i BACKGROUND INFORMATION Groundwater quality monitoring activities at the waste-management sites in the Bear Creek Regime have been in progress since the late 1970s and have evolved in response to regulatory changes and monitoring results. A brief description of the waste-management facilities in the Bear Creek Regime, including waste inventories and disposal histories, and a discussion of the regulatory status and groundwater monitoring history of each site, are provided in the following

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... ns. CERCLA Operable Units In 1984, the U.S. Environmental Protection Agency (EPA) and the TDEC determined that several of the waste-management sites at the Y-12 Plant were hazardous waste treatment, storage, and disposal (TSD) units subject to regulation under RCRA (Table 1 ). Three of the TSD units are located in the Bear Creek Regime: the S-3 Site, the Oil Landfarm waste-management area (WMA), and the Bear Creek Burial Grounds WMA (Figure 3 ). These sites were granted RCRA interim status until operating or post-closure RCRA permits were obtained by the DOE. The RCRA post-closure permit applications (PCPAs) for these sites were initially submitted to the TDEC in 1987. Also in 1987, Spoil Area I, the Rust Spoil Area, and the SY-200 Yard were identified as solid waste management units (SWMUs) subject to regulation under section 3004(u) of RCRA (Welch g t a. 1987).