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AZURE ENVIRONMENTAL Water table elevation data collected at the Site indicate the general direction of ground-water flow is toward the north, with local variations of flow direction in the area adjacent to the former tank locations at the Site (Figure 3) These data are generally consistent with potentiometric data and interpretations of ground-water flow direction at the Site presented in previous investigation ' reports Shallow ground water in the site vicinity flows toward the north under a hydraulic gradient of approximately 0 002 ft/ft ' 3_2 Ground-Water Sampling and Laboratory Analysis On February 5, 1998, ground-water samples were collected from two downgradient monitoring ' wells (MW-9 and MW-10) The samples were analyzed for total petroleum hydrocarbons as r gasoline (TPHg) and benzene,'toluene, ethylbenzene, and xylenes(BTEX) compounds In ' addition, the samples were analyzed for oxygenates, including methyl tertiary-butyl ether (MTBE) using EPA Method 8260. Historical laboratory analysis results are summarized in Table 3, laboratory certificates are included in Appendix A and field sampling data sheets are ' included in Appendix B Most recent benzene monitoring data are illustrated in Figure 4 Monitoring data collected for wells MW-9 and MW-10 in February 1998 indicate petroleum ' hydrocarbons, including benzene (<0 5 ppb) and MTBE (<5 ppb), were not detected Historical data indicate benzene has not been detected at concentrations greater than 0 5 ppb in downgradient wells MW-9 since January 1995 (0 6 ppb) and MW-10 since October 1994 (0 6 ppb) These data continue to indicate the petroleum hydrocarbon plume has stabilized and is restricted to shallow ground water in the area adjacent to the former tank locations at the Site ' 4.0 TECHNICAL STATUS REPORT ' Work Completed During the First Quarter 1998 Work completed during the first quarter included performance of the quarterly ground-water monitoring program Work Expected to be Completed During the Second Quarter 1998 ' Work expected to be completed during the second quarter includes continued performance of the quarterly ground-water monitoring program 1 Pursuant to the CRWQCB-Central Valley Region's requirements presented in their July 18, 1997 , letter, ground-water samples collected during the fourth quarter 1997 and first quarter 1998 were ' analyzed for oxygenate compounds using EPA Method 8260 Results indicate oxygenate compounds were not detected (see Laboratory Certificates in Appendix A) Additionally, historical results of MTBE analyses using EPA Method 8020 indicate MTBE has never been ' detected in ground-water samples from the Site(Table 3) Based on monitoring results indicating oxygenate compounds do not appear to be present in ground water, sample analysis using EPA Method 8260 will be discontinued 1 ' 2 `