(Initial distribution: May 1997)
What is the Action Memorandum?
The memorandum documents the decision by the U.S. Department of Energy to conduct a removal action to address groundwater contamination within an area known as Operable Unit III at Brookhaven National Laboratory.
The action addresses elevated levels of tritium found in groundwater south of BNL's High Flux Beam Reactor. This "short term" removal action is being undertaken to prevent further southward migration of tritium in groundwater at levels above the drinking water standard.
What is the action?
Groundwater extraction wells have been installed along Princeton Avenue at the leading edge of the plume (see illustration), where tritium concentrations are presently at or below the drinking water standard of 20,000 picocuries per liter. The objective is to capture this groundwater at the leading edge of the plume and pump it back to the center of the site to provide additional decay and dispersion before reaching the site boundary. This water will then be discharged into an existing recharge basin. The pumping system began operation on May 12, 1997.
This action will prevent the leading edge of the tritium contamination from migrating any further south by constantly returning it to the center of the site.The tritium in this water will decay and disperse to below detection levels after it re-enters the groundwater and begins migrating south. Further, any tritiated groundwater currently further south than the Princeton Avenue extraction wells is already below drinking water standards and will eventually be intercepted by a second Operable Unit III pump-and-treat system, due to be operational in June 1997.
Volatile organic compounds that are caught up in the water with the tritium will be treated with an activated carbon filter before the water is recharged.
The system will be sampled regularly in accordance with state permit requirements. All monitoring is overseen by the Department of Energy, the U.S. Environmental Protection Agency and N.Y. State Department of Environmental Conservation.
Why this alternative?
This action is being performed as a short term removal action to prevent the plume of tritiated water from continuing to move toward the site boundary. While stopping the spread of contamination, it will give BNL and the Department of Energy more time to finalize a long-term plan to address the highest levels of contamination located immediately to the south of the High Flux Beam Reactor.
The chosen removal action was approved by the three regulatory agencies overseeing the Lab's operation: the Department of Energy, the Environmental Protection Agency and the Department of Environmental Conservation. The Suffolk County Department of Health Services has no objection to this action being taken.
The pump-and-recharge option was chosen because it had:
Options under evaluation for long-term remediation include:
These technologies, except for the first option, were considered infeasible for the removal action due to time constraints and their unproven applicability to environmental tritium remediation. Pumping and recirculating to the source area was not selected as the removal action because of its potential for impacting on-site supply wells, mobilizing the high tritium concentrations near the High Flux Beam Reactor, and creating a potential exposure pathway in the developed and populated central area of the Lab site.
Natural attenuation through dispersion and decay is also a long-term remediation option under consideration.
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