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I11 November 2004 i AGE-NC Project No 99-0624 ' Page 12 of 13 ' extraction well utilizing a 20-foot section of 4-inch diameter Schedule 40 PVC 0 020-Inch slotted well screen and blank well casing extended to surface grade Proposed well construction diagrams are depicted on Figures 11,12 and 13 IAfter Installing the well casing in each pilot boring, a filter pack material consisting of pre-washed #2/12 Lonestar sand will be added through the augers over the screen interval to approximately two I feet above the screened Interval Following placement of the filter pack, the water wells will be surged to assist in settling the filter pack Additional sand will be added If settling occurs ' A nominal two-foot bentonite seal (bentonite pellets or chips) will be placed above the filter pack to minimize the potential for grout penetration into the screened section of the well The bentonite seal will be formed by pouring bentonite pellets Into the annulus and allowing them to settle on the ' filter pack The bentonite pellets will be allowed to hydrate for a minimum of one-half hour prior to grouting The remaining annular space will be filled to within one foot of the ground surface with a cement grout The grout mixture will consist of Type UII 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 a tremae pipe A grout inspection will be scheduled with SJCEHD personnel I Following completion of the monitoring wells, well elevations and locations will be surveyed by a California-licensed surveyor relative to a City of Lodi elevation benchmark 55 WELL DEVELOPMENT Development of the proposed ground water wells will consist of a combination of bailing with a stainless steel bailer 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 ground water evacuation I (purging) with a Waterra bailing pump to complete the removal of fine-grained sediment Developmental purging activities will be continued until field parameter readings (pH, electrical conductivity, and temperature) have stabilized and purged water is visually sediment free 5 6 GROUND WATER AQUIFER PUMPING TEST A 24-hour ground water aquifer pumping test will be conducted at the site to induce a decline in static water level in the newly Installed ground water extraction well (screened 55 to 75 feet bsg) IPressure transducers will be deployed, at a minimum, in wells MW-1,MW-2,MW-3 and MW-4 to • measure the difference in ground water levels before well pumping versus time during ground water Advanced GeoEnviron mental,Inc