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iff.F-4 -�""N '--I February it, 1992 Quik Stop Markets, Inc. Pnge 5 Project No. 3-49132-32 -. groundwater elevations of 12.04 feet to 12.2dropped bd.lowtween 0.14 foot to Omean sea level ase ed foot on available survey data. The groundwater surfaceppm 0 since the previous sampling. Groundwater contours for July show a predominant easterly flow direction at an apparent gradient of 0.0027. The July 1991 analytical results revealed that no TPHG or BTEX constituents were detected in the water samples collected from the monitoring wells designed T PHG monand it r the lower aquifer (MW-1R, MW-2, MW-3, and MW-4). However, BTEX constituents have increased in the water sample collected from hese analytical the on ell designed to monitor the upper or perched aquifer (MW-5). results appear to indicate that two separate aquifers are present bP:ieath the eastern part of this site. The increases observed in petroleum hydrocarbon concentrations in the groundwater samples from MW-5 observed after the August 30, 1991 pumping of the well may be attributed to the excavation of contaminated soil discussed in the background section of this report. This excavation was located to the west of t%,a dispensing pumps, ites upgradient of monitoring well MW-5. Such soil has been re c conducted to depths observenears the where excavation of cantaminat� lrores aces may be groundwater. Contaminants prev.ousl, contained r isolated p p Y released as the excavation process disturbs the soil. Groundwater depth fluctuations or rainwater percolation could transport the contaminants into the ground with•a grtadualfer e contaminated soil is removed such increases may be temporary, reduction in contaminant levels with time. At this site, a general downward trend can be seen since the July 31, 1991 sampling and analysis. The State of California Department of Health Services (DHS) maintains drinking water standards (maximum contaminant levels [MCL] and action levels CAL)) for petroleum hydrocarbon compounds in drinkir.6 water. The following is a list of the current DH-5 drinking water standards for BTEX: Cr m otivnd Concentrations Benz.:ae 1.0 ppb MCL Toluene 100 ppb AL Ethyl Benzene 680 ppb MCL Total Xylenes 1,750 ppb MCL Groundwater samples collected from the monitoring wells t this site do not exceed the current DHS drinking water standards for these po At the time of the initial groundwater sampling at the site, the SJCPHS required that all - groundwater samples be analyzed for fecal coliform. In our April 8, 1991 sampling