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. 31 August 2004 AGE-NC Project No 95-0141 Page 6 of 6 • HU4 - A 5-foot length of well screen will be installed from 113 to 118 feet bsg After installing the well casing, filter pack material consisting of pre-washed#3 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 A nominal two-foot bentonite seal (bentonite chips) will be placed above the filter pack of the shallow monitoring well to minimize the potential for grout penetration into the screened section of the well A four-foot bentonite seal will be utilized for wells screened through HU2 and HU4 The bentonite seal will be formed by pounng bentonite chips into the annulus and allowing them to settle on the filter pack The bentonite chips will be hydrated using approximately five gallons of tap water and will be allowed to hydrate for a minimum of one-half hour prior to grouting The remaining annular space will be filled to within a foot of the ground surface with a cement grout The grout mixture will consist of Type LII 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 tremae pipe A grouting inspection will be scheduled with EHD personnel A traffic-rated well box will be installed over the remaining annular space Proposed groundwater monitoring well construction diagrams are depicted in Figures 5, 6 and 7 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, each well-head elevation will be surveyed by a licensed surveyor 4 4 EQUIPMENT DECONTAMINATION All sampling tools used for sample collection will be thoroughly washed with a solution ofAlconox and rinsed with clean water prior to each sampling location All probing rods will be cleaned prior to advancement at each boring location Hollow-stem augers will be steam-cleaned prior to each boring Advanced GeoEnvironmental,Inc