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• <br /> 29 November 2005 <br /> Flag City Chevron Fact Sheet <br /> Page 3 of 5 <br /> (located approximately 450 feet towards the south)under California Regional Water Quality Control <br /> Board General Order 5-00-119 for discharge to surface waters of ground water from cleanup of <br /> petroleum fuel pollution and under National Pollutant Discharge Elimination System(NPDES)waste <br /> water discharge permit no. CAG915001. From the 27,086,201 gallons of treated ground water, a <br /> grand total of 13.33 pounds of MTBE was estimated to have been removed. <br /> 4.0. ASSESSMENT OF MTBE-IMPACTED SOIL <br /> Laboratory analysis of eighty-two soil samples from the subsurface investigation detected MTBE <br /> in 19 samples;the greatest MTBE-impacted soil was encountered near the south-southwest sections <br /> of the site(UST pit area);however,significant MTBE-impacted soil was also encountered near the <br /> southeast and northeast comers of the fuel dispenser area. The vertical extent of MTBE-impacted <br /> soil has been modeled to extend to maximum depths of 40 feet bsg. The lateral extent of MTBE- <br /> impacted soil at the site has been modeled as an elongated, narrow plume that is limited on-site <br /> towards the north and southwest sections of the site. <br /> When the soil data collected at the site is plotted in both plan view and cross sectional views, the <br /> apparent volume of MTBE impacted soil totals approximately 4,433 cubic yards, which yielded a <br /> total of approximately 1.54 pounds of MTBE,or an estimated 0.25 gallons of MTBE remaining in <br /> soil at the site. <br /> 5.0. ASSESSMENT OF MTBE-IMPACTED GROUND WATER <br /> The Flag City Chevron unauthorized release of MTBE occurred in the areas of the UST pit and the <br /> fuel dispensers; the most intense on-site MTBE concentrations were historically detected adjacent <br /> the southwest comer of the UST area. The Flag City Chevron dissolved MTBE plume has been <br /> modeled to have migrated approximately 180 feet westward through First Zone and Second Zone <br /> ground water,to the area of the former Rocky's Restaurant domestic water well,at which the plume <br /> appeared to converge with that of the Three B's Truck Plaza (14749 N. Thornton Road) MTBE <br /> ground water plume. <br /> A third MTBE ground water plume has been modeled as originating at least 300 feet to the north at <br /> New West Petroleum(6437 West Banner Avenue)and was drawn through First Zone and Second <br /> Zone ground water to the Flag City Chevron UST and fuel dispenser areas by the previous pump- <br /> and-treat ground water extraction activities. <br /> When the ground water data collected at the site is plotted in both plan view and cross sectional <br /> views, the apparent volume of MTBE-impacted ground water remaining at the site totals <br /> approximately 1,082,009 gallons,which yielded a total of approximately 1.75 pounds of MTBE,or <br />