Reducing the Impact of Stormwater Discharge on Sediment Recontamination

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Stormwater plume carrying particulate and urban runoff to the coastal zone in Southern California ( ER-2537)

Stormwater discharge of contaminants remains a critical challenge for protecting Department of Defense (DoD) investments in sediment cleanup as well as in the prevention of future contaminated sediment liabilities. Stormwater control and treatment is at the nexus of this challenge, spanning virtually every DoD coastal site, and linked to every aspect of regulatory compliance. At DoD sites, concentrations of contaminants of concern in stormwater particulates often exceed sediment cleanup levels. This places the burden on DoD to deal with unregulated discharges and watershed-wide diffuse surface runoffs.

Source control, as part of effective sediment remediation, is emphasized by both the DoD and the Environmental Protection Agency (EPA). EPA’s Risk Management Principles for Contaminated Sediment Sites ( OSWER Directive 9285.6-08)  stress the need to “control sources early” and Navy policy on sediment site investigations and  response actions ( USN 2002) “specifies that the source must be identified and controlled before cleanup.” Source control remains a considerable challenge in part due to the complexity of the sediment sites, the diversity of on- and off-site sources, and the difficulty of controlling non-point (e.g., stormwater, aerial deposition) and point sources (e.g. Combined Sewage Overflows, NPDES discharges).

Given that the cost of remediating DoD sediments is estimated to approach $2 billion, the implications for recontamination at these sites are significant. Identified as a critical investment need in the 2016 Workshop Report, SERDP and ESTCP have begun funding basic research for stormwater assessment and management. This includes new tools for identifying upland sources, tools for following stormwater discharge particulate transport and distribution, and novel systems that integrate stormwater capture and treatment to prevent sediment recontamination.