The Air Force Center for Environmental Excellence (AFCEE) is committed to protecting public health. As part of this commitment, we wish to provide you an update on cleanup system construction and current field work activities.

CS-10 and SD-5South EXTRACTION CLEANUP SYSTEMS and CLEANUP INVESTIGATION UPDATE

• A recently mailed neighborhood notice provided information about six new groundwater monitoring wells being installed along Hooppole Road. This work continues the Chemical Spill-10 (CS-10) leading edge investigation conducted on Ashumet Pond during the past year. The data collected from these new monitoring wells will help engineers determine the location of the leading edge of the CS-10 groundwater plume.

Drilling of monitoring wells is scheduled from 7:00 a.m. to 7:00 p.m., Monday through Friday and from 8:00 a.m. to 6:00 p.m. on Saturdays. Operations are expected to be complete in early August. Several drill rigs will be used simultaneously to install the monitoring wells. The construction zone for a drill rig is approximately 20 x 80 feet, so drilling operations will be located partially in the street with one lane closed to traffic. A police detail will be on hand to ensure traffic safety. The wells will be flush to the ground surface when completed and will be opened for inspection and sampling work on an infrequent basis. Paving of Hooppole Road will occur this Fall after well installation is complete.

• The two extraction wells located on Hooppole Road continue to pump 175 gallons per minute of volatile organic compound (VOC) contaminated groundwater, pumping a total of approximately 25.3 million gallons of groundwater through April 2000. This system has removed approximately 10.9 pounds of VOCs, from the groundwater aquifer. Workers will continue to require access to the extraction well vaults on a regular basis to perform routine operation and maintenance work.

The two extraction wells and piping on Hooppole Road is associated with cleaning up portions of the CS-10 groundwater plume [formerly known as the Trichloroethylene (TCE) plume] and remaining portions of the Storm Drain-5 South (SD-5S) groundwater plume. The CS-10/SD-5S extraction wells began operating on January 22, 2000. These two extraction wells are pumping contaminated groundwater through double-walled pipes to the Sandwich Road Treatment Plant located off Sandwich Road in Mashpee. The clean water is returned to the aquifer using re-injection wells located near the Sandwich Road Treatment Plant.

Together, the Wheeler Road and Hillside Avenue systems have treated a total of approximately 46.6 million gallons of groundwater, removing 3.3 pounds of VOCs from the groundwater since the systems began operating. Carbon canisters that remove contaminants from the air stream of the air stripper have been replaced four times at both system locations since they began operating. Changing carbon canisters is a regularly scheduled part of operating and maintaining these cleanup systems in order to ensure their effectiveness.

The continued effectiveness of both recirculating wells with a closed loop configuration has allowed engineers to decide that the systems can remain operating with this modified design. This will allow vent pipes and associated support poles near each recirculating well vault to be removed in mid-July.

Two recirculating wells were installed in spring 1999 and began operating June 17, 1999. One is located under Wheeler Road and a second under the corner of Highland Street and Hillside Avenue. In July 1999, air monitoring of the systems detected three VOCs in the air stream within the vault. No VOCs were detected at the actual discharge point to the atmosphere. The Massachusetts Department of Public Health reviewed the concentrations of contaminants detected within the vaults. They determined that there would be no human health risk associated with exposure to the concentrations of contaminants detected during air monitoring. However, in order to eliminate any potential exposure, both systems were changed to close the air discharge pipe and re-incorporate the treated air back into the air stream of the treatment system. Closing the air discharge pipe on the system prevents any air discharge from the system and prevents any potential exposure to contaminants present within the air stream of the treatment system. Modifications to both systems were completed August 7, 1999.