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i 19 July 2000 AGE-NC Project No 96-0232 Page 27 of 29 hydrologic units are roughly defined as the intervals from 5 to 30 feet bsg (First Zone), 40 to 60 feet bsg(Second Zone), 65 to 75 feet bsg (Rocky's Upper Zone), 90 to 105 feet bsg (Secondary Aquifer Zone),and 130 to 150 feet bsg(Primary Aquifer Zone) Specified zones are defined on bases of CPT soil charactenstics data Due to AGE's limited data from the First Zone, Second Zone, and Rocky's Upper Zone, the possibility that the upper three zones may not be hydraulically distinct is not dismissed The data collected strongly suggests to AGE that the Secondary Aquifer Zone and the Primary Aquifer Zone are separate hydrologic units, although the fine grained unit between Rocky's Upper Zone and the Secondary Aquifer Zone thins significantly west of Rocky's domestic drinking water well AGE infers from the results of the April CPT "grab" ground water sampling program that • Methanol has impacted ground water only in the lower Second and Rocky's Upper Zones in P13, located at the north margin of the Flag City Chevron site The methanol may not be related to the Flag City Chevron site The lack of other detectable analytes in P13 samples limits the northern margin of the MTBE-impacted ground water plume in the Second, Rocky's Upper and Secondary Aquifer Zones • Ground water in the lower Second, Rocky's Upper and the Secondary Aquifer Zones underlying the Flag City Chevron UST area(P 14)has not been impacted by any of the target analytes, establishing a vertical limit to the plume near the inferred source area • o None of the analytes of concerned were encountered in ground water samples collected from the First, Second, Rocky's Upper or the Secondary Aquifer Zones in P15, located midway between the Flag City Chevron site and the municipal water wells CSA-1 and CSA-2 on the east, establishing an eastern limit to the plume of impacted ground water • Ground water was found to be impacted in the Second, Rocky's Upper and Secondary Aquifer Zones in P16, located near the Rocky's Restaurant domestic well MTBE was detected in all three zones, ethanol in two upper zones and TBA only in the Second Zone • Ground water was also impacted in the lower Second, Rocky's Upper and the Secondary Aquifer Zones in P 17, located midway between the Rocky's Restaurant domestic well and the Three B's domestic well, west of the Flag City Chevron site The results of the May 2000 Geoprobe investigation of shallow soil and ground water on-site show both media to be impacted in the UST and dispenser areas AGE interprets the results to show that the panless middle and southern dispenser areas, the southeast corner of the UST pit and the storm drain line are the probable source areas for the TPH-g, TPH-d and MTBE in the subsurface on the site It is not known whether the release is from minute leaks in the system that are not revealed via . tightness tests, washdown of spilled fuel, or that both or other causes have contributed Adianced CeoEns ironmental Inc