Brookhaven National Laboratory's Environmental Restoration Division (ERD) has received a $1.5 million grant from the U.S. Department of Energy (DOE) to help finance the construction of an innovative groundwater treatment system.
The "Technology Deployment Initiative" program was established in 1997 by DOE's Environmental Management division to promote the use of new and innovative technologies in site cleanups across the United States. Last November, ERD submitted a proposal to use the funding to construct a cutting-edge groundwater treatment system.
The system, which would be located in the industrial park just south of the Lab and the Long Island Expressway, would address portions of a chemical groundwater plume extending beyond the Lab's southern boundary. In December, ERD learned the proposal had been approved, and a portion of the grant money has already been made available.
In-Well Air Stripping
This innovative technology employs in-well air stripping, which works by mixing air with contaminated groundwater. The mixing process "strips" or removes volatile organic compounds (i.e., solvents like carbon tetrachloride) from the water. The clean water exits the well and recirculates (see diagram), and the air carries the volatile organic compounds, now in gaseous form, upward within the well to the surface. The air is then vented from the well and sent through a carbon filter to remove the contaminants. The clean air is then forced back into the well under pressure and the cycle repeats. This closed-loop system prevents any air emissions, and the contaminated water is treated within the well without ever reaching the surface.
In-well air stripping was shown to be effective in removing contamination during a 1996 pilot study at the Lab. Similar systems have proven successful at several sites across the country, including the Savannah River Site in South Carolina, the Edwards Air Force Base in California, and the Massachusetts Military Reservation.
Off-site plume is focus
The portion of the groundwater plume that is the focus of this cleanup action extends from the central, developed portion of Brookhaven National Laboratory (BNL) into an industrial park just south of the Lab's southern boundary. The off-site portion of this plume is comprised primarily of carbon tetrachloride, a solvent once widely used at the Lab and in industry for degreasing equipment. The solvent, which was once commonly used as a dry cleaning chemical, has been detected in on- and off-site monitoring wells at depths of 180-300 feet below land surface. Concentrations as high as 5,100 parts per billion (ppb) have been detected. The U.S. Environmental Protection Agency and New York State drinking water standard for carbon tetrachloride is 5 ppb. A pump-and-treat system, constructed in 1997, is currently cleaning up the on-site portion of the plume and preventing further off-site migration.
Hookups offered
Although a 1995 residential well sampling program in this area showed no contamination from BNL above drinking water standards, DOE has offered area home and business owners free connections to the public water supply as a precautionary measure.
Construction of the $3 million groundwater treatment system is expected to begin this summer. Currently, six wells are planned, each capable of treating 100 gallons of water per minute. Additional in-well air stripping systems are being considered for other areas of groundwater contamination at the Laboratory.
For more information, see the Operable Unit III Pre-Design Report, expected
to be available for review in April 1998 at the Lab's four information repositories
(for locations, see page 7).