Reducing the Impact of Stormwater Discharge on Sediment Recontamination
Stormwater management is a continuing challenge at all Department of Defense (DoD) facilities. Stormwater discharges are regulated under federal and state permits yet are implicated as a major cause of contamination of sediment near discharge points at or close to DoD sites. Regulators and local communities are applying increasing pressure on coastal DoD facilities to further protect water bodies by reducing the magnitude and concentration of industrial site chemicals being discharged in stormwater runoff. Conversely, for facilities in arid regions, stormwater is viewed as a “lost” freshwater resource. Opportunities for water beneficial reuse to supplement diminishing supplies exist if adequate pollutant removal can be achieved.
SERDP recognized the nexus of need and opportunity for stormwater management in the 2016 Workshop Report. Ongoing research investments are geared toward monitoring tools and improving best management practices (BMPs) to reduce contaminant loads to water bodies, passive treatment systems to minimize or prevent sediment contamination, while critically examining these systems for opportunities to provide for freshwater harvest and beneficial reuse. A description of these ongoing and recently completed projects is provided below.
Low Impact Development/Best Management Practices
Mr. Gary Anguiano and his team from the U.S. Naval Facilities Engineering and Expeditionary Warfare Center demonstrated and validated a Low Impact Development/Best Management Practice (LID/BMP) passive stormwater treatment system at the U.S. Naval Base Point Loma in San Diego. The LID/BMP system treated water from an industrial facilities area that contained high levels of metals, oil and grease, and total suspended solids. Stormwater was channeled first to the LID and passed downward through a pre-treatment filter gabion, drought-tolerant vegetation, a composite biofiltration soil media, and gravel. Water passing through the LID then passed to a media filter BMP consisting of bone char and activated alumina. The project demonstrated the effectiveness of the LID/BMP through 16 separate stormwater events and was able to achieve below discharge limits for copper, zinc, oil and grease, and total suspended solids. ( Project Overview)
Ms. Heidi Howard of the U.S. Army Corps of Engineers Engineer Research and Development Center developed and demonstrated a Stormwater Management Optimization Toolbox. The modeling tool is specifically designed to help DoD facilities achieve compliance with regulatory stormwater requirements, optimizing runoff management and infiltrations with properly sized BMP solutions at the lowest practicable cost. The toolbox was assessed over varying climates and regions at several installations across the country. ( Project Overview)
Dr. Dick Luthy and his team at Stanford University are advancing stormwater BMPs for pollution control, with a goal of treating the water to levels to allow harvest and reuse. The targeted sites for these BMPs are at DoD facilities in arid regions. To date, the project has been identifying and testing combinations of activated carbon and other geomedia in column studies to determine the optimal combinations to be deployed in a field demonstration. Also, this work will identify the optimal size and flow design of the BMP. Dr. Luthy and his team have developed a novel and innovative way to create “synthetic” stormwater using stormwater catch-basin sediments from DoD sites. Chemicals of interest being targeted include metals, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and per- and polyfluoroalkyl substances (PFAS). The outcome from this work is anticipated to be a demonstrated BMP at a DoD installation as well as development of a guidance manual for improved stormwater control measures using these LID/BMP systems. ( Project Overview)
- At Oregon State University, Dr. Staci Simonich and her team are evaluating stormwater treatment technologies to control contaminants, preventing sediment recontamination and potentially beneficial reuse. The targeted DoD installations would be in areas of higher rainfall, such as those experienced in the Pacific Northwest. Treatment train systems are being tested in the laboratory utilizing native northwest plants, activated carbon, and commercially available stormwater sorbents. The chemicals of interest being targeted include metals, PCBs, PAHs, and PFAS. Dr. Simonich and her team plan to use the results from field trials, to update and validate the Environmental Protection Agency’s (EPA’s) Stormwater Management Model (SWMM). This model will aid the design of future LID/BMPs through the simulation of the hydrologic, hydraulic, and contaminant fate and transport processes. ( Project Overview)
- Dr. Birthe Kjellerup and her team at the University of Maryland are developing innovative treatment media for use in stormwater LID/BMPs. The objective of this work is to pinpoint media that would not only capture metals and other persistent organic pollutants (POPs), but also facilitate microbial degradation of the sequestered PCBs and PAHs. An emphasis of this research is to identify sustainable sources of the treatment geomedia that will facilitate and promote the microbial communities needed to degrade the POPs. ( Project Overview)
Monitoring and Modeling Tools for Stormwater Control
- Dr. Danny Reible and his team at Texas Tech University are testing and demonstrating new methods to identify contaminant levels and total mass discharge to coastal receiving waters. In an initial project, Dr. Reible and his team showed that contaminant loads discharging in stormwater at Naval Base San Diego are directly associated with larger (sand-size) particulates; conventional understanding is that contaminants are associate with finer (silt-clay) particles. ( Project Overview) The innovative methods and findings from the initial project will be used in this follow on research to develop tools to directly inform the selection of stormwater controls as LID, BMPs, or hybrid LID/BMPs. The analytical tools and model will be applied to the hybrid LID/BMP at U.S. Naval Base Point Loma in San Diego. An important addition to these tools will be an analytical method to identify whether the contaminants measured in the larger particle fractions are in microplastics, such as tire fragments. ( Project Overview)
- At the U.S. Naval Information Warfare Center (NIWC)–Pacific, Ms. Molly Colvin and her team are deriving an environmentally relevant method for stormwater toxicity testing for National Pollution Discharge Elimination System (NPDES) permits at DoD sites. Under current permits, methods developed to assess continuous point source discharges are now also being applied to episodic discharges, such as stormwater, dry dock discharges, and ballast water. These procedures have been criticized by the science community for failing to use exposures relevant to the intermittent, or episodic, nature of these events, instead using continuous static exposures. The NIWC team developed testing methods relevant to stormwater episodic events and are in the process of validating those methods. Federal and state regulators, as well as the user-community, are actively engaged in the test development and validation procedure. Ms. Colvin and her team plan to develop guidance on using/incorporating these episodic methods into NPDES permits. ( Project Overview)