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• 07 December 2001 AGE Project No 96-0232 Page 2 of 9 system, an estimated rune pounds of MTBE has been extracted from ground water to date (Table 2) 3.0. ASSESSMENT OF OFF-SITE MTBE-IMPACTED GROUND WATER Off-site, the greatest concentrations of MTBE has been detected in Rocky's Upper Zone water near the Rocky's Restaurant domestic water well in MW-11B at concentrations as high as 310,ug/1, In First Zone water from Flag City Chevron monitoring well MW-7 at concentrations as high as 110 ,ug/l, and in First Zone water from Three B's Truck Plaza monitoring well MW-4 at concentrations as high as 110,ug/l Analytical results of Flag City Chevron and Three B's Truck Plaza monitoring wells are summarized in Tables 3 and 4 Figure 3 depicts the estimated extent of dissolved MTBE in plan view, Figure 4 depicts the approximate extent of MTBE-impacted ground water beneath the site in cross sectional view GC' These figures show Flag City Chevron wells MW-1, MW-7, MW-9A, MW-11A, MW-13A and Three B's Truck Plaza wells MW-1, MW-4 and MW-6 to be located within dissolved MTBE plumes • Off-site toward the west, the dissolved MTBE plume may extend to as much as 75 feet bsg approaching the area of MW-11 B, near the Rocky's Restaurant domestic well (RDW-1) where the underlying fine-grained sedimentary units may thin and pinch out Further westward from RDW-1, the plume ofwater impacted by MTBE appears to extend beyond Three B's Truck Plaza well MW-4, with a potential vertical extent from 15 feet bsg to 75 feet bsg The full westward extent of the Flag City Chevron plume is unknown at this time Contaminants in First Zone ground water at MW-12 and MW-13 include total petroleum hydrocarbons quantified as gasoline (TPH-g), diesel (TPH-d) and motor oil(TPH-mo),benzene,toluene,xylene,MTBE and 1,2-dichloroetliane(1,2-DCA),which suggest that most of the contaminants are from a source other than the Flag City plume It is not known if the suspected plumes are co-mingled in the area between Three B's Truck Plaza wells MW-1, MW-6 and Flag City Chevron well MW-13 and the impacted ground water encountered in Flag City Chevron wells MW-7, MW-11, and MW-13, AGE has modeled them as separate plumes (Figures 3 and 4) 4.0. PROPOSED OFF-SITE REMEDIATION In accordance with a RWQCB's directive to address off-site MTBE-impacted ground water in the RDW-1 area (Appendix A), AGE proposes installation of three 6-inch diameter ground water extraction wells on the Rocky's Restaurant property(14659 North Thornton Road, Lodi, California) for extraction and treatment of impacted ground water AGE proposes to utilize the Flag City . Chevron GAC-and Sunsolve- treatment system for treatment of off-site extracted water by installing Advanced CeoEnvironmental,Inc