Recirculating Well Technologies at the Massachusetts Military Reservation, CS-10 Plume

Site Name:

Massachusetts Military Reservation


Cape Cod, Massachusetts

Period of

Pilot testing - December 21, 1996 - May 1997
Continued operation of pilot systems through May 4, 1999


Field demonstration

UVB recirculating wells (with air stripping)
- UVB uses an in-well stripping platform, operated under negative pressure, with a four-screen design
- Two UVB wells were used; pumps operated at 39 to 61 gpm; the air stripping unit used an air to water ratio ranging from 120:1 to 150:1
- Air treatment consisted of GAC

NoVOCs recirculating wells (with air stripping)
- NoVOCs uses a double-cased, in-well vapor-stripping system; pressurized air-lift pumping is used to extract water through screens located at the base of the plume; VOCs are stripped and filtered through GAC; treated water is reinjected
- Two NoVOCs wells were used; pumps operated at 160 gpm for one well and 140 gpm for the other
- 24 monitoring wells (8 clusters of 3 each) were used to monitor the groundwater at each test site

Cleanup Authority:
Federal Facilities Agreement 1991

Jim Snyder
322 E. Inner Road, Box 41
Otis ANGB, MA 02542-5028
Phone: (508) 968-4670

Spence Smith
322 E. Inner Road, Box 41
Otis ANGB, MA 02542-5028
Phone: (508) 968-4670, Ext 5603
EPA Contact:
Michael Jasinski
U.S. EPA Region 1
One Congress Street
Suite 1100
Boston, MA 02114
Phone: (617) 918-1352

Chlorinated Solvents
- TCE - 3,200 ug/L, PCE - 500 ug/L, and 1,2-DCE - 58 ug/L

Waste Source:
Fuel spills and leaks from engine maintenance operations and underground storage tanks

Type/Quantity of Media Treated:
- Plume extended approximately 12,500 feet downgradient from the source area, with a width of up to 3,600 feet
- Three hydrostratigraphic zones were identified beneath the test sites - upper, middle, and lower
- UVB pilot test treated 23 million gallons; quantity treated not specified for NoVOCs pilot test

Purpose/Significance of Application:
Field demonstration of two recirculating well technologies to treat chlorinated solvents in groundwater

Regulatory Requirements/Cleanup Goals:
- The pilot tests were conducted to assess the overall feasibility of using recirculating well technology to achieve "significant contaminant reduction" (not further quantified)
- A performance standard was established as 1 ug/L for TCE in the discharge from the air stripper, with TCE used as a measure of total VOCs in the water

- The cumulative mass of TCE removed by the UVB wells during the pilot test was about 18 kg; TCE concentrations in the groundwater were reduced in the upper and lower hydrostratigraphic zones, and remained relatively stable in the middle zone
- The cumulative mass of TCE removed by the NoVOCs wells during the pilot test was about 43 kg; TCE concentrations in the groundwater remained stable
- The pilot study and continued operation indicated that recirculating well technology reduced concentrations of TCE, PCE, and 1,2-DCE; however, a comparison of the two technologies in terms of contaminant reduction could not be made from the available data for several reasons

Cost Factors:
- The actual cost for the CS-10 recirculating well pilot test and subsequent operational period was approximately $3,000,000, consisting primarily of costs for drilling ($1,583,000) sampling ($635,000), and construction ($554,000).
- Information was not provided about the projected cost for a full-scale treatment system.

MMR is a military training facility located in the upper western portion of Cape Cod, Massachusetts, about 60 miles southeast of Boston. Leaks and spills from historical operations including vehicle maintenance and repair, parts cleaning, and painting; storage of petroleum products and hazardous materials; and disposal of wastes in landfills resulted in soil and groundwater contamination. A Technical Review and Evaluation Team recommended that pilot-scale testing of recirculating well technology be performed in the southeastern area of the CS-10 plume within the industrial area to evaluate the effectiveness of this innovative technology for reducing concentrations of contaminants in the groundwater. The pilot testing was performed prior to installation of a groundwater extraction system, identified as the interim remedy for CS-10 groundwater the ROD signed in September 1995.

During the pilot test, the cumulative mass of TCE removed by the UVB wells was about 18 kg and about 43 kg for the NoVOCs system. According to the prime contractor at the site, the results of the pilot tests indicate that recirculating well system hydraulics are more sensitive to site-specific hydrogeologic conditions than extraction, treatment, and reinjection. In addition, modeling results indicated that the presence of low hydraulic conductivity layers can inhibit the establishment of effective recirculation wells.