The primary sources of the CS-10 groundwater plume are the 38-acre area of the former Boeing Michigan Aeronautical Research Center (BOMARC) Missile Site and Unit Training Equipment Site (UTES) located near the eastern boundary of the MMR. The BOMARC Missile Site was operated between 1962 and 1973, and UTES has operated since 1978 to maintain and store armored and other wheeled vehicles. Spills and releases of chemicals occurred in these areas in the past. A preliminary pollution prevention program has been in place at UTES since December 1995 to ensure that petroleum use and disposal do not affect the groundwater.

For the BOMARC site, the remedial investigation, which defines the nature and extent of contamination, has been completed. A feasibility study, which outlines alternatives for treating the contamination, also has been completed. A proposed plan, which describes AFCEE’s preferred alternative for addressing the site, will be released for public comment in early fall 1998. Following public comment, a record of decision describing the final decision will be released; it is scheduled for late 1998. Once the record of decision has been signed, design and construction of the selected remedy will begin.

Primary Contaminants

The primary contaminants of the CS-10 plume are TCE, PCE, and 1,2 dichloroethylene (1,2-DCE). TCE has been detected in the western portion of the plume as high as 400 ppb, and in the southeastern portion of the plume as high as 2,800 ppb, although there have been isolated detections of higher concentrations. EDB has been detected sporadically at low levels. The safe drinking water standard, or maximum contaminant level, is 5 ppb for TCE, PCE, and 1,2-DCE. PCE and TCE are common solvents used for equipment maintenance and degreasing. EDB was added to leaded gasoline, including aviation gasoline (AVGAS), to inhibit the build-up of lead in engines.

Affected Area

Most of the CS-10 plume affects the south-central area of the base. The plume is about 17,000 feet long, a maximum of 4,000 feet wide, and up to 140 feet thick. In general, the plume is more than 120 feet below ground and 60 feet below the water table along most of its length.

The eastern lobe of the plume has migrated off-base in the groundwater near the Falmouth Gate. It has been tracked to the edge of Ashumet Pond. Additional drilling and sampling is scheduled to begin in October 1998 to determine whether the plume is flowing deep under Ashumet Pond. None of the primary contaminants in the plume have been detected in the surface water of Ashumet Pond.

Plume Cleanup

Two pilot tests of recirculating wells began in the eastern lobe of the CS-10 plume near the boundary of the base in December 1996 and are scheduled to run until 1999.

The CS-10 plume was one of four plumes to go through the "decision criteria" process in 1997, a public process that enabled the remedial project managers and the public to compare and evaluate cleanup alternatives.

In August 1997, after careful consideration of the advantages and disadvantages of each plume response alternative and comments received during the public comment period, the remedial project managers from AFCEE, EPA, and MassDEP decided on an alternative to treat the CS-10 plume. The selected alternative uses ETR technology. An extraction fence will be constructed along Sandwich Road; it is expected to be activated in May 1999, at which time the recirculation well pilot systems will be shut off. Active remedial systems will be evaluated for their effectiveness within the body of the plume. An ETR fence is under consideration along the southern portion of the plume; however, results of the Southwest Operable Unit (SWOU) study must be considered before design of the system begins.

Next Steps

• Monitoring wells were installed during the spring, 1998. Ongoing ecological sampling is being conducted. A total of 34 wells were sampled for data gap analysis to prepare the engineering design.
• Engineering design of the selected alternative is underway and will continue throughout 1998. The plans will be available to the public.
• Information updates will be provided to the public periodically.
• AFCEE representatives will meet with neighborhood and other community groups at any time, as requested.
• Extensive coordination among AFCEE, EPA, DEP, and citizen advisory teams will continue.
• AFCEE, EPA, and MassDEP encourage residents to attend citizen advisory team and public meetings, become more informed and involved with the cleanup, and sign up for the site mailing list to receive updates.
• The public will be notified before phased construction of system elements begins.
• System startup will be phased with construction to meet enforceable milestones.
• The enforceable milestone for full-scale system startup is May 31, 1999, for the Sandwich Road fence, and June 28, 1999 for the selected in-plume system.

Boeing Michigan Aeronautical Research Center(BOMARC) Missile Site and Unit Training Equipment Site (UTES)