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07 June 2012 <br /> AGE-NC Project No. 95-0184 <br /> Page 9 of 14 <br /> The well casings,filter pack and sealing materials will be placed into the boreholes through <br /> the interior of the hollow-stem augers. After installing the well casings, filter pack material <br /> consisting of pre-washed #3 Lonestar sand will be added to the remaining annular space <br /> from the bottom of the borehole to approximately one or two feet above the well screen <br /> intervals. <br /> A two- or three-foot bentonite seal will be placed above the filter packs to minimize grout <br /> penetration into the screened section of the well. The bentonite seal will be formed by <br /> pouring bentonite chips (SVE well) or pellets (]AS wells) into the annular space between <br /> the auger and the well casing and allowing them to settle on the filter pack. Bentonite will <br /> be hydrated using a sufficient volume of water. Bentonite will be allowed to hydrate for a <br /> minimum of one-half hour prior to grouting. <br /> Remaining annular space above the bentonite seal will be filled to within one foot of the <br /> ground surface with a cement grout. The grout mixture will consist of Type 1/11 Portland neat <br /> cement and not more than 6 gallons of water per 94-pound sack of cement. The grout will <br /> be placed by pumping through tremie pipe. A traffic-rated well box will be installed overthe <br /> wells, in accordance with County regulations. EHD will be notified for grout inspection at <br /> least 48 hours prior to conducting grouting procedures. As-built well diagrams are <br /> illustrated in Figures 5 and 6. <br /> 4.2. WELL ELEVATION SURVEY <br /> Following completion of well installations, a reference point will be marked on the top of <br /> each well head, and surveyed by a California licensed surveying engineer to the nearest <br /> 0.01 foot to determine the elevation relative to a surveyed benchmark and to determine <br /> GPS coordinates for tracking on the State Water Resource Control Board (SWRCB) <br /> GeoTracker database system. <br /> 4.3. SVE/IAS PIPING NETWORK INSTALLATION <br /> For the SVE system, a network of three-inch diameter, schedule 40 PVC piping will be <br /> installed 12-inches below surface grade and where possible, SVE/IAS piping will be routed <br /> in the same trench or above ground. The three-inch PVC piping will be routed from each <br /> SVE well head and a three-inch connection and PVC ball valve will be installed at each <br /> SVE well pipe creating a manifold, so that vapor can be drawn from each well <br /> independently; the manifold of three-inch piping will then be directly connected to the SVE <br /> unit. <br /> Advanced GeoEnvironmental,Inc. <br />