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I , 20 April 2007 AGE-NC Project No. 95-0167 Page 6 of 10 and labeled samples will be placed under ice in a chilled container and will be transported under COC to a DHS-certified laboratory for analysis. The soil in the two remaining sleeves will be visually classified by an AGE geologist in accordance with the Unified Soil Classification System II � �SCS) and field-screened for the presence of volatile organic compounds using an organic vapor h meter (OVM) equipped with aphoto4onization detector (PfD : fbermo Environmental 580B, I O.OeV G [or equivalent] , calibrated to isobutylene). I, 4.2 OBSERVATION WELL INSTALLATION Following completion of the observation well pilot boring, one 2-inch diameter Schedule 40 PVC 0.020-inch slotted well screen and casing will be installed adjacent to boring P6. A 15 foot section of well screen will be installed, screened from approximately 5 to 20 feet bsg. The well casing, filter pack and sealing materials will be placed into the borehole through the interior of the hollow-stem augers. After installing the well casing, filter pack material consisting of pre-washed #3 Lonestar sand or coarse sand will be added to the remaining annular space from the bottom of the borehole to approximately one foot above the screened interval. A nominal two-foot thick bentonite seal will be placed above the filter pack to minimize grout penetration into the screened section of the well. The bentonite seal will be formed by pouring bentonite chips into the annular space between the auger and the well casing and allowing the chips to settle on the filter pack. The bentonite chips will be allowed to hydrate for a minimum of one-half p hour prior to grouting using a minimum of five gallons of water. V The remaining annular space above the bentonite seal will be filled to within one foot of the ground surface with a cement grout. The grout mixture will consist of Portland, neat cement and not more i! than 6 gallons of water per 94-pound sack of cement. The grout will be placed by pumping through a tremie pipe. The EHD will be notified for grout inspection at least 48 hours prior to conducting grouting procedures. An observation well diagram is illustrated on Figure 4. 4.3 . GROUNDWATER EXTRACTION WELL INSTALLATION AND PILOT TESTING Following completion of drilling of the extraction well pilot boring, a 4-inch diameter Schedule 40 PVC 0.020-inch slotted well screen and casing will be installed in the borehole. The well-screen section will be 20-feet in length, extending from approximately 15 feet to 35 feet bsg. The well casing, filter pack and sealing materials will be placed into the borehole through the interior of the augers. After installing the well casing, filter pack material consisting of #3 Lonestar sand or coarse sand will be added from the bottom of the borehole to approximately one foot above the A&anred GeoEnviron entnl Inc.