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N • 21 September 1998 AGE-NC Project No 97-0290 Page 6 of 8 Soil pilot borings for morutonng wells will be advanced using hollow-stem auger drilling techniques Soil borings will be continuously sampled using continuous core sampler and drive samples collected at five-foot intervals Relatively undisturbed soil samples will be collected in each of the borings using a California modified split-spoon sampler fitted with 2-inch diameter, 6-inch long brass sleeves Upon removal from the sampler,the sample sleeve is separated with a clean soil knife The exposed ends of the second 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 USCS Additionally, soil samples will be field screened for the presence of volatile organic compounds using an 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 6 MONITORING WELL COMPLETION iFollowing completion of drilling the pilot 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 15 feet below and five feet above the top of the ground water table The casing, filter pack and sealing matenals 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 A nominal 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 to hydrate for a minimum of one-half hour prior to grouting The remaining annular space will be filled to the ground surface with a cement grout The grout mixture will consist of Type I/1I portland neat cement and not more than 6 gallons of water per 94- pound sack of cement The grout may be placed by pumping through tremmie pipe, if necessary Grouting procedures will be inspected by PHS-EHD personnel Following completion of the monitoring wells, well elevations and locations will be surveyed by a Advanced GeoEnvironmentsl,Inc