Volume 6, No. 2

Promoting Cooperation to Maintain and Enhance
Environmental Quality in the Gulf of Maine

By Maureen Kelly

A U.S. Geological Survey (USGS) research site on Cape Cod will close in September if Congress approves the proposed cut of the agency's $13.9 million Toxics Substances Hydrology Program from the federal budget in fiscal year 2003.

Since 1983, the USGS has studied an underground sewage plume emanating from the 22,000-acre Massachusetts Military Reservation (MMR) in an effort to understand the processes that affect the behavior of contaminants in groundwater. Sewage is the most common threat to ground water purity in the United States. What scientists learn from the Cape Cod site can be applied to remediation at other contaminated aquifers nationwide.

In the late 1970s, the USGS discovered what is now called the Ashumet Valley Plume; the first of 15 contaminant plumes found originating beneath the base. Over nearly a century, hazardous waste from landfills, military material, fuel, solvents and treated sewage leached into the ground beneath the reservation, which sits above an aquifer that is the sole source of drinking water for 200,000 year-round and 520,000 Cape Cod summer residents. The Air Force and National Guard are now overseeing a massive clean-up, under the U.S. Environmental Protection Agency's toxic waste clean-up program, Superfund, and the Safe Drinking Water Act that is expected to cost over $1 billion by the time it is finished.

As the sewage plume, which is over two miles long, filters through the Cape's sandy soil towards Buzzards Bay, it provides a field laboratory to USGS scientists and their academic colleagues who conduct long-term research to find how toxins spread and degrade underground. The USGS sunk over 10,000 sampling devices into the ground to monitor variations in contaminant concentrations along the plume's path and used tracer experiments to track the movement of toxins.

"The geochemical environment in aquifers that have been contaminated by organic chemicals and nutrients is very complex," said Denis LeBlanc, a USGS hydrologist. "More field research is needed to help understand how physical, chemical and biological processes work together in affecting the fates of various types of contaminants."

The soil at the study site is "alive with bacteria," he said, and there is much more to be learned about the role microbes play in breaking down and diluting toxins.

Contaminants continue to seep beyond the MMR's boundaries. This spring, the town of Bourne shut down several public wells after trace levels of perchlorate, a chemical used as a propellant in munitions, was detected in the water supply.

Web site for the Toxics Substances Hydrology Program:
http://toxics.usgs.gov/investigations/