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31 March 2000 AGE-NC Project No. 00-0699 Page 7 of 9 encountered in the borings will be visually classified by an AGE geologist in accordance with the Unified Soil Classification System(USCS).Additionally,soil samples with be field screened for the presence of volatile organic compounds using an organic vapor meter(OVM). 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 in a chilled container under ice and transported under chain-of-custody to a DHS-certified laboratory. 4.2. GRAB GROUND WATER SAMPLE COLLECTION For the collection of"grab"ground water samples,selected borings will be advanced approximately five feet into the ground water table as identified by collection of a saturated soil sample. Ground water will be allowed to enter the augers. Each ground water sample will be extracted by lowering a disposable bailer through the hollow stem augers into ground water. Samples will be collected, preserved and transported as described in Section 4.5.4. 4.3. MONITORING WELL INSTALLATION Following completion of drilling the boring,a 2-inch diameter Schedule 40 PVC 0.010-inch slotted well screen and casing will be installed. A 20-foot section of well screen will be installed in each well,extending approximately 12 to 15 feet below and five to eight 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 #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.well will be surged to assist in settling the filter pack. Additional sand will be added if settling occurs. An nominal two-foot thick bentonite seal will be placed above the filter pack to minimize the potential of 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 chips will be allowed to hydrate for a minimum of one-half hour prior to grouting. The remaining annular space above the bentonite seal will be-filled to within one foot of the ground surface with a cement grout. The grout mixture will consist of Type bII portland neat cement and not more than 6 gallons of water per 94-pound sack of cement. The grout will be placed by pumping Advanced GeoEnvironmental,Inc.