Department of Defense (DoD) facilities may release a variety of particulate-bound and dissolved contaminants with stormwater discharges. Of particular interest here are those contaminants that are associated with settleable particles that can result in recontamination of near-field bed sediments in receiving waters. That sediment recontamination can lead to negative impacts on the receiving waters and sediment and also limit the recovery or effectiveness of remediation efforts in those sediments.

The objective of this project is to gain a better understanding of how stormwater Best Management Practices (BMPs) can influence the physical and chemical characteristics of DoD stormwater loads to receiving waters and thereby affect the potential for sediment recontamination. This understanding will be used to adapt the existing modeling tools developed for Naval bases around the United States as their main stormwater quality modeling engine, leading to a planning tool that can be used to support the evaluation of BMPs at these bases based on a quantitative assessment of implementation cost versus reduction in sediment recontamination risk (i.e., cost-benefit analysis).

The technical objective of this research is to evaluate the performance of stormwater BMPs in terms of their potential for reducing sediment recontamination risk. The performance evaluation will consider the mass and particulate strength (or contaminant concentration per mass of suspended sediment) of size segregated contaminant loads of Naval base stormwater discharges, and the change in toxicity and sediment recontamination risk resulting from various practical, cost-effective BMP implementation scenarios. Site-specific stormwater pollutant fractionation data at several DoD bases will be used to validate the WinSLAMM (Source Loading and Management Model for Windows) model for that base and extend it to size fractionated stormwater load prediction. This model will then be used to develop a family of related spreadsheet tools specific to DoD operations at several locations.

Existing WinSLAMM modeling efforts have focused on specific metals commonly of concern for stormwater, and are not designed to provide size segregated stormwater contaminant load predictions. By expanding the model to size segregated stormwater contaminant loads and expanding the contaminant understanding to other common sediment contaminants (including those often responsible for sediment toxicity, such as PAHs), the model can then be used to evaluate specific management strategies to directly compare cost and effectiveness in terms of preventing (or significantly delaying or reducing the likelihood of) the occurrence of sediment recontamination. (Anticipated Project Completion - 2023). 

Hussain, T., D. Athanasiou, B. Rao, M. Bejar, M. Rakowska, I. Drygiannaki, D.B. Chadwick, M.A. Colvin, N.T. Hayman, G.H. Rosen, M. Otto, B. Steets, R. Pitt, and D. Reible. 2023. Sediment Recontamination Potential and Biological Impacts of Hydrophobic Organics from Stormwater in a Mixed-use Watershed. Science of The Total Environment, 906:167444. doi.org/10.1016/j.scitotenv.2023.167444.