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16 May 2000 <br /> AGE-NC Project No. 95-0173 <br /> Page 4 of 6 <br /> schedule 40 polyvinylchloride (PVC) 0.010-inch slotted well screen and blank well casing. Based <br /> on geologic/hydrogeologic conditions, a 10-foot length of well screen is anticipated for installation <br /> of monitoring wells; the bottom of the screen interval will be placed at approximately 90 feet bsg. <br /> A proposed well construction diagram is depicted in Figure 3. <br /> After installing the well casing, filter pack material consisting of pre-washed#2112 Lonestar sand <br /> will 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 (coated bentonite pellets:pell plug)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 chips into the annulus and allowing them to settle <br /> on the filter pack. The bentonite chips will be allowed to hydrate for a minimum of one-half hour <br /> 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 UIl 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 /> 3.3. WELL DEVELOPMENT <br /> Development of the proposed wells will consist of a combination of bailing with a stainless steel <br /> bailer to remove the major 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 /> 3.4. EQUIPMENT DECONTAMINATION <br /> All down-hole drilling and sampling equipment will be pressure washed prior to starting the boring. <br /> 3.5. GROUND WATER MONITORING PROCEDURES <br /> �. Groundwater sample collection will be performed in accordance with PHS-EHD guidelines (San <br /> Advanced GcoEnvlronmental,Inc. <br />