About the research

Silt fence has long been used as a means for intercepting and treating construction site stormwater runoff prior to offsite discharge. Standard small-scale testing methodologies for evaluating the filtering component of silt fence installations have failed to mimic realistic flows and sediment loadings commonly placed on such sediment control practices. To address these issues, this study evaluated the performance capabilities of two nonwoven and three woven silt fence geotextiles using an innovative testing methodology and a small-scale testing apparatus. In addition, a stacked sandbag installation was tested to demonstrate proof-of-principle for evaluating three-dimensional practices within the apparatus. The overall intent for conducting the evaluations was to develop a greater understanding of effluent flow rates, sediment retention capabilities, and water quality impacts associated with each practice. Results suggest that sediment-laden flow-through rates of nonwoven geotextiles are on average 43% lower than woven materials, which resulted in extensive upstream retention times for nonwoven materials. Sediment retention results indicate that nonwoven geotextiles have an average sediment retention rate of 97% while woven geotextiles average 91%. These results are similar to the full-scale testing efforts, which reported average sediment retention rates for nonwoven and woven materials as 93% and 88%, respectively. Finally, water quality analyses suggest that the primary means for turbidity reductions rely on the process of sedimentation during the 30-minute test period (i.e., 46% reduction) and filtration during the 90-minute dewatering period (i.e., 19% reduction), which also corresponds to the results of full-scale testing efforts on silt fence installations