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28 June 2001 AGE-NC Project No. 95-0103 Page 6 of 9 4.0. FIELD PROCEDURES All field procedures will be overseen by an AGE representative under the supervision of a California Registered Geologist. Procedures for the well installation, well development, dedicated low-flow pump installation, dedicated pressure transducer installation and pump and treat procedures are described below. 4.1. PILOT SOIL BORING Three pilot soil borings will be advanced at the site to a maximum depth of 30 feet bsg utilizing a truck-mounted hollow-stem drill rig. The three pilot soil boring will be established with 15-inch diameter hollow-stem augers for the ground water extraction well construction. Cuttings generated during drilling will be placed in DOT-approved 55-gallon drums. Rinseate will be containerized in properly labeled DOT-approved 55-gallon drums,and stored on-site in an area lacking public access. 4.2. WELL COMPLETION The 15-inch diameter pilot soil borings will be single-completed as a ground water extraction wells utilizing 6-inch diameter schedule 40 polyvinylchloride (PVC) 0.020-inch slotted well screen and blank well casing. A 20-foot length of well screen is anticipated for installation of the recovery wells. A proposed extraction well construction diagram is depicted in Figure 4. After installing the well casing in each pilot boring, a filter pack material consisting of even proportions of pre-washed#3 Lonestar sand and 3/a inch gravel will be added through the augers over the screen interval 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 filter pack will be added if settling occurs. A nominal two-foot bentonite seal (pell plug-coded bentonite pellets)will be placed above the filter pack to minimize the potential for grout penetration into the screened section of the well. The bentonite seal will be formed by pouring bentonite pellets into the annulus and allowing them to settle on the filter pack. The bentonite pellets will be allowed to hydrate for a minimum of one-half hour prior to grouting. The remaining annular space will be filled to within one foot of the ground surface with a cement grout. The grout mixture will consist of Type L9 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 a tremmie pipe or equivalent. A traffic-rated well box will be installed over each newly installed well. A grouting inspection will be scheduled with PHS-EHD personnel.