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t05 July 2000 AGE-NC Project No 00-0696 Pages 7 of 9 ' 4 2 MONITORING WELL INSTALLATION Following completion of drilling of each pilot boring, a 2-inch diameter Schedule 40 PVC 0 010- inch slotted well screen and casing will be installed A 15-foot section of well screen will be installed in each well, extending approximately 10 feet below and 5 feet above the top of the ground water table 1 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 #2112 Lonestar sand will be added from the bottom of the borehole to approximately two feet above the screened interval Following placement of the filter pack, the well will be surged to assist in settling the filter pack Additional sand will be added if settling occurs An nominal two-foot thick bentonite seal will be placed above the filter pack to minimize the potential of 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 them to settle on the filter pack Bentonite chips will be hydrated using five gallons of water The bentonite chips will be allowed to hydrate for a minimum of one-half hour prior to grouting 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 Type I/II portland neat cement and not more than 6 gallons of water per 94-pound sack of cement The grout will be placed by pumping through tremmie pipe The PHS-EHD will be notified for grout inspection at least 72 hours prior to conducting grouting procedures A typical monitoring well diagram is illustrated on Figure 3 Following completion of the monitoring wells, well elevations and locations will be surveyed by a California-licensed surveyor 43 WELL DEVELOPMENT AND SURVEY Development will consist of a combination of bailing to remove the mayor portion of fine-grained sediment from inside the well, surging to flush out or draw in sediment from the filter pack, and additional bailing to finish the removal of sediment Development activities will be continued until field parameter(pH, electrical conductivity, and temperature) readings have stabilized Additionally, the top of each well casing will be surveyed for elevation by a licensed surveyor r • Advanced GcoEnvi ron mental,Inc