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Mr. Cecchuni January 22, 1993 Page 2 IPROCIEIDUES Figure 1 shows the approximate location of the ground water monitoring wells UST-1, SI-1, SI-2, and SI-3. On December 7, 1992, an ESE representative measured the static water level in well UST-1 using an electric water level tape. ]Product as a sheen was observed in the well but was immeasurable. ESE bailed approximately 25 gallons of a water and product mixture from the well and then 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 on January 6, 1993,when ESE measured the depth to ground water from the top of casing at 82 84 feet One sample of ground water from well UST-1 was collected and submitted to ESE Analytical Laboratory of Peoria, Illinois (ESE-Peona), a Califorma-certified analytical laboratory. A ground water sample was analyzed for Total Petroleum Hydrocarbons as gasoline (TPH-G), Total Petroleum Hydrocarbons as diesel, (TPI-D) and Benzene, Toluene, Ethlybenzene, and total Xylenes (BTEX). IFRNDRNGS Table 1 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). 1n the ground water sample collected from well UST-1 in December 1992, analytical results reported concentrations of TPH-G and TIPH-D at 3.4 and 100 parts per million (ppm), respectively. Benzene was reported at a concentration of 5 parts per billion (ppb). Prior to the current ground water monitoring program initiated in August 1992,ESE sampled well UST-1 in September 1990. The increase in petroleum hydrocarbons observed in September 1992 relative to 1990 data may have been due to the influx of surface runoff from the washing of the fuel island area that entered through the broken well box. The current concentrations of TPH-D and Benzene decreased whereas the concentrations of TPl�I-G, ]Ethlybenzene and Xylenes increased slightly relative to September 1992 data. CONCLUSMNS Analyses of the ground water sample collected from well UST-1 in December 1992 showed detectable concentrations of TPH-G, TPH-D, and BTEX. Although a product sheen was observed in December 1992, no free product was observed in well BUST-1 in January 1993. Based on analytical results for the two monitoring events conducted since August 1992, no clear trend in hydrocarbon concentrations were observed. However, the increase in petroleum hydrocarbon concentrations of recent data compared to September 1990 data is significant. Since the former broken well box was repaired in September 1992, current data reflects petroleum hydrocarbon concentrations in ground water.