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— 10 October 1999 AGE-NC Project No. 99-0559 Page b of S Following sample collection, each preserved sample sleeve will be labeled with the boring location, — depth, time, date and sampler's initials. Appropriately sealed and labeled samples will be placed under ice in a chilled container and will be transported under chain-of-custody to a DHS-certified laboratory. 4.2. IN-SITU GROUND WATER SAMPLING PROCEDURES For the collection of grab ground water samples, soil borings will be advanced to the top of the — ground water table as identified by collection of a saturated soil sample. Once ground water has been encountered, the augers will be advanced two to three feet into the water-bearing zone. Each ground water sample will be extracted by lowering a polyethylene disposable bailer through the hallow �. center of the augers. Samples for TPH-g, BTEX, and fuel oxygenate analyses will be collected into laboratory-supplied, 40-m1 VOA vials containing 0.5-m1 hydrochloric acid as sample preservative. Ground water samples for TPH-d will be collected into laboratory-supplied 1-liter glass ambers. The labeled sample containers will be placed under ice in a chilled container and transported under chain- of-custody to a DHS-certified laboratory. 4.3. MONITORING WELL INSTALLATION PROCEDURES _ Monitoring well pilot borings will be advanced using hollow-stem auger drilling techniques. Relatively undisturbed soil samples will be collected at five-foot intervals in each of the borings using a California modified split-spoon sampler fitted with 2-inch diameter, 5-inch long brass sleeves. Soil sample handling will be consistent with the procedures presented in Section 4.1. Following completion of drilling the boring, a 2-inch diameter Schedule 40 PVC 0.010-inch slotted well screen and casing will be installed. Twenty feet of screen will be installed in each well. extending approximately 15 feet below and five feet above the top of the ground water table. The well casing, filter pack and sealing materials will be placed into the borehole through the interior of the hollow-stem augers. After installing the well casing, filter pack material consisting of pre- washed 42/12 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 well will be surged to assist in settling the filter pack. Additional sand will be added if settling occurs. A nominal two-foot bentonite seal will be placed above the filter pack to minimize potential for _ grout penetration into the screened section of the well. The bentonite seal will be formed by pouring bentonite chips into the annular space between the auger and the well casing and allowing them to settle on the filter pack. Bentonite chips will be hydrated using five gallons of water. The bentonite Advanced CeoEnN ironmenlal,Inc.