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i <br /> 17 March 1997 <br /> AGE-NC Project No. 95-0100 <br /> Page 5 of 7 <br /> •4.4. CONFIRMATION SOIL BORINGS <br /> When the•projected clean-up period has been completed, or efficiency of the unit has declined, then <br /> strategically placed confirmation soil borings will be advanced within the projected area of soil <br /> contamination. The confirmation soil borings will serve to approximate remaining petroleum <br /> hydrocarbon levels still'present beneath the site. <br /> Soil borings will be advanced to a maximum depth of 35 feet utilizing a van-mounted Geoprobe <br /> 5400 soil probing machine and 1.125-inch rods. Soil samples will be collected at five-foot intervals <br /> beginning at 5 feet below site grade (bsg)using a Geoprobe soil assembly and associated 1.125-inch <br /> diameter brass sleeves. The middle brass sleeve will be removed and the ends covered with Teflon <br /> tape or aluminum sheets, sealed with plastic end caps, secured with tape, and immediately placed <br /> in a chilled container. Each sample sleeve will be labeled with the following; boring location, depth, <br /> time, date, sampler's initials, and transported to a state certified laboratory for analysis of TPH-g, <br /> BTE&X and MTBE. <br /> . 4.5. REMEDIATION CLEAN-UP GOALS <br /> A proposed attenuation factor or clean up goal for the soil at the site is the removal of 90 % of the <br /> petroleum hydrocarbons dispersed in the.soil in the investigation area. The reduction of the <br /> hydrocarbons and the remedial progress will be measured from additional soil samples, collected <br /> from below former dispenser area. <br /> The quantity of hydrocarbons removed will be measured by calculating a quantity removed by the <br /> SVE-system and a real time mass balance against an initial mass balance calculation of TPH-g and <br /> BTE&X compounds in the soil, at the site. <br /> 5.0. PROCEDURES <br /> 5.1. SVE UNIT OPERATION AND MONITORING <br /> For the installation and monitoring of the soil vapor extraction system,the following procedures will <br /> be performed: <br /> 1. Install the subsurface PVC piping and place and connect SVE unit within a secured'area. <br /> 2. VES system will be inspected by the PHS-EHD prior to operation. <br /> 3. Monitor the SVE system daily for approximately two weeks; collect OV readings using a <br />