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' Review of the analytical results of the middle `B" casing groundwater sample group, indicated that the extent of hydrocarbons in groundwater had little variation from the results of the previous sampling event ' in December 2000 Variation to the previous results included results of samples from wells MW-6B and MW-8A The detection of TPHg and benzene in groundwater from well MW-613 dropped from 12,000 ' pg/L to 1,800 gg/L and from 5,600 pg/L to 510 pg/L, respectively The detection of 60 µg/L TPHg and 9 4 gg/L benzene in groundwater from well MW-8A in December 2000 was not detected in March 2001 ' Other than these variations, the extent of hydrocarbons at the groundwater surface was centered at the former dispenser island and included the central portion of the site around the building The eastern and ' western extent of the hydrocarbon plume extends beyond the property boundaries The hydrocarbon concentration map for the middle casing wells is included as Figure 7 Analysis of groundwater samples from the lower casing wells indicated that detectable hydrocarbons were relatively wide spread but concentrated along the western property boundary near well MW-6 The sample from well MW-6 contained the highest concentrations of TPHg (9,900 pg/L) and benzene (3,100 µg/L) of the sample group Results also suggest that the hydrocarbon plume at 60 to 100 feet bgs appeared to be wide spread along the eastern property boundary Samples from wells along the eastern property boundary, monitor wells MW-5 to MW-7, contained detections of hydrocarbons However, results of samples from monitor wells MW-2 and MW-3 suggests a polarization between the east and west portions of the site Analysts of groundwater water from the central portion of the site (monitor wells MW-2 and MW-3) did not contain detectable concentrations of TPHg or benzene and did contain detections of TPHd and other volatile hydrocarbons The northern extent of hydrocarbons in groundwater from the deep casings was defined by the sample from well MW-8, which was the only sample from this sample group that did not contain detections of hydrocarbons The extent of hydrocarbons in groundwater from approximately 60 to 100 feet bgs is undefined to the east and west of the site Laboratory analysis of the lower casing sample group for MTBE, TBA, DIPS, ETBE, TAME indicated a single detection of MTBE Groundwater from monitor well MW-4 contained MTBE at a concentration of 18 pg/L • 07/101O1 Blaes Project#002-70950-02 13 bpm C 1BLAESIU-Hau1170950170950ri01 doc 1