“Stormwater Impacts to Sediments at Naval Bases: A DoD Perspective” by Ms. Amy Hawkins

Sediment contamination is a significant liability for the Department of Defense (DoD), with overall costs estimated at approximately $2 billion. The Navy currently has over 200 sediment sites with remediation of these sites representing approximately 35% of the Navy’s environmental restoration budget. At some sites, the Navy is required to conduct sediment remediation prior to achieving source control or addressing contaminant loading rates that are above sediment cleanup levels. Urban and industrial harbors and rivers are susceptible to ongoing contaminant loading from stormwater in addition to permitted discharges and upstream sites that have not yet been remediated. Recent SERDP and ESTCP projects have focused on improving understanding of ongoing, low-level contaminant flux to aquatic sediments to establish a linkage between loading rate and surface sediment recontamination which can slow or even reverse remediation. Understanding contaminant releases from various sources, developing monitoring and modeling tools to assess loading rates and their effect on downstream surface sediment concentrations, and how to incorporate remedy resilience in the face of ongoing sources are priorities for the Navy.

“Assessing Sediment Recontamination due to Stormwater” by Dr. Danny Reible

Cleanup at contaminated sediment sites is often initiated before land-based sources have been fully identified and controlled. Under such conditions, remediated sites can become recontaminated by continued inputs. Stormwater discharges contain high levels of solids-associated contaminants of concern. One challenge is to measure the contaminant characteristics of stormwater that are relevant to evaluating sediment recontamination. Estimates of stormwater loading and concentrations can be determined for metals and organic contaminants as a function of particle size (i.e., settling characteristics). Receiving waters can be monitored for depositing sediment and the contaminant concentrations on that sediment. Contaminant availability of the depositing sediments can be assessed using bioassays or chemical measurements that relate to availability (e.g., passive porewater sampling). In addition, modeling can be used to extrapolate to conditions beyond those assessed during the monitoring period. Modeling can predict long-term stormwater loads and sediment recontamination beyond the monitoring period. This combined approach to assessing stormwater recontamination of sediments was tested in a demonstration watershed, Paleta Creek at Naval Base San Diego. Results will be discussed with a focus on measurements that are most useful to evaluating sediment recontamination as a result of stormwater releases.

Ms. Amy Hawkins is a Biologist in the Technology Applications Branch of the NAVFAC Engineering and Expeditionary Warfare Center (EXWC). She has supported the Navy's Environmental Restoration Program efforts in risk assessment, sediment remediation, optimization, and green and sustainable remediation (GSR) by providing project reviews and technical consultation. Ms. Hawkins led the effort to finalize the Department of the Navy Environmental Restoration Program (NERP) Manual in 2018. She is the chairperson for the NAVFAC Sediment Workgroup, which has recently developed a white paper on sustainable sediment remediation and is coordinating with development of the addition of sediment related metricks to SiteWise. She is also the chairperson for the NAVFAC Optimization Workgroup. During her time with the group they produced the Navy's GSR Guidance and participated in the development of SiteWise 3. She has previously served as PI or Co-PI on seven SERDP/ESTCP projects, primarily focused on sediment remediation and risk assessment.

Dr. Danny Reible is a Donovan Maddox Distinguished Engineering Chair at Texas Tech University. His research is focused on the fate, transport and management of contaminants in the environment and the sustainable management of water resources. He has authored or edited six books and more than 190 journal articles and book chapters. As a principal investigator, he has obtained research support totaling more than $35 million. He is a Board Certified Environmental Engineer, a Professional Engineer in Louisiana and in 2005 was elected to the National Academy of Engineering for the development of widely-used approaches for the management of contaminated sediments. He holds a doctoral degree in chemical engineering from the California Institute of Technology.