Brookhaven National Laboratory's fourth cleanup system is now operational. The system is removing contamination from soils and groundwater in the central portion of the Lab's 5,300-acre site.
The cleanup system, which began operating in November, combines two innovative technologies, known as air sparging and soil vapor extraction, to remove chemical compounds from the soil and groundwater.
Forty-eight air sparging wells (pipes that reach 80 feet below the ground) force pressurized air into the groundwater. The resulting air bubbles trap the compounds and carry them upward. Then 23 soil vapor extraction wells (pipes that reach 30 feet below ground and are connected to powerful vacuum blowers) recover the resulting vapors and pipe them to a treatment facility. Carbon filters remove the contamination from the air before it is released.
The source of the contamination was a 1977 spill of approximately 25,000 gallons of fuel oil and mineral spirits. The contaminants were released when a line attached to a storage tank at the Lab's central steam plant ruptured. Soil in the area was excavated, but residual contamination remained.
The remaining soil and groundwater contamination includes breakdown products from the fuel oil and a common solvent, tetrachloroethene. The contamination is confined to the Laboratory site, and no public, private or Lab drinking water supply wells have been impacted by it.
The technologies for this treatment system were selected through a comprehensive evaluation of alternatives that were presented during a December 1995 public meeting. The system is expected to operate for at least two years. Three additional groundwater treatment systems are operating in other areas of the Lab.
For more information, see the Operable Unit IV Remedial Design Specifications
and Drawings report (indexed as a post-ROD document in the Administrative
Record), available for review at the Lab's four information repositories
(for locations, see page 7).