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15 September 1999 AGE-NC Project No. 97-0369 Page 7 of 9 immediately covered with Teflon or aluminum sheets, sealed with plastic end caps, secured with tape and immediately placed in a chilled container for transportation 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. During sampling activities, sample duplicates 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 ,N7111 be steam-cleaned prior to advancement in each borehole. 4.3. WELL COMPLETION Soil borings xvill be single-completed as ground water monitoring wells utilizing 2-inch diameter schedule 40 polyvinylchloride (PVC) 0.010-inch slotted well screen and blank well casing. Based on geologie/hydrogeologic conditions, a 20-foot length of well screen is anticipated for installation of monitoring wells; the bottom of the screen interval .vill be placed 15 feet below the water table. A proposed well construction diagram is depicted in Figure 3. After installing the well casing, filter pack material consisting of pre-washed #2/12 Lonestar sand will be added from the bottom of the borehole to approximately two feet above the screened interval. Following placement of the filter pack, the Nvell will be surged to assist in settling the filter pack. Additional sand will be added if settling occurs. A nominal two-foot bentonite seal (bentonite chips) 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 chips into the annulus and allowing them to settle on the filter pack. Bentonite chips will be hydrated using approximately five gallons of tap water. The bentonite chips will be allowed to hydrate for a minimum of one-half hour prior to grouting. The remaining annular space will be filled to 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 «-ill be placed by pumping through tremmie pipe. A grouting inspection xvill be scheduled with PHS-EHD personnel AdvaiwedGcoEnNironmcntal,Inc.