Remedial investigation work plan for the Upper East Fork Poplar Creek characterization area, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

The Oak Ridge Y-12 Plant, located within the Oak Ridge Reservation (ORR), is owned by the US Department of Energy (DOE) and managed by Lockheed Martin Energy Systems, Inc. The entire ORR was placed on the National Priorities List (NPL) of CERCLA sites in November 1989. Following CERCLA guidelines, sites under investigation require a remedial investigation (RI) to define the nature and extent of contamination, evaluate the risks to public health and the environment, and determine the goals for a feasibility study (FS) of potential remedial actions. The need to complete RIs in a timely manner resulted in the establishment of the Upper East Fork Poplar Creek (UEFPC) Characterization Area (CA) and the Bear Creek CA. The CA approach considers the entire watershed and examines all appropriate media within it. The UEFPC CA, which includes the main Y-12 Plant area, is an operationally and hydrogeologically complex area that contains numerous contaminants and containment sources, as well as ongoing industrial and defense-related activities. The UEFPC CA also is the suspected point of origin for off-site groundwater and surface-water contamination. The UEFPC CA RI also will address a carbon-tetrachloride/chloroform-dominated groundwater plume that extends east of the DOE property line into Union Valley, which appears to be connected with springs in the valley. In addition, surface water in UEFPC to the Lower East Fork Poplar Creek CA boundary will be addressed. Through investigation of the entire watershed as one ``site,`` data gaps and contaminated areas will be identified and prioritized more efficiently than through separate investigations of many discrete units