(Original distribution: March 1, 1999)
What is the OU III Remedial Investigation Report?
The OU III Remedial Investigation Report describes what contaminants have been identified in Operable Unit III (OU III) and where they are located. The report also contains a Risk Assessment which examines the human health and ecological risks associated with these contaminants.
The OU III Remedial Investigation Report focuses on several areas, or plumes, of groundwater contamination at Brookhaven National Laboratory (BNL). Soils, sediment and surface water were also examined.
What are the findings of the investigation?
The main focus of Operable Unit III is groundwater contamination. The primary groundwater contaminants are solvents (volatile organic compounds, or VOCs), strontium-90 and tritium. The most common VOC contaminants are carbon tetrachloride, tetrachloroethene (also called perchloroethene, or PCE) and trichloroethane (TCA). Other VOC contaminants were also found in lesser amounts.
Soil contamination on site from underground storage tanks at Building 830 is being addressed by a removal action. Other soil samples have shown heavy metals, but at levels that are considered low.
Where is the groundwater contamination?
Three VOC plumes have been identified that extend beyond the southern boundary of BNL. Although the groundwater contaminants are found to be deeper than most residential wells, as a precautionary measure, residents immediately south of BNL were offered public water hookups.
There are three locations on the BNL site where strontium-90 was found at levels above drinking water standards. Strontium-90 has been found at the Waste Concentration Facility, the Brookhaven Graphite Research Reactor and Pile Fan Sump, and in the Chemical Holes area.
A tritium plume was detected on site in December of 1996, through groundwater samples taken near the High Flux Beam Reactor (HFBR). The source was identified as the reactor's spent fuel pool. Tritium at levels above the drinking water standard (20,000 pCi/l) extends approximately 2,600 feet south of the reactor, and is about one mile north of BNL's southern boundary.
What has already been done?
To prevent higher levels of solvents from moving off site, two treatment systems have been constructed. In 1996 and 1997, eight pumping wells were installed at the southern boundary of BNL to remove and treat water contaminated with VOCs. In November 1998, construction began on seven additional treatment wells in an industrial park located south of BNL. This system will also remove solvents from the groundwater.
The tritium plume source has been addressed by emptying the spent fuel pool and installing a system on site south of the leading edge of the plume. In this system, the tritiated water is pumped to the center of the site and released into a basin to re-enter the aquifer. This pump-and-recharge system dilutes the tritium and increases the distance traveled by the water. The resulting increase in the travel time allows natural decay to reduce the level of tritium.
One source of strontium-90 contamination has been addressed by the excavation of the Chemical Holes area and the removal of contaminated soils. Materials which were removed will be sent to a licensed waste management facility for disposal.
What are the risks?
Risk assessments evaluate current and future risks from the contamination, assuming that no cleanup takes place. Human health risks and ecological risks were evaluated in this report. Ecological risks were found to be minimal for the OU III contaminants.
Human health risks were evaluated for both current and future land-use scenarios. Various exposure pathways were considered.
For current land uses, the on-site chemical health risk is minimal. However, the presence of TCA and carbon tetrachloride in the off-site groundwater could potentially pose a health risk to off-site residents if their wells tap the contaminated water and that is their sole water source.
Assuming exposure to the highest detected levels of chemicals, the presence of solvents in the on-site groundwater poses potential health risks to future on-site residents if they use a contaminated well as their sole water supply. For the radiological risk assessment, computer modeling was used to estimate radiation doses and health risks. It was found that if no remedial actions are taken the presence of tritium and strontium-90 in the groundwater could pose a potential carcinogenic risk to a future on-site resident who uses contaminated well water.
What is the next step?
The Feasibility Study has evaluated cleanup alternatives for groundwater contamination. The Proposed Plan has been prepared and proposes cleanup alternatives. Information sessions and a public meeting will be held to discuss the proposed cleanup options. There will be a public comment period from March 1 to March 31, 1999 for the Proposed Plan. After all comments have been reviewed and considered, a final remediation decision will be made jointly by the New York State Department of Environmental Conservation, the U.S. Environmental Protection Agency, and the DOE. The decision will be documented in the Record of Decision for Operable Unit III.
For more information, contact:
U.S. Department of Energy
U.S. Environmental Protection Agency
N.Y. State Department of Environmental Conservation
Copies of the Feasibility Study and the Proposed Plan are available for review at:
Longwood Public Library
BNL Research Library
U.S. EPA, Region II Library
This figure shows the locations of the Operable Unit III groundwater contaminants, and VOC treatment systems. The Chemical Holes are a source of both VOCs and strontium-90.