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Page 3 Ms Margaret Lagono March 20, 1996 ' MONITORING ACTIVITIES This quarterly groundwater monitoring and sampling event was conducted on February 12 and 13, 1996 The depth to groundwater and the presence or absence of PSH was evaluated in each monitoring well Groundwater elevation measurements for this quarter ' are presented in Table 1 Historical groundwater elevation measurements are in Table 2 Groundwater samples were collected and analyzed in accordance with United States Environmental Protection Agency (USEPA) guidelines for TVH-G, and benzene, toluene, ' ethylbenzene, and total xylenes using USEPA Methods Modified 8015 and 602, respectively Western Environmental Science & Technology, located in Davis, California, performed the analysis Analytical results for this quarter are presented in Table 3 ' Historical analytical results are in Table 4 Groundwater sampling procedures are presented in Appendix A Water sample field data sheets are presented in Appendix B QUARTERLY MONITORING RESULTS Theg roundwater elevations in the facility monitoring wells on February 12 and 13, 1996, ranged from -31 51 to -30 37 feet MSL (see Table 1) A groundwater elevation contour map is presented in Figure 3 As shown on the contour map, the approximate groundwater flow direction is to the east, with an approximate hydraulic gradient of 0 0035 ft/ft Groundwater elevation data are presented in Table 2 ' There was no PSH detected in any of the monitoring wells Hydrocarbon-Impacted groundwater was not detected In wells MW-2, MW-3, MW-6 and MW-8 through MW-11 Groundwater samples from monitoring wells MW-2 and MW-10 had previously contained hydrocarbon concentrations Detectable groundwater sample TVH-G concentrations (Figure 4) ranged from 310 to 26,000 pg/1- Detectable groundwater sample benzene concentrations (Figure 5) ranged from 3 1 to 2,400 pg/L The highest ' TVH-G and benzene concentrations were measured in the groundwater sample collected from monitoring well MW-1 However, TVH-G concentration trends in samples collected from monitoring well MW-1 appear to be generally decreasing with time Similarly, ' hydrocarbon concentrations also appear to be decreasing In samples collected from monitoring wells MW-4 and MW-13 Certified analytical results and the chain-of-custody documentation are presented In Appendix C 81CTIIMI QTR96 AOC