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01 September 1999 <br /> AGE-NC Project No 97-0301 <br /> Page 8 of 10 <br /> 43 WELL COMPLETION <br /> Soil borings will be single-completed as ground water monitoring wells utilizing 2-inch diameter <br /> schedule 40 polyvinylchloride (PVC) 0 010-inch slotted well screen and blank well casing Based <br /> on geologic/hydrogeologic conditions, a 20-foot length of well screen is anticipated for installation <br /> of monitoring wells, the bottom of the screen interval will be placed 15 feet below the water table <br /> A proposed well construction diagram is depicted in Figure 3 <br /> ' After installing the well casing, filter pack material consisting of pre-washed #2/12 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 /> 1 Additional sand will be added if settling occurs <br /> A nominal two-foot bentonite seal (bentonite chips) will be placed above the filter pack to minimize <br /> ' the potential for grout penetration into the screened section of the well The bentonite seal will be <br /> formed by pouring bentonite chips into the annulus and allowing them to settle on the filter pack <br /> Bentonite chips will be hydrated using approximately five gallons of tap water The bentonite chips <br /> lie NN ill be allowed to 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 I/1I 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 /> 44 WELL DEVELOPMENT <br /> De%elopment 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 /> ill be continued until field parameter(pH, electrical conductivity, and temperature) readings have <br /> stabilized and purged water is visually sediment-free <br /> 45 EQUIPMENT DECONTAMINATION <br /> All sampling tools used for sample collection will be thoroughly rinsed with clean water after being <br /> «-ached with a solution of Alconoa A11 down-hole drilling and sampling equipment will be pressure <br /> ashed prior to starting the boring <br /> ' Adianced GeoEmironmcnlal Inc <br />