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05 July 2005 AGE-NC Project No. 95-0137 Page 6 of 8 4.0. FIELD PROCEDURES All field procedures will be supervised by a California Professional Geologist. Procedures for the advancement of soil borings,ground water sampling,monitoring well installation and development, equipment decontamination,and sample shipment are outlined below. 4.1. DRILLING Proposed monitoring well borings will be completed using hollow stem drilling techniques. Soil cuttings recovered from the borings will be visually classified by a qualified geologist in accordance with the Unified Soil Classification System(USCS).Soil cuttings will be temporarily containerized in plastic and stored on-site. 4.2. MONITORING WELL INSTALLATION Following completion of drilling of each soil boring,a 2-inch diameter Schedule 40 PVC 0.020-inch slotted well screen and casing with#3 Lonestar sand filter pack will be installed.AGE's extensive experience installing monitoring wells has shown those materials generally result in wells that can be surged and developed to produce ground water with minimal sediment.A 20-foot section of well screen will be installed in each well, extending approximately 15 feet below and 5 feet above the top of the ground water table. An air tight, locking well cap will be placed on the top of each well casing. The well casing, filter pack and sealing materials will be placed into the borehole through the interior of the air rotary casing. After installing the well casing, filter pack material 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 thick bentonite seal will be placed above the filter pack to minimize 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 the chips 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 I/II portland neat cement and Advanced GeoEnvironmental.Inc.