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• Monitoring well MW-6 had no noticeable odor, floating product or discoloration. • Monitoring well MW-8 had no noticeable odor, floating product or discoloration GROUNDWATER SAMPLE RESULTS Table I summarizes the results of laboratory analyses for groundwater samples obtained during our August 1992 quarterly groundwater sampling Included in Table I are the State of California Maximum Contaminant Levels (MCL's) for the constituents analyzed during our sampling Figure 2 illustrates the locations of the monitoring wells and their corresponding contaminant concentrations. A copy of the laboratory results is included at the end of this letter TABLE I Analytical Laboratory Results Sample TPH Benzene Toluene E.Benzene Xylam Total Lead Mw-1 4720 1.3700 1400 012 MW-8 ND ND ND ND ND ND MCL's NIA 1 1000 680 1750 50 NOTES • TPH Total petroleum hydrocarbons analyzed per method 8015 modified/purge and trap Results are reported in parts per million(ppm) Detection limit = 0 1 ppm for gasoline (g),0 2 ppm for diesel fuel(d)and 0 5 ppm for motor oil (mo) • Benzene,toluene,ethyl benzene,and total xylenes Aromatic volatile organics analyzed per EPA Method 602 Results are reported in parts per billion (ppb) Detection limit = 0 5 ppb • Total lead Analyzed per EPA method 6010 Results are reported in parts per million(ppm) Detection limit = 0 05 ppm • ND Not detected • NIA. Not applicable • MCL. Maximum Contaminant Levels(MCL's)in parts per billion(ppb)per the State or California Regional Water Quality Control Board's A Compilation of Water Quality Goals,September 1991 An MCL for total petroleum hydrocarbons has not been established • MW-2, MW-3,MW-4,MW-5,MW-6 and MW-7 could not be sampled due to the lack of groundwater to the wells DISPOSITION OF PURGED WELL WATER Groundwater purged from the monitoring wells was containerized in a 55-gallon drum and stored on the site Following receipt of the analytical data, Ramos Environmental Services of West Sacramento collected and disposed of the drummed water on 24 September 1992 as a RCRA hazardous waste liquid under Uniform Hazardous Waste Manifest number 92056442 CONCLUSIONS The following conclusions are based on data obtained during the current and past samplings Figure 2 illustrates the locations of the wells and their corresponding contaminant concentrations • The direction of the local groundwater gradient was calculated to be toward the east-northeast during this current sampling This corresponds to the groundwater gradient direction calculated for prior samplings • Monitoring well MW-1, located in the center of the prior tank cluster, had detectable levels of petroleum hydrocarbons, similar to prior samplings ANDERSON CONSULTING GROUP