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19 July 2000 AGE-NC Project No 96-0232 Page 28 of 29 • AGE roughly calculates that the arithmetic average concentration of MTBE in ground water extracted during the quarter(812 3 µg11) multiplied by 141,875 gallons of water extracted (599894 liters)yields 487 grams of MTBE removed from the plume of impacted ground water,dust a bit more than a pound of MTBE in over 1 1 million pounds of water extracted Analytical results from the three monthly monitoring events show that the greatest MTBE concentration on-site is in the First Zone of MW-1 (5,700 ,ug/l), the greatest off site concentrations were detected in First Zone of MW-12, near Three B's domestic well (2,500 kZg/l), the 93 µg/1 maximum concentration previously detected in the intervening MW-7, near Rocky's Restaurant domestic well and other site data suggests that the impact detected in MW-12 may not be directly related to the Flag City Chevron release, future monitoring may provide more insight to the nature of the MW-12 occurrence The most Intense MTBE impact on ground water in the Second Zone was encountered In MW-11, the impact in MW-9 was slightly less, and was minor In MW-6 Other wells completed in this zone were non-detect for MTBE, limiting the plume extent toward MW-8,MW-10, MW-12 and MW-13 Rocky's Upper Zone is monitored only in MW-10 and MW-11, MTBE was detected only in the MW-11 samples MTBE was not detected in any of the monitoring well samples (MW-8 through MW-13), collected from the Secondary Aquifer Zone MTBE was detected xn the Primary Aquifer Zone only in MW-11,near Rocky's Restaurant domestic well The compound was detected at concentrations as high as 10,ug/l in the MWA I samples Data from MW-8, MW-9,MW-10,MW-12 and MW-13 limit the lateral extent of impacted ground water in the Primary Aquifer TPH-d was detected In the )nidal ground water samples collected from the Secondary and Primary Aquifer Zones, but was non-detect in subsequent samples AGE Interprets the results of all work completed over the quarter to show that The release of hydrocarbons and MTBE occurred In the areas of the fuel dispensers, UST pit and/or storm drain, migrated through the First Zone and upper Second Zone to the Rocky's Restaurant domestic well, at which point it apparently migrated vertically to the Rocky's Upper, Secondary Aquifer and Primary Aquifer Zones 13 0 RECOMMENDATIONS Based upon data collected from the site, AGE recommends Advanced GloEm iron mental Inc