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Groundwater samples were collected from the five monitor wells on November 19, 1992 and submitted for laboratory analysis The analytical results indicated that no detectable concentrations of TPH were present in the groundwater samples collected from the five monitor wells at the site Concentrations of benzene were detected in groundwater samples collected from monitor wells MW2, MW3 and MW4 at 0.58 micrograms per liter (µg11), 7 7 µg11 and 18 µg11, respectively Toluene and ethylbenzene were detected only in the groundwater sample collected from well MW4 at a concentration of 1 2 µg/1, respectively Xylenes were detected in groundwater samples collected from MW3 and MW4 at concentrations of 1 2 µg11 and 13 5 µg/l, respectively Groundwater samples were collected from the five monitor wells on June 4, 1993 and submitted for laboratory analysis The analytical results indicated that detectable concentrations of TPH as gasoline were present in the groundwater samples collected from monitor well MW 1 and MW4 at concentrations of 0 69 µg11 and 0 84 µg11, respectively Concentrations of benzene were detected in groundwater samples collected from monitor wells MW2, MW3 and MW4 at concentrations of 9 5 µg/l, 78 µg/l and 430 µg/l, respectively. Toluene and ethylbenzene were detected in the groundwater sample collected from MW 1 at 6 0 µg11 and 1 1 µg/l, respectively, and ethylbenzene was detected in groundwater samples from MW2 and MW4 at concentrations of 0 92 µg11 and 20 14g11, respectively Xylenes were detected in groundwater samples collected from MW 1, MW2 and MW4 at concentrations of 1.1 µg11, 6 9 µg1l and 91 ug/l, respectively Groundwater samples collected from the five monitor wells on September 3, 1993 were submitted for analysis Concentrations of TPH as gasoline were detected only in the groundwater sample collected from MW-4 at 1 1 µg11 Concentrations of benzene were detected in groundwater samples collected from monitor wells MW-2, MW-3 and MW-4 at concentrations of 7 1 µg/l, 11 µg11 and 120 µg11, respectively This report presents the results of the December 1993 quarterly groundwater monitoring event conducted at the Site, the fourth groundwater sampling event performed at the Site This work was conducted in accordance with the State Water Resources Control Board Leaking Underground Fuel Tank (LUFT) and Regional Water Quality Control Board (RWQCB) guidelines for the preliminary evaluation and investigation of underground tank sites Groundwater samples were not collected following the November 1992 sampling event until June ' 1993 Quarterly sampling has continued at three month intervals (i e , September, December) since June 1993 2.0 WATER LEVEL MEASUREMENTS tWater surface elevation data were obtained from the monitoring wells at the Site on December 3, 1993 Water surface elevation data are presented in Table 1. Contours of equal water surface elevation developed from the data are presented in the Potentiometnc Surface Map included as Figure 2 Sample event data sheets are included as Appendix I 22zo!¢a6 3