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1 <br /> Page 3 <br /> Ms Margaret Lagono <br />' June 24, 1996 <br />' MONITORING ACTIVITIES <br /> This quarterly groundwater monitoring and sampling event was conducted May 13 <br />' through May 15, 1996 The depth to groundwater and the presence or absence of PSH <br /> was evaluated in each monitoring well Groundwater elevation measurements for this <br /> quarter are presented in Table 1 Historical groundwater elevation measurements are in <br /> 1 Table 2 <br /> Groundwater samples were collected and analyzed in accordance with United States <br /> Environmental Protection Agency(USEPA) guidelines for TVH-G, and benzene, toluene, <br /> ethylbenzene, and total xylenes using USEPA Methods Modified 8015 and 602, <br /> respectively Western Environmental Science& Technology, located in Davis, California, <br /> performed the analysis Analytical results for this quarter are presented in Table 3 <br /> Historical analytical results are in Table 4 <br /> Groundwater sampling procedures are presented in Appendix A Water sample field data <br /> sheets are presented in Appendix B <br /> QUARTERLY MONITORING RESULTS <br /> The groundwater elevations in the facility monitoring wells on May 13, 1996, ranged from <br /> -29 49 to -28 68 feet MSL (see Table 1) A groundwater elevation contour map is <br /> presented in Figure 3 As shown on the contour map, the approximate groundwater flow <br /> direction is to the east, with an approximate hydraulic gradient of 0 0028 ft/ft <br /> Groundwater elevation data are presented in Table 2 <br /> There was no PSH detected in any of the monitoring wells Hydrocarbon-impacted <br /> groundwater was not detected in wells MW-2, MW-3, MW-6 and MW-11 Detectable <br />' groundwater sample TVH-G concentrations (Figure 4) ranged from 53 to 27,000 µg/L <br /> Detectable groundwater sample benzene concentrations (Figure 5) ranged from 1 2 to 960 <br /> µg/l_ The highest TVH-G and benzene concentrations were measured in the groundwater <br /> sample collected from monitoring well MW-1 However, TVH-G and benzene <br /> 1 concentration trends in samples collected from monitoring well MW-1 appear to be <br /> generally decreasing with time Similarly, hydrocarbon concentrations also appear to be <br /> decreasing in samples collected from monitoring wells MW-4 and MW-10 Certified <br /> analytical results and the chain-of-custody documentation are presented in Appendix C <br /> 1 <br /> E\CTI I0212QTR96 DOC <br /> 1 <br />