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FORTH QUARTER 1996 QUARTERLY MONITORING REPORT USA STATION ##65 - LODI NOVEMBER, 1996 The direction of groundwater flow has been calculated to be trending to the southeast with average hydraulic gradient of approximately 0 0033-ft/ft across the site Histonc field data suggests that groundwater generally flows to the south with minor fluctuations to the east and/or 1 west, as shown on Figures 3 through 7 5.2 Results of Groundwater Laboratory Analyses The October 10 1996 , analytical results detected TPH G in three of the sampled monitoring wells (MW-8, S-1, and S-2) Concentrations of TPH G for the October 10, 1996 sampling event ranged from 260 micrograms per liter(µg/1) in MW-8 to 7,100 99/1 in S-1 TPH G was non- detect at the method detection limit (ND) in wells MW-1 through MW-7 Benzene was detected ' in three of the monitoring wells (MW-8, S-1 and S-2) Benzene concentrations ranged from 3 3 µg/l m MW-8 to 1,500 pg/l m S-1 Benzene was ND in wells MW-1 through MW-7 MTBE was reported at levels of 19, 22 and 46 µg11 in MW-8, S-1 and S-2, respectively Analytical ' results are summarized in Table 3, and shown on Figure 8 Copies of laboratory reports and COC documentation are included in Appendix B TPH G and BTEX were non-detect in MW-3 The third quarter sample results for MW-3 indicted TPH G and benzene at 7,000 and 35 µg/1 Histoncal analytical results for MW-3 have been ND to very low petroleum hydrocarbon values, for verifiable results repeatability is necessary to evaluate the southern extent of impacted groundwater The groundwater depths at MW-3 during the third quarter may have exposed or resolubize a localized pocket of petroleum hydrocarbons Downgradient wells continue to be non-detect for TPH constituents o strtuents There does not appear to be any indication of plume nvgration At this time Park recommends the monitoring be continued 5