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' TASK 1 - REMEDIAL INVESTIGATION/FEASIBILITY STUDY AT THE B834 COMPLEX Purpose and Rationale The purpose of this task is to complete the remedial investigation/feasibility study of the B834 Complex by January 1989. LLNL has periodically conducted investigations ' of volatile organic compounds (VOC) in soil, rocks, and ground water at the B834 Complex since 1982. These studies identified high concentrations (locally more than 100,000 parts per billion (ppb)) of TCE in a shallow, perched water-bearing zone beneath and southwest of the B834 Complex. It has been determined that prior to 1984, leaks of ' TCE used as a heat transfer fluid at B834 were the source of TCE found in the subsurface. In early 1984 LLNL removed TCE-bearing topsoil from the area of the B834 complex. The soil was treated by aeration, put back in place, and covered with ' polyvinylchloride to minimize surface water infiltration. By January 1989, LLNL plans to: ' 1. Complete the installation of a ground water monitoring system at the B834 Complex (July 1988). 2. Determine the vertical and horizontal extent of the TCE plume beneath the site (July 1988). 3. Complete engineering field studies and pilot extraction tests for remediation ' of the low permeability, partly saturated soils that contain most of the contaminant plume (October 1988). ' 4. Receive approval of a Remedial Alternatives Report to be submitted to the CRWQCB by October 1988. Procedure To complete the remedial investigation/feasibility study of the B834 Complex, LLNL intends to install at least two additional monitoring wells to define the limits of ' the TCE plume south and southwest of B834. The wells will be completed in the upper- most, perched water-bearing zone by the installation of 4.5 inch inside diameter (I.D.) Schedule 40 PVC well casing and screen. The wells will be developed and dedicated pumps installed in accordance with the water yield of the wells. Water samples from the ' monitoring wells in the B834 area will be collected quarterly and will be analyzed by Environmental Protection Agency (EPA) Method 601. ' Engineering field studies and pilot extraction tests will be conducted to evaluate remedial action alternatives. These studies and tests will culminate in a Remedial Alternatives Report to be submitted in October 1988. Analytical data from these new ' wells and the existing monitoring network will be used to estimate the vertical and horizontal extent of the TCE plume. TASK 2 - REMEDIAL ACTION AT THE B834 COMPLEX Remedial action is scheduled to begin in January 1989. A work plan will be submitted prior to initiation of that work. 1 ' -5-