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08 November 2000 AGE-NC Project No. 95-0142 Page 8 of 9 then be immediately placed in a chilled container for transportation under chain of custody to a state- certified laboratory. Each sample sleeve will be labeled with the boring location, sample depth, sample time, sampling date and sampler's initials. Duplicate samples will be monitored for the presence of organic vapor using a photo-ionization detector(PID: Thermo Environmental 580A, 10.0 eV, calibrated to isobutylene) and will be visually described on boring logs using the Unified Soil Classification System(USCS). All sampling tools and brass sleeves used for sample collection will be thoroughly rinsed with clean water after washing with a solution of Alconox. All hollow stem augers will be steam-cleaned prior to advancement of each borehole. 4.3. WELL COMPLETION The final 15-inch diameter pilot borings will be single-completed as a ground water extraction well utilizing 6-inch diameter schedule 40 polyvinylchloride (PVC) 0.020-inch slotted well screen and blank well casing.A 30-foot length of well screen is anticipated for installation of the monitoring well from 30 feet to 60 feet bsg. A proposed monitoring well construction diagram is depicted in Figure 3. After installing the well casing in each pilot boring, a filter pack material consisting of even proportions of pre-washed #2/12 Lonestar sand and 3/8" gravel (large sand) 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 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 annular space between the well casing and the boring wall 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 I/II 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 tremmie pipe. A grouting inspection will be scheduled with PHS-EHD personnel. Advanced Geo Environmental,Inc.