Description of Groundwater Projects

During initial environmental studies, the Brookhaven National Laboratory (BNL) site was subdivided geographically into seven Operable Units (OU). The main Operable Unit dealing with groundwater contamination is OU III. OU I, IV, V, and VI also address groundwater contamination.

Operable Unit I includes groundwater contamination in the southeastern area of the Laboratory that is being addressed by a removal action.

Operable Unit III was developed to address groundwater "plumes," or areas of contamination, emanating from the central and southern portion of the BNL site. The main contaminants of concern are volatile organic compounds (VOCs), strontium-90, and tritium. VOCs have been found both on and off Laboratory property, while strontium-90 and tritium contaminants are confined to the Laboratory site.

Operable Unit IV included groundwater contamination at BNL's Central Steam Facility.  Regulatory agencies have approved the decommissioning of one of BNL's earliest groundwater treatment systems.

The five-year review of the Operable Unit IV treatment system is now available.

Operable Unit V includes groundwater in the eastern-central area of the Laboratory.

Operable Unit VI includes groundwater in an area about 1,000 feet west of Weeks Avenue at depths of 90 - 130 feet below ground. Groundwater in this area contains the chemical EDB (ethylene dibromide), once commonly used as a pesticide and gasoline additive.

Operable Unit III

Volatile organic compounds

A large area of groundwater in the central and southern portion of BNL is contaminated with VOCs. Some VOC contamination extends off site, south of BNL into the East Yaphank area. The off-site contamination is generally below the depths of most private wells. Nevertheless, as a precautionary measure, the U.S. Department of Energy paid for approximately 1,500 homes in the area to be hooked up to public water.

Five treatment systems are already in place and operational to treat this VOC contamination, including two systems at the southern site boundary and one system off site in an industrial park just south of the Long Island Expressway. A new on-site treatment system is scheduled to begin operating this spring. An additional seven treatment systems are planned to be installed and operational by 2006 or earlier.

Strontium-90

There are concentrated areas of strontium-90 contamination in the groundwater at three on-site locations: the Chemical Holes area in the southeast, the Waste Concentration Facility, and the Brookhaven Graphite Research Reactor. The latter two are in the central, developed portion of the site.

This groundwater will be extracted and treated using "ion exchange" to remove the strontium-90. The clean groundwater will be returned to the aquifer. Residual waste containing strontium-90 will be disposed of at a licensed off-site facility.

Tritium

Tritium from the spent fuel pool of Brookhaven's High Flux Beam Reactor has leaked into groundwater in the central portion of the BNL site. The spent fuel pool has been emptied and the High Flux Beam Reactor permanently shut down, removing the source of the tritium.

A pump-and-recharge system was installed in 1997 to remove groundwater containing tritium from the aquifer and pump it to a recharge basin further north. There, the water was allowed to re-enter the aquifer. Groundwater monitoring shows that this system was effective in halting the southward migration of the tritium plume. Tritium levels at this location have been undetectable for over two years, therefore the system has been placed on standby. It can be restarted if monitoring indicates a need.

In addition, low-flow pumping has been conducted to extract the highest levels of tritium from the area south of the reactor. In 2000 and early 2001, a total of approximately 90,000 gallons of water were removed from the aquifer and disposed of off site. Further actions to address the on-site tritium plume are currently under discussion.

Operable Unit VI (EDB)

Historically, the Laboratory has found levels of EDB in OU VI groundwater (in the Manorville area) as high as 6.0 parts per billion (ppb), compared to the drinking water standard of 0.05 ppb. Recent measurements show levels up to 3.6 ppb. Although no residential wells in Manorville contain EDB from the Lab, the U.S. Department of Energy (DOE) offered public water hookups to residents in this area in 1996. Most hookups were completed in 1997. A groundwater treatment system is being installed in this area to remove the EDB from the aquifer. Treatment by carbon filters will be used to reach cleanup goals and to continue to assure that public health is protected.