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® Mr. Cecchinru October 20, 1992 Page 2 PROCEDURES Figure 1 shows the approximate location of the ground water monitoring wells UST-1, SI-1, SI-2, and SI-3. On August 5, 1992 an ESE representative measured the static water levels in wells UST-1, SI-1, SI-2, and SI-3 using an electric water level tape. Because ESE discovered that the monitoring well box at the fueling island was damaged,well UST-1 was not sampled in August 1992. Approximately 0.04 feet of product found in well UST-1 in August 1992 probably entered the well through the damaged well box from surface runoff of the fueling island area. On September 18, 1992, ESE replaced the well box and purged and sampled well UST-1 according to the attached ESE Standard Operation Procedure (SOP) No. 3 (Attachment A). No free phase product was observed in well UST-1 in September 1992. One sample of ground water from well UST-1 was collected and submitted to Carus & Tompkins, Ltd., a California-certified analytical laboratory. A ground water sample was analyzed for Total Petroleum hydrocarbons as gasoline (TPH-g), Total Petroleum Hydrocarbons as diesel, (TPH-d) and Benzene, 'Toluene, Et lybenzene, and total Xylenes (BTEX). KNIDIINGS Both current and historical static ground water levels measured in wells UST-1, SI-1, SI-2, and SI-3 are presented in Table 1. The ground water elevation in well UST-1 was 63.73 feet below an arbitrary datum. The water levels have dropped several feet since monitoring began. Figure 1 presents contoured ground water elevations for each well as presented in Table 1 and reveals a ground water gradient of approximately 36 feet per mile (0.007 ft/ft) in a general west direction, which is generally consistent with data collected in 1991 and 1990. Table 2 summarizes analytical data for ground water samples collected from well UST-1. Laboratory reports and chain of custody documents for current data are attached (Attachment B). In the ground water sample collected from well UST-1 in September 1992, analytical results reported concentrations of TPH-g and TPH-d at 1-5 and 350 parts per million (ppm), respectively. Benzene was reported at a concentration of 17 parts per billion (ppb). During previous investigations by ESE,well UST-1 was sampled in September 1990. The current concentrations of petroleum hydrocarbons reported for the ground water sample from well UST-1,which are greater than 1990 data, are probably due to the influx of surface runoff from the washing of the fuel island area that entered through the broken well box. a