New system could provide detailed images — even of soft tissue — from a lightweight, portable device.
For the last 10 years, MIT researchers have participated with the US Geological Survey (USGS) in studies to test groundwater at Otis Air Force Base on Cape Cod. Their goal: To identify physical, chemical and microbiological processes which affect the fate and transport of groundwater contaminants, a special concern on the narrow land that is Cape Cod.
In the mid-1970s the state funded a USGS project to investigate the environmental impact of a sewage treatment plant at the air base. The plant puts treated sewage onto filtration beds, a common disposal practice in New England. Denis LeBlanc, the USGS researcher sent out to do the initial testing, remembers how he learned of the problem firsthand: He opened a faucet in his hotel room and the tap water foamed as it came out. It turned out that Falmouth, one of the municipalities abutting the base, had put in a well supplying water to the town in the middle of the plume of contaminants that flowed into the groundwater from the state-approved treatment plant.
At the time, no one knew the contaminants were from the military base. Later groundwater testing revealed volatile organic and other hazardous compounds in eight contaminated plumes at the military base. One plume derives from a fire-training site where an airplane shell was regularly set afire with jet fuels and solvents so that trainees could learn how to put out fires.
Kathryn Hess, a doctoral candidate in the Department of Civil and Environmental Engineering, has been doing research at the site for the past eight years. One of the issues she is looking at is how physical and chemical variability of the aquifer sediment affects transport of contaminants. A significant result of the research is a better understanding of the importance of vertical sampling. When looking for groundwater contamination, the researchers agree, one can sometimes miss the contamination unless the vertical spacing of sampling is small enough. To get around this problem, researchers installed custom-designed multi-level samplers on a regular basis.
A plan is in the works to expand MIT's efforts at the site, allowing students in the new environmental engineering program to participate in hands-on research.
A version of this article appeared in the November 17, 1993 issue of MIT Tech Talk (Volume 38, Number 14).