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,1 y * CAM B R I A (ppb) benzene in MW-8 during the March sampling event Methyl tertiary butyl ether (MTBE) was detected in well MW-6 at 16 ppb dunng the January sampling event and in well MW-8 at a concentration of 4 0 ppb during the March sampling event It was not detected in the other wells Benzene and MTBE data from these sampling events are presented on Figures 3 through 5 ANTICIPATED SECOND QUARTER 2002 ACTIVITIES Monthly sampling was voluntarily implemented at this site following the September 2001 sampling event and continued through first quarter 2002 The monthly sampling has not yielded significantly different data than the quarterly events, therefore we will revert back to quarterly sampling for this site Blaine will sample the site quarterly and coordinate the event with the former Chevron station located at 301 West Kettleman Lane according to the existing sampling schedule Blaine will gauge and sample all site wells and tabulate the data Cambria will prepare a groundwater monitoring report CONCLUSIONS AND RECOMMENDATIONS . Soil analytical results from investigations including, and subsequent to, the tank removal activities during January 1999 demonstrate that the residual petroleum hydrocarbons and MTBE in soil are limited to the northwestern dispenser area Cambria's May 17, 2002 Site Investigation and Soil Vapor Extraction Test Report, documents that the November 2001 soil vapor extraction (SVE) test was successful in removing a significant amount of this residual source material from the soil beneath the northwestern dispenser Soil analytical data collected from a confirmation borings drilled adjacent to well MW-5, suggest there is little or no remaining source material, and therefore,it is unlikely that any remaining mass would impact groundwater beneath the site There are currently two groundwater monitoring wells onsite (MW-5 and MW-8) and one offsite well in the bicycle lane of West Kettleman Lane (MW-6) No MTBE has been detected in well MW-5, the source area well, since September 2000 (with the exception of a 1 1 ppb detection in November 2001) Note that the November 2001 results for all three wells are not consistent with historical or current concentrations, and are considered anomalous The historical groundwater analytical results from well MW-5 indicate that petroleum hydrocarbons and MTBE detected in soil have not impacted groundwater beneath the site Groundwater samples from well MW-6 have contained the highest detected MTBE concentrations (99 ppb in December 2001) The groundwater flow direction beneath the site has consistently been towards the south to southwest Therefore,MW-6 is the upgradient well, and it 1346 2