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I/ Z Mr Kyle Christie Project 0$05-142 003 • November 21, 1995 Page 2 as gasoline (TPHG), total petroleum hydrocarbons as diesel (TPHD), and benzene, toluene, ethylbenzene and total xylenes (BTEX) were below laboratory detection limits in soil samples collected from the wells Total and grease (TOG) was detected in the soil sample collected from well VW-12 at a depth of 315 feet below ground surface at a concentration of 96 parts per million GROUNDWATER MONITORING: THIRD QUARTER 1995 EMCON was contracted by ARCO to monitor the groundwater monitoring wells previously installed at the site Field work included measuring depths to water and collecting groundwater samples for subjective and laboratory analyses EMCON used these data to evaluate the gradient and drrectlon of groundwater flow beneath the site On August 11, 1995, a technician from EMCON measured depths to water and collected groundwater samples from wells MW-1 through MW-3 for subjective and laboratory analyses Floating product or product sheen was not noted in samples from the wells (see Table 1) Sampling and analysis procedures are presented in Appendix A The well head elevations of the monitoring wells at the site were previously surveyed by Tom O Morrow The surveyed elevations and the depth to groundwater measurements (summarized in Table 1) were used to evaluate the potentiometnc surface beneath the site The groundwater flow direction on August 11, 1995, was to the southwest with a hydraulic gradient of 0 02 (see Figure 3) Groundwater elevation data are presented on Figure 3 and in Table 1 Groundwater elevations decreased approximately 2 17 feet from the previous sampling event(May 1995) Groundwater samples were analyzed for TPHG and TPHD using Environmental Protection Agency (EPA) Method 5030/Cahforrua DHS LUFT and EPA Method 3510/ California DHS LUFT, respectively, TOG using EPA Method 5520 B and F, and BTEX using EPA Methods 5030/8020 These samples were analyzed at Columbia Analytical Services, Inc , In San Jose, California. The results of these analyses are summarized in Table 1 Copies of the chain-of custody records and laboratory analysis reports are presented in Appendix B TPHG concentrations were detected in all wells, concentrations ranged from 55 parts per billion (ppb) in well MW-3 to 240 ppb in well MW-1 Concentrations of benzene were not detected at laboratory detection limits in all wells TOG was not detected in groundwater samples collected from all wells. TPHD was detected in well MW-1 at a concentration of 108 ppb The sample contained components that eluted in the diesel range, but the chromatogram did not match the typical diesel fingerprint (see Appendix B). TPHD was not detected at laboratory detection limits in the other wells TPHG and benzene concentrations i' are shown on Figure 2. SAO N\PJ0005\08051420 3CS-9Spw 1