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%(1 Mr Kyle Christie Project 0805-142 003 January 24, 1996 Page 2 In June 1995, EMCON observed the installation of two off-site vapor extraction wells (VW-12 and VW-13) (EMCON, report in preparation) Concentrations of total petroleum hydrocarbons 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 oil and grease (TOG) was detected in the sots 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: FOURTH QUARTER 1995 EMCON was contracted by ARCO to monitor the groundwater monitoring wells previously installed at the site Field work included measuring depths to groundwater and collecting groundwater samples for subjective and laboratory analyses EMCON used these data to evaluate the gradient and direction of groundwater flow beneath the site On November 15, 1995, a technician from EMCON measured depths to groundwater 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 wellhead elevations of the monitoring wells at the site were previously surveyed by Tom O Morrow, Inc 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 November 15, 1995, was to the southwest with a hydraulic gradient of 0 002 (see Figure 3) Typically, the flow direction has been toward the south, except for the sampling event conducted during the second quarter 1994, at which time the groundwater flow direction was towards the northeast Groundwater elevation data are presented on Figure 3 and in Table 1 Groundwater elevations increased 0 60 feet in well MW-1 from the previous sampling event (August 1995) and decreased approximately 0 40 foot in wells MW-2 and MW-3. Groundwater samples were analyzed for TPHG and TPHD using Environmental Protection Agency (EPA) Method 5030/Cahforma 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 Dissolved hydrocarbons were not detected in wells MW-2 and MW-3, but were present in well MW-1 TPHG was detected in well MW-1 at a concentration of 320 parts per billion (ppb) TPHG and benzene concentrations are shown on Figure 2 SAO N\PJM80MOS 1420 3DS-95Vas 1