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The October 24, 1994 data validate the concentration data from the previous four sampling events <br /> (September 1993, December 1993, March 1994, June 1994) indicating non-detectable petroleum <br /> hydrocarbons in Site groundwater Based on these five quarters of no significant detections, the <br /> volume of groundwater impacted with petroleum hydrocarbons at the Site appears to be negligible <br /> It appears, based on a preliminary assessment performed on soil samples collected in June 1994, that <br /> active aerobic degradation of the residual hydrocarbon impacts to the sandy zone may be occurring <br />' resulting in the documented reduction and continued absence of petroleum hydrocarbons in Site <br /> groundwater <br />' An evaluation of groundwater chemical data in consideration of the observed water level and <br /> subsurface geologic data indicates that initial groundwater impacts from the petroleum hydrocarbons <br /> released at the Site were limited to the sandy zone between 62 and 80 feet below ground surface <br /> (bgs) Conservative benzene transport estimates of contaminant flow within this sandy zone indicate <br /> a migration rate of less than 15 feet per year <br /> In summary, since 1988 the Mayor Mart Site has been investigated and monitored for the distribution <br /> of chemicals of concern in site soils and shallow groundwater The removal of tanks and <br />' hydrocarbon affected soils was a significant remedial measure which apparently removed a critical <br /> source of petroleum hydrocarbons Present stable site conditions and the continued absence of <br /> benzene hydrocarbons in groundwater after five quarters of groundwater monitoring support our <br /> recommendation for regulatory Site closure <br /> SECOR Intemational Inc (SECORO) CRC Environmental Risk Management,Inc <br /> N0026 001 01 add 4 November 30 1994 <br />