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' 3.0 INVESTIGATIVE RESULTS <br />' 3.1 Groundwater Monitoring Results <br /> The shallowest groundwater in this portion of the city of Lodi is reported to occur under unconfined <br />' conditions(Environmental Forensic Investigations, 2002) On December 10, 2004, the highest point <br /> measured from the monitoring wells was 6 66 feet (msl)and occurred in monitoring well PT-MW4 The <br /> lowest elevation of the groundwater surface measured from the monitoring wells was 6 17 feet (msl)and <br />' occurred in monitoring well PT-MW6 A summary hydrograph for monitoring well PT-MW1 is <br /> presented as Figure 5 <br />' The average depth to groundwater surface in the six monitoring wells was approximately 46 5 feet below <br /> ground surface(bgs) The groundwater surface has fallen about 0 5 foot since the last monitoring event <br /> (September, 2004) <br />' Electrical conductivity concentrations in the monitoring well water samples were determined to range from <br /> . 152 to 265 µmhos/cm This low-conductivity value is typical of reported electrical conductivity values of <br /> local groundwaters found near the Mokelumne River(Figure 2) Concentrations of electrical conductivity <br />' <br /> in waters from the Mokelumne River are reported to range from 200 to 350 pmhos/cm because the relative <br /> short distance from the watershed source in the Sierra Nevada and Quaternary alluvial terrain the waters <br /> traverse(Page, 1986) <br />' Temperature and pH concentrations in the monitoring well waters is typical of I'groundwater encountered <br /> in the Lodi area(Environmental Forensics Inc, 2002) <br /> 1 • <br /> 3^2 Groundwater Analtical Results <br /> Groundwater analytical results indicate maximum concentrations of petroleum hydrocarbons and related <br /> gasoline fuel constituents present in the monitoring wells for this quarter monitoring event are as follow <br /> Constituent Concentration Well <br /> • benzene 170 pg/L PT-MWl <br />' toluene 150 Vg/L PT-MW 1 <br /> ethylbenzene 87 pg/L PT-MW 1 <br /> xylene 290 lig/L PT-MW l/3 <br />' TPH Gasoline 6,400 gg/L PT-MW3 <br /> MTBE 19 jig/L PT-MW1 (1 6 pg/L in MW3) <br /> TBA ND <br />' DIPE ND <br /> TAME ND <br /> 1,2-DCA 8 3 µg/L PT-MW3 (6 8 lig/L in MW1) <br />' 1,2-EDB 3 5 pg/L PT-MW3 <br /> • Main\D\Environmental\ParmarTexaco\Rep nslt23104QMR wN 4 <br /> I <br />