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i Quik Stop Market No, 120 January 17, 1991 Project No. 3-49120-31 Page 3 Well TPHD TPHG Benzene Toluene Ethyl Benzene Xylenes MW-1 <50 <50 <0.5 <0.5 <0.5 <0.5 MW-2 <50 55 4.1 10 2.2 11 MW-3 52 110 3.2 8.6 3.8 11 Results in parts per billion(µg/l) <30 Not detected at or above the listed practical quantitation limit for the method. Discussion Groundwater at the site was measured in December 1990 at depths ranging from 45.03 to 46.00 feet below the existing ground surface. These depths correspond to elevations of 33.75 to 33.98 feet below mean sea level based upon available survey data. The apparent groundwater surface dropped an average of approximately one foot since the previous rs show a gently inclined gradient with a predominant flow sampling. Groundwater contou direction to the southwest. The December 1990 analytical results revealed that detectable petroleum hydrocarbon concentrations have increased in monitoring wells MW-2 and MNV-3 since the previous sampling. The State of California Department of Health Services (DNS) maintains drinking water standards (maximum contaminant levels [MCL] and action levels [rte.]) for petroleum hydrocarbon compounds in drinking water. The following is a list of the current DHS drinking water standards for BTEX: Compound =Co.jeentrations Benzene 1.0 ppb MCL Toluene 100 ppb AL Ethyl benzene 630 ppb MCL Total Xylenes 1,750 ppb MCL Groundwater samples from monitoring wells MW-2 and MW-3 contained benzene at -- concentrations that exceed the current DHS drinking water standard. The next quarterly groundwater sampling will be conducted in March 1991.