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CLEARWA TER <br /> G R O U P, I N C <br /> En v..onvrentat Se,v,c,s <br /> samples collected off-site confirmed the presence of a potential release at the 7-11 facility to the <br /> east <br /> Clearwater Group, Inc was retained in early 1995 to continue the groundwater sampling program <br /> initiated by McLaren/Hart Quarterly sampling of the five on-site monitoring wells has continued <br /> throughout the course of this project Results of sampling document the occasional presence of <br /> extremely low concentrations of gasoline-range hydrocarbons Analysis of groundwater samples <br /> for concentrations of MTBE has been conducted for six consecutive quarters No sample has <br /> shown MTBE concentrations above instrument detection limits <br /> Recent Activities <br /> While MW-3, 4, and 5 have been shown to exist downgradient of the former UST basin, staff at <br /> PHS/EHD requested that a sample from a well on the Southland property/downgradient from MW- <br /> 3 be tested prior to consideration of this site for closure Southland installed a well in the desired <br /> • location in September, 1997 (Figure 1) Results of analysis of a sample collected from this well <br /> indicated that the sample contained no detectable concentrations of fuel hydrocarbon contamination <br /> Results of sample analysis are presented in Attachment i <br /> Complete copies of the referenced reports have been provided as an attachment to this letter <br /> (Attachment 2) <br /> Existing Environmental Site Conditions <br /> Soil <br /> Results of site characterization activities indicate that a limited volume of soil containing <br /> hydrocarbon contamination remains beneath the subject site The area containing residual <br /> hydrocarbons is restricted to that within the immediate vicinity of sample UGS collected during <br /> tank removal activities in 1992 Results of analysis of soil samples collected by Kennedy/Jenks in <br /> 1995 demonstrate the presence of residual hydrocarbons to a depth of approximately 25 feet below <br /> ground surface (bgs), though the highest concentrations were noted at approximately 14 feet bgs <br /> Using the values presented in the Kennedy/Jenks May, 1995 report, it is conservatively estimated <br /> . that 11 gallons of gasoline were present in soil beneath the former tank excavation at the time of <br /> • 3 <br />