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1 <br /> ' VERIFICATION GROUNDWATER MONITORING PHASE <br /> ' FINAL REPORT <br /> FOR <br /> ' AMERICAN TRANSIT MIX COMPANY <br /> 651 SOUTH MAC ARTHUR BLVD. , TRACY CALIFORNIA <br /> 1 <br /> 1.0 INTRODUCTION <br /> ' This report presents results of the groundwater investigation <br /> conducted by RMC Lonestar's Environmental Department at the <br /> American Transit Mix Site in Tracy, California ( "the site" ; Figure <br /> ' 1) . This investigation was conducted as proposed in the <br /> "GROUNDWATER INVESTIGATION WORK PLAN" dated April 10 , 1990. The <br /> investigation focused on the potential impact to the groundwater <br /> caused by a release of petroleum hydrocarbons which was discovered <br /> during the removal of two underground fuel tanks at the site on <br /> September 27, 1989. <br /> I <br /> ' The Purpose of this investigation was to assess whether the <br /> excavation around the tank pit has removed all soils affected by <br /> the presence of petroleum hydrocarbons and whether groundwater has <br /> been affected. <br /> This report also includes the methods used to conduct this <br /> investigation, the results obtained, conclusions, and <br /> ' recommendations. <br /> ' 2.0 DRILLING AND MONITORING WELL INSTALLATION <br /> On September 9 , 1991 , three monitoring wells (MW-1 , MW-2 , and MW-3 ) <br /> ' were drilled and installed at the site by Spectrum Exploration Inc. <br /> using an 8-inch diameter hollow-stem auger. Well locations are <br /> presented in Figure 2. All three wells were drilled to 17 feet <br /> ' below surface grade. Observations were made during the advancement <br /> of each well boring regarding sediment types, groundwater depth, <br /> petroleum staining and odor. A Foxboro Century 88 OVA was used to <br /> ' detect volatile organic vapors. Field boring logs describing <br /> sediments encountered, observations regarding petroleum content, <br /> 1 � <br /> i <br /> I <br />