted to evaluate their effectiveness at separating sediment from runoff water. Two woven silt fence fabrics were exposed to a range of flow rates and sediment feed rates. Changes in water surface elevation against the fabric were measured using an electronic water level recorder. The head information was used to determine the flow rate exiting the fabric by calculating the volumetric changes during the recession period of each test. Head versus discharge plots were developed to compare clear water and sediment-laden flows. Clear water flows were similar for the two fabrics, and the sediment-laden flow appeared to have little affect on fabric A (open weave fabric). Fabric B (tight weave fabric), however, exhibited dramatic changes between clear water and sediment-laden flows, suggesting that the sediment blocked openings in the fabric. The trapping efficiencies, average sediment concentrations passing the fabric, and particle sizes passing the fabric were also examined. This study provides valuable information about silt fence performance.