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• (February 2001). The report found that other than acetone and methyl chloride (common laboratory contaminants), VOCs were detected in samples from 8 monitoring wells during 1999 and 2000. VOCs were most commonly detected at trace levels and in samples obtained from wells MW-13, MW-14, and MW-21, in the northeastern corner of the existing Forward Landfill. The most frequently detected VOCs in groundwater include: benzene, cis-l,2-dichloroethene, tetrachloroethene, toluene, 1,1-dichloroethane, and 1,1,1-trichloroethane. The concentrations at which these analytes were detected did not exceed state or federal drinking water standards. Based on a review of the existing data, the GLA report finds that several combined factors indicate that landfill gas production in WMU B is the source for VOCs in the groundwater at the existing Forward Landfill. These factors include: the locus of VOC detections near unlined landfill cell WMU B, the erratic pattern of low VOC detections, the relative long list of VOCs that are detected, the detection of VOCs in both upgradient and downgradient monitoring wells, and the consistency of inorganic water quality in both upgradient and downgradient wells near the site. GLA concluded that the potential impacts associated with the VOCs in the • groundwater appear to be small because the concentrations of VOCs are well below drinking water standards and the absence of VOCs at offsite monitoring locations indicate that VOCs degrade or disperse within a relatively short distance of the landfill boundary. At the existing Austin Road Landfill, a Solid Waste Quality Assessment Test in 1989 found a significant groundwater quality impact. Several VOCs were found in the downgradient monitoring wells. An evaluation monitoring program was implemented in three phases to determine the vertical and horizontal extent of contamination. Phases I and II confirmed VOC impacts along the entire downgradient edge of the landfill and in the first encountered water bearing zone. Phase III indicated the chlorinated hydrocarbon impacted groundwater extends laterally as far as 1,000 feet downgradient of the edge of the landfill. A corrective action program (CAP) was proposed in 1991 to address the chlorinated hydrocarbon impact to groundwater. The plan was approved by the RWQCB in June 1991 and involves the following actions: • Forward Landfill)TD 3-15 L:\Allied\2000.193\Reports\jtd:Sec-3.0:05/21/02 BRYAN A.STIRRAT 6 ASSOCIATES