My Erosion Control Failed: How Bad Is It? Sediment Characterization and Forensic Wetland Delineation

Stormwater management and erosion control are important requirements of the federal Clean Water Act. Section 401 requires compliance with water quality requirements. Section 402 requires that all construction sites on an acre or greater of land, as well as municipal, industrial and commercial point source discharges obtain permission under the National Pollutant Discharge Elimination System (NPDES) permit. Section 404 prohibits dredge and fill discharges without a Corps permit and appropriate compensatory mitigation. If erosion control measures fail and sediment is released into Waters of the US, including wetlands, there may be a violation of all three of these sections of the Clean Water Act as well as comparable state standards. If such a failure occurs, how do you decide if a release of sediment should be remediated? Or would it be better left in place to prevent further damage to sensitive streams and wetlands from clean-up activities? This paper will present a technique for quantifying and documenting released sediment that is explicit and repeatable. It can be used as a basis for discussion of the severity of the release with regulatory agencies, to plan and prioritize remediation, and to demonstrate remediation success. The techniques presented will include soil characterization from sediment sources and depositions, line intercept sampling, replicated samples, and incorporation of GPS and GIS to document findings. Because these methods are explicit and repeatable, objective criteria can be defined to demonstrate remediation success. Use of the same techniques before and after sediment remediation provides a means to demonstrate successful sediment restoration and removal. When sediment is released into wetlands, a forensic wetland delineation is necessary to determine the extent of impact. Basic principles of wetland delineation and forensic wetland delineation will be presented with a discussion of integration with sediment characterization methods.