By Christopher GardnerJune 24, 2019
The U.S. Army Corps of Engineers, Baltimore District is teaming up with the University of Maryland, Baltimore County, U.S. Geological Survey and other federal partners to learn more about how complex chemical contaminants behave in the environment to help inform future cleanup efforts.
These man-made chemicals, generally referred to as per- and polyfluoroalkyl substances or PFAS, are commonly found in various products all over the world, particularly in products where things are not meant to adhere to certain things or stain.
The PFAS study effort is being funded by a grant through the Strategic Environmental Research and Development Program (SERDP), which is DoD's environmental science and technology program. SERDP is a partnership with the Department of Energy and the EPA and works with numerous other federal and non-federal organizations.
"They're compounds that are both hydrophobic and oleophobic, meaning they resist both water and oils. So, they're really useful and they're in just about everything, probably coating this furniture we're sitting on, the carpets, car seats, adhesives, fast food containers -- all of these things," said Baltimore District Geologist Brian Shedd, principal investigator for the research.
Even though they are common in everyday products, there have been growing concerns in recent years that these chemicals, at high enough concentrations, may have adverse human health effects in people who ingest them through contaminated soil or groundwater.
The research team will be using a scaled aquifer model to learn more about how PFAS behave in soil and groundwater in a setting where chemistry and aquifer conditions can be controlled.
"To my knowledge, right now, no one else is doing this type of physical research on this scale," Shedd said. "There hasn't been as much study of these compounds in the dissolved phase, and how they behave in the environment at relatively low concentrations."
This type of information is important to designing future cleanup methodologies and measuring their effectiveness in addressing PFAS contamination.
The Environmental Protection Agency is currently assessing PFAS as emerging contaminants of concern and developing potential guidelines and maximum allowable concentrations, which would drive cleanup activities should high enough concentrations be found.
While those efforts are going on within the EPA, the Department of Defense is being proactive and working to learn more about these chemicals and the potential for contamination from military activity. For the DoD, PFAS was more commonly used in the past in Aqueous Film Forming foam (AFFF), a firefighting agent used to suppress fuel fires, and training areas where the foams were used repeatedly are a main focus area for assessment and potential remediation. While used since the 1970s, the Army has ceased the use of AFFFs except for emergencies and is collaborating with the Navy and the rest of DoD in its assessments of substitutes.
"A lot of the sites we're working at with these compounds involve fire-fighting foams, which are used for petroleum fires and the like because they're resistant to both oil and water so this stuff just loves to spread, cover up the fire, and extinguish it quickly," Shedd said. "While the compounds are commonly found in all kinds of consumer products, the concentrations tend to be higher in the environment where you have repeated use of the product, like fire training areas where frequent practice with these foams occurred."
According to the EPA, PFAS are very persistent in the environment and in the human body -- meaning they don't break down and they can accumulate over time. This has led to challenges in designing cleanup activities meant to address PFAS contamination.
Shedd and his team said their study should benefit not only the DoD, but also other government agencies and the private sector.
"Our hope is that the results will be extremely valuable to the DoD and others in both evaluating effectiveness of cleanup efforts and designing cleanup efforts as well as for further research regarding these compounds going forward," Shedd said.
The team constructed a scale aquifer in the historic jail building at Baltimore District's Fort McHenry Yard facility near Baltimore District's existing soils laboratory. The aquifer is a tank about six feet by eight feet that is partially filled with soil and has a grid of data collection points installed within; the only indication from the surface of the system as to the complex processes ongoing within. By pumping PFAS contaminated water into the scale aquifer, the team will be able to learn more about how the compounds behave in the environment and how they move, or don't move throughout the aquifer.
"What our study is going to be looking at is what happens when you essentially contaminate an aquifer with this material," Shedd said. "How quickly does it move through the aquifer? How readily does it sorb to the soil? Things like advection, which is the flow of the contaminant; dispersion, which is basically the resistance to flow so it's how the plume spreads out as it flows; and then matrix diffusion which relates to the persistence of contamination from leaching even after a source has been removed."
This effort will require a great deal of data gathering and analysis so the Baltimore District study team has partnered with nearby UMBC, where they are already on the forefront of working with and studying PFAS, to allow students to support the research. Dr. Lee Blaney, associate professor at UMBC and an environmental engineer, said working with PFAS provides his students with a unique learning opportunity.
"The environmental fate and transport of PFAS are quite different than other traditional and emerging contaminants. As such, the students working on this project will be forced to find novel solutions to understanding the fate and occurrence of PFAS during the soil and groundwater experiments performed by the U.S. Army Corps of Engineers," Blaney said. "Students will also benefit from the multi-disciplinary team composed of academics and professionals from the U.S. Army Corps of Engineers and U.S. Geological Survey. The technical knowledge and project management skills that the students learn will help to prepare them for their future jobs."
The USGS and the U.S. Army Corps of Engineers' Engineer Research and Development Center are also major parts of the research team.
"Baltimore District is proud to be on the leading edge of PFAS research," said Baltimore District Engineering Division Chief Ron Maj. "This important research going on at Fort McHenry should benefit not only the Army and the rest of the DoD, but also other governmental and non-governmental entities working to address potential PFAS contamination all over the country and beyond."
The PFAS research effort is expected to be completed in 2019 and the study team will be submitting their findings to academic journals and holding a workshop to disseminate their findings amongst other agencies, and environmental professionals from across the country.