Construction began in June on a remediation system for contaminated soils and groundwater located in the central portion of the Lab site.
Some soils and groundwater in Operable Unit IV contain volatile and semi-volatile organic compounds from a 1977 spill. Approximately 25,000 gallons of Number 6 fuel oil and mineral spirits were released through a ruptured line attached to a storage tank located southeast of Brookhaven National Laboratory's Central Steam Facility.
The proposed remediation strategy, agreed upon by the three parties overseeing the Lab's cleanup (U.S. Department of Energy, U.S. Environmental Protection Agency and N.Y.S. Department of Environmental Conservation), was documented back in March of 1996 in the "Operable Unit IV Record of Decision."
The Record of Decision, the first to be reached at BNL, followed an extensive investigation of the area, consideration of several remediation alternatives and a public comment period. The system has been in the design phase for the past year.
Combining technologies
The remediation system combines two technologies to remove contaminants from the soil and groundwater. Air sparging and soil vapor extraction work together, forcing pressurized air into the groundwater to bubble these volatile compounds out of the water and soil and carry them upward. Powerful vacuum pumps recover the resulting vapors and pipe them to a treatment facility.
The combination of the two technologies has been proven to be very effective at other, non-BNL sites, removing as much as 98 percent of the contamination.
The system will include 48 air sparging and 23 soil vapor extraction wells. Construction is expected to be completed by November 1997, and the system is expected to operate for a minimum of two years.
Operable Unit IV also contains radiologically contaminated soils at a sump and a sump outfall area that received wastes from the Reclamation Facility (Building 650). Building 650 formerly served as BNL's decontamination area for clothing and heavy equipment. While the final remediation of these soils will be conducted as part of other activities, monitoring of the area will continue under Operable Unit IV.
For more information, see the Operable Unit IV Remedial Design Specifications and Drawings for the Air Sparge/Soil Vapor Extraction System, which will be available for review in July at the Lab's four information repositories (for locations, see page 11).