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AZURE ENVIRONMENTAL September 1998 The ground-water level at MW-2 decreased approximately 3 3 feet during the quarterly period from May 1998 to September 1998 Water table elevation data collected at the Site indicate the general direction of ground-water flow is toward the northeast, 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 potentiometnc 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 northeast under a hydraulic gradient of approximately 0 003 ft/ft 3.2 Ground-Water Sampling and Laboratory Analysis ' On September 9, 1998, ground-water samples were collected from two downgradient monitoring wells at the Site (MW-9 and MW-10) The samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, and xylene (BTEX), and ' methyl tertiary-butyl ether(MTBE) compounds 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 ground-water monitoring data of benzene ' concentrations in ground water are illustrated in Figure 4 The downgradient extent of petroleum hydrocarbons in ground water is monitored at wells MW-9 and MW-10 Monitoring data collected for wells MW-9 and MW-10 in September 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 well MW-9 since January 1995 (0 6 ppb) and well MW-10 since October 1994 (0 6 ppb) Ground-water monitoring data continue to indicate the petroleum hydrocarbon plume is generally stable and is restricted to shallow ground water in the area adjacent to the former UST locations Iat the Site 4.0 TECHNICAL STATUS REPORT ' Work Completed During the Third Quarter-1998 ' Work completed during the third quarter included performance of the quarterly ground-water monitoring program ' On September 10, 1998, Azure submitted to the SJCEHD a proposal for work activities to close a hydraulically actuated bulk truck emptying platform contained in a concrete-lined bunker ('platform bunker") at the Site An approval was received from the SJCEHD on September 11, 1998 Azure submitted a request for a special discharge permit to the City of Stockton Department of Municipal Utilities on October 1 The platform bunker closure activities will be scheduled and performed after receipt of the discharge permit from the City of Stockton ' 2