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s 16 September 1998 AGE-NC Project No. 95-0197 Page 5 of 7 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 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•procedure to a DTSC-certified . laboratory. 3.2. MONITORING WELL INSTALLATION . The monitoring well.borings'will be completed using hollow=stein'auger drilling techniques. f Following completion of drilling the boring, a 2-inch diameter Schedule 40 PV: 0.010-inch lotted well screen and casing will be'installed. A 15-foot section of well screen will be in each well,extending approximately 10 feet below and five feet above the top of the ground water table. The 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 #2112 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 approximately two foot 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 annulus 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 tote for a minimum of one-hal hour prior to inserting the second well casing. The same installation procedures will apply for both.the deep screened:interval'and the'shallow screened interval. Following hydration of bentonite chips;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 will be placed by pumping through tremmie pipe. A proposed well construction;diagram is illustrated in Figure 3. Grouting procedures will be inspected by PHS-EHD personnel. Following completion of the monitoring wells, well elevations and locations will be surveyed-by a California-licensed surveyor. . Advanced GeoEnvironinentat,.Inc.