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CPT Investigation Work Plan <br /> BP Oil Site No 11193 <br /> C A IVI B R i A Stockton, California <br /> August 12, 1999 <br /> Hydrocarbon and MTBE Distribution Analysis of soil samples collected during well installation <br /> and equipment upgrade activities indicate that the highest concentrations of hydrocarbons and MTBE <br /> are located beneath the tanks,piping and dispensers(see Appendix A) Gasoline range organic(ORO) <br /> concentrations of more than 1,000 milligram per kilogram(mg/kg)were reported in samples collected <br /> from beneath three of the four dispensers, and MTBE concentrations of more than 10 mg/kg were <br /> reported in samples collected at 15 feet bgs within the tank excavation <br /> The maximum concentration of MTBE reported for groundwater samples collected from the <br /> monitoring wells on January 19, 1999 was 3,600 micrograms per liter (µg/1) in well MW-2, which is <br /> located north of the tanks (see Figure 2 and Appendix A) As shown on the graph below,the water <br /> table elevation has increased while GRO concentrations exhibit a decreasing trend and MTBE <br /> concentrations exhibit an increasing trend A water sample collected from the tank excavation on <br /> December 17, 1998 contained 120,000 µg/l of MTBE and 210µg11 of t-amyl methyl ether(TAME) <br /> No ethanol, t-butanol (TBA), di-isopropyl ether(DIPE) or ethyl t-butyl ether(ETBE) were detected <br /> in the analyzed samples <br /> Well MW-2 <br /> 35,000 -5 <br /> 30,000 <br /> 25,000 -10 a ca <br /> e <br /> 20,000 W E <br /> 15,000 Y o — <br /> c 10,000 -L - -- <br /> -20 3 75 <br /> v 5,000 <br /> -25 <br /> rn rn rn rn11 rn LO (0 rn rnI,- M <br /> Date <br /> �GRO MTBE - Water Elevation <br /> �Expon (GRO) =Expon (MTBE) <br /> 3 <br />