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31 July 2000 <br /> AGE-NC Project No. 98-0468 ' <br /> Page 9 of 11 <br /> 4.3.' WELL COMPLETION <br /> Soil borings will be single-completed as ground water monitoring wells utilizing 2-inch diameter <br /> .schedule 40 polyvinylchloride (PVC) 0.020-inch slotted.well screen and blank well casing. Based <br /> on geologic/hydrogeologic conditions," a 15-foot length of well screen is anticipated for installation <br /> of the shallow monitoring wells, the deep monitoring well will be completed with a 5-f6ot lengh of <br /> well screen; the bottom of the screen interval will be placed 15 feet below the water table. A <br /> i <br /> proposed well construction diagram is depicted in Figures 5 and 6. <br /> i - <br /> After installing the well casing, filter pack material consisting of pre-washed #3 Lonestar sand will <br /> be added from the bottom of the borehole to approximately two feet above the screened interval. <br /> Following placement of the filter pack, the well will be surged to assist in settling the filter pack. <br /> Additional sand will be added if settling occurs. <br /> A nominal two-foot bentonite seal will be placed above the filter pack to minimize the potential for <br /> grout penetration into the,screened section'of the well. The bentonite seal will be formed by pouring <br /> bentonite chips into the annulus and allowing them to settle on the filter,pack. Bentonite chips will <br /> • be hydrated using approximately five gallons of,tap water. The bentonite chips will be allowed-to <br /> hydrate for a minimum of one-half hour prior to grouting. - <br /> The remaining annular space will be filled to the ground surface with a cement grout. The grout <br /> mixture will consist of Type PH Portland neat cement.and not more than 6 gallons of water per 94- . <br /> •pound sack of cement. The grout will be placed by pumping through tremmie pipe. A grouting <br /> inspection will be scheduled with PHS-EHD personnel. <br /> 4.4. WELL DEVELOPMENT <br /> Development of the proposed wells will consist of a combination of bailing with a stainless steel <br /> bailer to remove the mayor portion of fine-grained sediment from inside the well, surging to flush <br /> out or draw in sediment from the filter pack and additional ground water evacuation (purging) with <br /> a submersible pump to finish the removal of fine-grained sediment.Developmental purging activities <br /> will be continued until field parameter(pH, electrical conductivity, and temperature)readings have <br /> stabilized and purged water is visually sediment-free. <br /> Adwnced Geo£nvirorimenlal,Inc. <br />