From the outset, the Department of Energy (DOE) and the Brookhaven National Laboratory (BNL) considered the protection of human health to be the most important goal of the cleanup program. Because exposure to groundwater contamination had the greatest potential to impact human health, the focus was to ensure that local drinking water supplies were clean and safe. Early efforts concentrated on determining the locations of the contamination, installing treatment systems to clean up the groundwater, and remediating sources of contamination like landfills and underground tanks. DOE and the Lab are committed to protecting Long Island’s sole-source aquifer, a vital natural resource.
Chemical Groundwater Contamination
The most common chemical pollutants found in the groundwater are called volatile organic compounds (VOCs). These compounds were, and still are, used in a wide variety of consumer products and industrial processes. At BNL, one common VOC called carbon tetrachloride, for example, was found in pesticides, in cleaning fluids and degreasing agents, in fire extinguishers, and in spot removers; use of VOCs at the Lab dates back to the 1940s. The environmental impact of these materials was not well understood during the early years of their use, and what were considered acceptable disposal methods for these chemicals at that time are no longer utilized. In some instances, these chemicals were spilled onto the ground or poured into drains.
These releases to the environment allowed the VOCs to eventually make their way into the groundwater. Once the Lab discovered that these compounds had entered the groundwater and were moving off the site, more than 3,000 temporary and permanent on- and off- site groundwater monitoring wells were installed between 1990 and 2005 to develop a detailed picture of the nature and extent of contamination.
In 1996, shortly after off-site groundwater contamination was discovered, DOE funded the connection of more than 1,500 homes south and east of BNL to public water supplies as a precautionary measure. While the Lab was working to determine the extent of the off-site contamination through its extensive groundwater testing program, the Suffolk County Department of Health Services tested 800 private wells in the area. They found no contamination attributable to BNL in these private wells. However, seven residences were immediately provided with bottled water or connected to public water because contaminants above drinking water standards were found in their wells – the contamination was eventually traced back to an industrial park area north of their neighborhood and immediately south of BNL.
Volatile organic compound contamination from the Lab was found in the aquifer off-site, but at depths much deeper than the reach of typical homeowner wells. Once the extent of the contamination was determined, the Lab, DOE, the Environmental Protection Agency (EPA) and the New York State Department of Environmental Conservation (NYSDEC) decided it was necessary to address impacts to the sole source aquifer through a comprehensive on- and off- site groundwater cleanup program. The objective of this cleanup program was to minimize or prevent further migration of contaminants in the aquifer and to reduce contaminant levels to meet drinking water standards.
Between 1996 and 2005, a total of 16 groundwater treatment systems were constructed to treat VOC contamination in the aquifer. Seven treatment systems were constructed on-site, with three of these positioned along the Lab’s southern boundary to prevent additional contaminants from moving off of the site, and six other systems were built south of the Lab to address VOCs that had moved off-site.
By 2008, the systems had cleaned more than 12.8 billion gallons of water and removed approximately 5,900 pounds of VOCs from the aquifer. The cleanup program’s effectiveness can be seen by the shrinking of key areas of groundwater containing contaminants at levels above drinking water standards.
The community south of BNL played a significant role in determining the locations of the two treatment systems that were constructed in their neighborhood. Many community members were unhappy with some of the locations originally proposed for the treatment systems. During a series of community meetings they asked why one of the treatment buildings needed to be located in the residential neighborhood, so close to homes, and why another had to be placed on the same side of a street where children often played.
They proposed solutions – in the first case, that the water be piped 3,000 feet south to Brookhaven-Calabro Airport, where a treatment building was already being constructed. In the second case, they suggested that the location for the treatment building be moved across the street, so the children could continue to play safely.
The Lab and DOE staff listened and found they could accommodate the community’s wishes and save money in the long term. The first solution, which involved installing piping beneath neighborhood roads, was also a concern to some residents. To alleviate these concerns, the Lab included a detailed road paving specification for installation that exceeded Town of Brookhaven requirements. The project was completed to the satisfaction of the community, the Lab, DOE, and the regulatory agencies.
Radiological Groundwater Contamination
In 1997, radioactive tritium was detected in groundwater monitoring wells south of BNL’s High Flux Beam Reactor (HFBR), near the center of the Lab site. An investigation determined that the spent fuel pool in the basement of the reactor building had been leaking for at least a decade, resulting in a narrow “plume,” or area of contaminated groundwater above the drinking water standard, stretching approximately 2,200 feet south from the reactor. The outcry from many Long Islanders, including elected officials, eventually resulted in the firing of Associated Universities, Inc. (the company that had managed BNL for 50 years). In 1998, Brookhaven Science Associates, a nonprofit company founded by Stony Brook University and Battelle Memorial Institute, was hired by DOE to manage and operate the Lab. Two years after the discovery of the tritium, in 1999, the reactor was permanently shut down.
Initially, the spent fuel pool was drained, and a groundwater pumping system was set up at the southern edge of the plume to ensure that the plume would not reach the site boundary. This system was operated for several years, and then placed on standby until 2007, when it was reactivated to control the southernmost area of the plume. Additional contaminated groundwater close to the reactor building was extracted to remove the highest tritium concentrations from the groundwater. The strategy was effective, and the plume is currently less than a third of its former size.
In the late 1990s, several areas of tritium-contaminated groundwater near two of the Lab’s accelerator facilities were also discovered. The sources of the contamination were immediately identified as areas with soil shielding that had been made radioactive, or “activated,” by the accelerator. These areas were immediately capped to prevent rainwater infiltration and the release of additional tritium from the soil. Groundwater monitoring has demonstrated that the source controls have been effective and that the tritium in the groundwater is naturally degrading as expected.
Other areas of groundwater containing radioactive strontium-90 were also identified on-site, and two treatment systems have been installed to clean up the aquifer. To date, 35 million gallons of groundwater have been treated and 16.7 milli-curies of strontium-90 have been removed.