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Y - 09 June 2000 AGE-NC Project No. 98-0497 Page 7 of-10 drilling techniques. Relatively undisturbed soil-samples will be collected at five-foot intervals in each of the borings using'a.California modified split-spon sampler fitted with-2-inch diameter, 6- inch.long brass sleeves.Upon removal from the sampler,)the sample sleeve is separated with a clean knife. The exposed ends of the sleeve will be covered"With Teflon sheets, capped and sealed with tape. Soils encountered in the borings will be visually classified by an AGE geologist in accordance with the Unified Soil Classification System(USCS).Additionally,soil'samples will be field screened for the presence of volatile organic compounds using ark OVM: Following sample collection,each preserved sample sle&e will be labeled-with the boring.location, . depth, time, date and sampler's initials. Appropriately;s tiled 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. MONITORING WELL INSTALLATION Following completion of selected-borings, a 2-inch diameter Schedule 40 PVC 0.010-inch slotted well screen and casing will be installed. A 20-foot sect ion of well screen will be installed.in each well, extending approximately 12 to 15 feet below and 5 to 8 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 bo om 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 bentoniteseal will be placed above the filter pack to minimize the potential of grout penetration into the screened section othe well.The bentonite seal will be formed by pouring bentonite chips into the annular space betwee 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 mini=ni of one-half hour prior to grouting. . . The remaining annular space above the bentonite seal w 11 be filled to within one foot of the ground surface with a cement grout. The grout mixture will co isist of Type MI portland neat cement and not more than 5 gallons of water per 94-pound sack of ce ent. The grout will be placed by pumping through tremmie pipe. The PHS-EHD will be notified for grout inspection at least 72 hours prior to - conducting grouting procedures. Following completion of the monitoring wells,well ele cations and,locations will be surveyed by a California-licensed surveyor. Advanced GeoEnvironmental,Inc.