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' 3.0 INVESTIGATIVE RESULTS 3.1 Groundwater Monitoring Results The s hallowest groundwater in this portion of the city of Lodi is reported to occur under unconfined ' conditions (Environmental Forensic Investigations, 2002) On September 30, 2004, the highest point measured from the monitoring wells was 6 66 feet (msl)and occurred m monitoring well PT-MW4 The lowest elevation of the groundwater surface measured from the monitoring wells was 6 17 feet (msl)and occurred in monitoring well PT-MW6 A summary hydrograph for monitoring well PT-MWI is presented as Figure 5 The average depth to groundwater surface in the six monitoring wells was approximately 46 5 feet below Iground surface(bgs) The groundwater surface has fallen about 0 5 foot since the last monitoring event (September, 2004) ' Electrical conductivity concentrations in the monitoring well water samples were determined to range from 152 to 265 µmhos/cm This low-conductivity value is typical of reported electrical conductivity values of local groundwaters found near the Mokelumne River(Figure 2) Concentrations of electrical conductivity in waters from the Mokelumne River are reported to range from 200 to 350 µmhos/cm because the relative short distance from the watershed source in the Sierra Nevada and Quaternary alluvial terrain the waters traverse(Page, 1986) Temperature and pH concentrations in the monitoring well waters is typical of 1'groundwater encountered in the Lodi area(Environmental Forensics Inc, 2002) lie 3^2 Groundwater AnabAi al Results No groundwater analytical results are available for this quarterly monitoring period 3.3 Local Groundwater Flow Direction and Gradient The groundwater surface undulates slightly but has a gentle slope toward S50W with a gradient of 0 001 (Figure 4) This flow direction and gradient are consistent with published groundwater data from the City of Lodi(Environmental Forensic Investigations, Inc , 2002)and San Joaquin County Department of Public Works(2004) groundwater surface elevations for the North San Joaquin Water Conservation District 3_4 Petroleum Hydrocarbon Groundwater Plume No information is available for the petroleum hydrocarbon groundwater plume for this monitoring event 4.0 PLANNED FUTURE WORK The next planned operation for this site will include additional Quarterly Status Report(QSR) and quarterly monitoring report(QMR)for the period ending December 31, 2004 A sensitive receptor survey of the nearby water supply wells will be completed during the I'quarter of 2005 MainlDWnvironmeniallParmarTexacoWepons1093004QMR wo 4