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Mr Kyle Christie Project 0805-147 01 <br /> August 4, 1995 <br /> Page 3 <br /> Groundwater Monitoring Well Installation <br /> In the event that hydrocarbons are present in soil samples collected from the borings <br /> downgradient from the USTs (using a photoioruzation detector [PID] and field <br /> observations), and based on subsurface conditions, EMCON will observe a licensed well <br /> driller redrill the boring with a 10-inch-diameter auger and two drill 10-Inch-diameter soil <br /> borings near the northwestern and southeastern property boundaries (see Figure 2). The <br /> borings will be drilled to a depth of approximately 55 feet bgs or 15 feet below fust <br /> encountered groundwater However, if a 5-foot thick clay layer Is encountered less than <br /> 15 feet bgs, the drilling will be terminated within the clay unit <br /> Three 4-inch-diameter groundwater monitoring wells will be Installed in the borings The <br /> wells will be constructed using 0 02 slotted screen The 0 02 screen will be placed from <br /> approximately 15 feet below first encountered groundwater and will extend up to five feet <br /> above first encountered groundwater Number 3 sand will be used as the filter pack <br /> Undisturbed soil samples will be collected from the two soil bonngs drilled near the <br /> northwestern and southeastern property boundaries using the methods described above In <br /> addition, two soil samples from each boring will be submitted to an approved state <br /> certified laboratory and analyzed for TPHG and BTEX using EPA Methods 8015 and <br /> 8020, respectively <br /> Vapor Extraction Well Installation <br /> In the event that hydrocarbons are present in soil samples collected from the boring <br /> located at the northwest corner of the tank complex (using a PID and field observations) <br /> and based on subsurface conditions, EMCON will observe a licensed well driller redrill the <br /> boring with a 10-Inch-diameter auger (see Figure 2) The borings will be drilled to a depth <br /> of approximately 40 feet bgs or to fust encountered groundwater <br /> One 4-uich-diameter vapor extraction well will be installed in the boring The well will be <br /> constructed using 20 feet of 0 10 slotted screen Pea gravel will be used as the filter pack <br /> Well Development and Sampling <br /> If groundwater monitoring wells are installed, EMCON will develop and sample the <br /> groundwater monitoring wells In addition, a licensed surveyor will be contracted to <br /> survey the location of the wells with respect to mean sea level The wells will be placed on <br /> a quarterly groundwater monitoring program and analyzed for TPHG and BTEX using <br /> iEPA Methods 8015 and 602, respectively EMCON's field procedures are included in <br /> Attachment A <br /> SAC\N\Pd010805108051470IAN-941dms I <br />