Full-Scale Performance Evaluations of Innovative and Manufactured Sediment Barrier Practices

Abstract

Sediment barriers (SB) are devices typically installed along the perimeters of construction sites to intercept, capture, and contain pollutant discharge. Effective SBs minimize sediment transportation off-site by temporarily impounding stormwater and facilitating sediment capture upstream of the installation. Full-scale experiments were conducted on common, innovative, and manufactured SB practices used within the construction industry to better understand their performance. These practices consisted of two manufactured silt fence systems, three sediment retention barrier practices, and three manufactured sediment barrier products. Installation details for each practice were analyzed and amendments made to provide the most effective installations. Test observations indicated that a major failure mode of innovative and manufactured SB practices was flow bypass due to undermining. Performance-based comparisons of sediment retention rates, maximum impoundment depths, effluent flow rates, and treatment efficiencies were determined for each practice. Longevity tests were also conducted to evaluate characteristic changes over iterative storm events. Overall performance evaluations indicate practices that achieve impoundment depths greater than 1 ft (0.3 m) have consistent sediment capture rates of at least 90%. More importantly, impoundment depths greater than 1.5 ft (0.46 m) do not facilitate improved sediment capture rates. These observations suggest that optimized sediment capture is achieved when a SB practice has an effective upstream impoundment depth between 1 and 1.5 ft (0.3 and 0.46 m). Additionally, impoundment depths within this optimal zone reduce impoundment surface turbidity up to 60% when compared with turbidity levels along the bottom of the impoundment.