One of the greatest problems for specifiers in achieving NPDES sediment reduction goals is the lack of quantifiable criteria for the performance of available Best Management Practices (BMPs). The effectiveness of the many different types of sediment control BMPs, including silt fence and other sediment retention devices (SRDs), has not been adequately quantified. There are little performance data available for most SRDs because there has been no recognized standard test procedure for measuring relevant performance criteria. SRD material components can be accurately evaluated for hydraulic properties using the bench-scale standard test method, ASTM D 5141, “Standard Test Method for Determining Filtering Efficiency and Flow Rate of the Filtration Component of a Sediment Retention Device Using Site-Specific Soil”. Yet, the effectiveness of many SRDs is system or installation dependent, therefore a large-scale test that can incorporate full-scale “as installed” conditions is the ideal evaluation procedure. Recently these needs have been addressed with the issuance of a large-scale standard test method ASTM D 7351, “Standard Test Method for Determination of Sediment Retention Device Effectiveness in Sheet Flow Applications.” The test method quantifies both sediment removal and associated flow rate thru an SRD, so that the potential for either excessive sediment loss or the back-up of runoff can be assessed.
This paper details both the bench-scale and the large-scale test procedures and presents data on tests run on a variety of silt fence styles to demonstrate the ability of standardized testing to differentiate product performance and, in so doing, to enable a specifier to “engineer” the system to provide the desired balance between flow and sediment retention.
Key words: SRDs, sediment control, NPDES, performance testing, specifications
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