The enactment of the Resource Conservation and Recovery Act (RCRA) in 1976 and the Hazardous and Solid Waste Amendments to RCRA in 1984 created management requirements for hazardous waste facilities. The facilities within the Oak Ridge Reservation (ORR) were in the process of meeting the RCRA requirements when ORR was placed on the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List on November 21, 1989. Under RCRA, the actions typically follow the RCRAFacilityAssessment/RCRAFacilityInvestigation/Corrective Measures Study/Corrective Measures Implementation process. Under CERCLA, the actions follow the Preliminary Assessment/Site Investigation/Remedial Investigation (RI) Feasibility Study (FS)/Remedial Design/Remedial Action process. The development of this document will incorporate requirements under both RCRA and CERCLA into an RI work plan for the first phase of characterization of Bear Creek Valley (BCV) Operable Unit (OU) ,_. To effectively evaluate the cumulative impact of releases from multiple sources of contamination, a structured approach has been adopted for ORR based on studies of the groundwater and surface water separate from studies of the sources. Based on the realization of the complexity of the hydrogeologic regime of the ORR, together with the fact that there are numerous sources contributing to groundwater contamination within a geographical area, it was agreed that more timely investigations, at perhaps less cost, could be achieved by separating the sources of contamination from the groundwater and surface water for investigation and remediation. The result will be more immediate attention [Records of Decision (RODs) for interim measures or removal actions] for the source OUs while longerterm remediation investigations continue for the hydrogeologic regimes, which are labeled as integrator OUs. OUs designated as both source and groundwater OUs are projected to reach a final ROD. Those identified as source OUs only will be addressed initially in interim action RODs. Upon completion of all proposed source OU interim actions, sufficient monitoring data of the integrator OUs will be available to determine if the interim actions have been effective, and, if not, further remediation would be undertaken in the integrator OU final ROD. BCV OU 4 is the groundwater/surface water integrator unit in the valley. This work plan represents the first phase of a two-phase investigation of the integrator unit. Phase I addresses the shallow groundwater and surface water component of BCV OU 4. This phase is designed to investigate migration pathways in the active conduit flow in the aquifer in BCV and the connections between groundwater and surface water, which have been identified as the main data gaps in understanding BCV Hydraulic Regime. Phase II will address the intermediate groundwater and the deeper flow system. Data from the investigations on the dense nonaqueous phase liquid plume and the Maynardville Exit Pathway study will be included in Phase II. The...