Groundwater Restoration at Lawrence Livermore National Laboratory
Livermore, California
For over 20 years, Weiss Associates has been the principal hydrogeologic contractor supporting the U.S. Department of Energy's environmental restoration at the Lawrence Livermore National Laboratory (LLNL) CERCLA Superfund Site. Localized spills, leaking tanks and impoundments, process cooling water, and landfills released volatile organic compounds (VOCs), fuel hydrocarbons, chromium and tritium to sediments and groundwater, primarily from 14 major source areas. Recently, Weiss Associates' geologists, hydrogeologists and modelers have focused on assisting the Environmental Restoration Department implement source area remediation to expedite groundwater cleanup.
Low-permeability, hydraulically-isolated source area sediments containing elevated concentrations of chlorinated VOCs continue to transfer contaminants to groundwater and prolong site cleanup. Weiss Associates' geologists and hydrogeologists support the Livermore Site ground water restoration by assisting with: 1) characterizing the subsurface at high resolution, 2) cataloging each source area, and 3) identifying innovative technologies appropriate for remediating each source area. Innovative technologies include chemical oxidant flushing, augmented bioremediation, thermal methods, and induced fracturing. Weiss Associates' staff have applied innovative field techniques, including depth-discrete sampling, to collect and compile high quality data in source areas. Sophisticated geospatial modeling software is employed to interpret and illustrate subsurface conditions and contaminant distribution in the source areas.
Because of dynamic vadose zone and aquifer conditions created by the ongoing pump-and-treat remediation, optimizing hydraulic capture and the effectiveness of the containment well field is an ongoing task. Weiss Associates' quantitative hydrogeologists and modelers are assisting LLNL with evaluation of well-field hydraulics/pneumatics and above-ground treatment facility system limitations. Weiss Associates' staff have analyzed contaminant trends and chemical signatures to evaluate plume migration and the impact of source areas on downgradient VOC concentrations. Sophisticated analytical and numerical modeling tools are being used to evaluate the performance and efficiency of the groundwater extraction well fields in meeting the remedial objective. Additionally, Weiss Associates' staff have played a key role in preparing all major CERCLA documents, including the Remedial Investigation, Feasibility Study, Proposed Plan, Record of Decision, Remedial Designs, Compliance Monitoring Plan, and Five-Year Reviews.
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