Fact sheet # 98-25
December 1998

Western Aquafarm Site Update
A fact sheet providing information on the long-term monitoring of one of the cleanup sites at the MMR.

The purpose of this fact sheet is to provide information on the long-term monitoring of one of the cleanup sites at the Massachusetts Military Reservation (MMR). Items in italics are defined at the end of this fact sheet.

Source of the Contamination
The Western Aquafarm site was used for the storage and transfer of aviation gas (AVGAS) and jet fuel (JP-4) in the 1950’s and 1960’s. It is an area of formerly leaking underground storage tanks (UST’s).

Primary Contaminants
The primary contaminants of the Western Aquafarm site are fuel-related compounds, including ethylbenzene and xylenes. The highest levels detected, over the last two years, of ethylbenzene and xylenes are 1,300 and 6,100 parts per billion (ppb), respectively in monitoring well 39MW0002 (see map on Fig. 1). The federal and Massachusetts state safe drinking water standard or maximum contaminant level (MCL) for ethylbenzene is 700 ppb and 10,000 ppb for xylenes. Other compounds detected, at trace levels, are chlorinated solvents, including tetrachloroethene (PCE), and cis-1,2 dichloroethene (cis-1,2 DCE). The highest measured levels of PCE are less than 3 ppb (28MW0018B), and 1 ppb for cis-1,2 DCE (28MW0573). These values are below their respective federal and state MCL’s of 5 and 70 ppb.

Area Affected by the Contamination
Groundwater contamination at and from the Western Aquafarm site is not defined as a plume, since only one well (39MW0002) is above the MCL for ethylbenzene (see Fig.1).

Source Cleanup
As part of the base-wide abandoned aqua-fuel system removal project, the UST’s were removed in 1994 and 1995. An aqua-fuel system uses a water displacement principle-as fuel is being pumped into a tank, the water was then displaced by the fuel and discharged into a one acre drainage basin. The work included pumping and removing the contents of 17 underground fuel tanks, and the associated piping and valves. Concrete pads and structures were also removed. Soil sampling and analyses were conducted to confirm that clean closure was achieved. The removal was completed in March 1995 and resulted in the excavation of approximately 450 cubic yards of soil that was thermally treated at the Fire Training Area 1 (FTA-1) Soil Treatment Facility.

Groundwater Monitoring
After evaluation of all data and analysis, an agreement was reached in 1996 between the Air Force Center for Environmental Excellance (AFCEE), the U.S. Environmental Protection Agency (EPA), and the Massachusetts Department of Environmental Protection (DEP). It concluded that long-term monitoring was an appropriate alternative for groundwater contamination in the vicinity of the Western Aquafarm site. The reasons for the decision include the fact that: [1] there are very low concentrations of contaminants; [2] currently, no one is using the groundwater for drinking water purposes; and [3] the vertical and lateral extent of the low-level contamination is relatively small (limited to one well).

What’s Next
The Western Aquafarm site has been sampled quarterly since a decision was made in the summer of 1996. Four new monitoring wells and two test borings were installed as part of the long-term monitoring program over the past year. These new wells provided valuable data to evaluate the magnitude and migration, if any, of the groundwater contamination.

The results showed that there has been little change in the Western Aquafarm groundwater contamination over the past two years. Therefore, the current long-term monitoring program will continue in the future.

For More Information
Copies of the Final First Annual Comprehensive Eastern Briarwood & Western Aquafarm Groundwater Report are available at the main libraries of Bourne, Falmouth, Mashpee, Sandwich, the USCG (on-base library), and the IRP office. The final Second Annual Comprehensive Eastern Briarwood & Western Aquafarm Groundwater Report is scheduled to be released in February.

Doug Karson, Community Involvement Specialist
HQ AFCEE/MMR
322 East Inner Road
Otis ANGB Base, MA 02542-5028
Phone: (508) 968-4678 x 2 Fax: (508) 968-4673
e-mail: doug.karson@mmr.brooks.af.mil

Jim Murphy, Community Relations Coordinator
USEPA Region I, One Congress St
Suite 1100 (RAA)
Boston, MA 02114-2023
Phone: (617) 918-1028 Fax: (617) 918-1029
e-mail: murphy.jim@epa.gov

Ellie Grillo, Community Involvement Coordinator
MassDEP
20 Riverside Drive
Lakeville, MA 02346
Phone: (508) 946-2866 Fax: (508) 947-6557
e-mail: ellie.grillo@state.ma.us

Glossary
cis-1,2 dichloroethene (cis-1,2 DCE)—a chlorinated solvent, used for industrial purposes. Most commonly associated with the natural biodegradation of TCE, and/or PCE.

ethylbenzene—a chemical component of fuels (gasoline).

maximum contaminant levels (MCLs)—the maximum concentration of a given contaminant allowed in drinking water under state and federal regulations.

tetrachloroethene (PCE)—also referred to as perchloroethene; a man-made solvent commonly used for metal degreasing and in dry-cleaning clothes.

xylenes—a chemical component of fuels (gasoline).