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26 October 2000 <br /> AGE-NC Project No 95-0128 <br /> Page 8 of 10 <br /> blank well casing A 20-foot length of well screen is anticipated for installation of the monitoring <br /> well A proposed monitoring well construction diagram is depleted in Figure 3 <br /> After installing the well casing in each pilot boring, a filter pack material consisting of pre-washed <br /> #3 Lonestar sand will be added through the augers over the screen interval to approximately two feet <br /> above the screened interval Following placement of the filter pack,the well will be surged to assist <br /> in settling the filter pack Additional sand will be added if settling occurs <br /> The 15-inch diameter pilot boring will be single-completed as a ground water extraction well <br /> utilizing 6-inch diameter schedule 40 polyvinylchloride (PVC) 0 020-inch slotted well screen and <br /> blank well casing A 20-foot length of well screen is anticipated for installation of the monitoring <br /> well A proposed monitoring well construction diagram is depicted in Figure 4 <br /> After installing the well casing in each pilot boring, a filter pack material consisting of even <br /> proportions of pre-washed#3 Lonestar sand and 5/16" gravel will be added through the augers over <br /> the screen interval to approximately two feet above the screened interval Following placement of <br /> the filter pack, the well will be surged to assist in settling the filter pack Additional filter pack will <br /> • be added if settling occurs <br /> A nominal two-foot bentonite seal (pell plug-coded bentonite pellets) will be placed above the filter <br /> pack to minimize the potential for grout penetration into the screened section of the well The <br /> bentonite seal will be formed by pouring bentonite pellets into the annulus and allowing them to <br /> settle on the filter pack The bentonite pellets will be allowed to hydrate for a minimum of one-half <br /> hour prior to grouting <br /> The remaining annular space will be filled within one foot of the ground surface with a cement grout <br /> The grout mixture will consist of Type I/11 portland neat cement and not more than 6 gallons of water <br /> per 94-pound sack of cement The grout will be placed by pumping through tremmie pipe A <br /> grouting inspection will be scheduled with PHS-EHD personnel <br /> 43 WELL DEVELOPMENT/SAMPLING <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 The newly ground water monitoring well will <br /> be sampled quarterly, with the current well network <br /> Advanced GeoEnvironmental,Inc <br />