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' 23 June 2003 AGE-NC Project No 00-0769 ' Page 4 of 13 bentonite transitional seal was installed between the filter pack intervals to minimize the potential ! for hydraulic influence from the other water bearing zones encountered in the monitoring well The bentonite seal was formed by pouring 318-inch, coated bentonite pellets into the annulus and ! allowing them to settle on the filter pack The bentonite pellets were allowed to hydrate for a minimum of one-half hour prior to the Installation of the next filter pack The second filter pack was added from the base of the next screen Interval to the upper portion of the screen Interval After ' installation of the filter pack, bentonite pellets were placed above the filter pack to the next screen interval This process was continued to above the last screen Interval and the remaining annular space was filled to near surface grade with a cement grout The grout mixture consisted of Type 1/11 portland neat cement with not more than 6 gallons of water per 94-pound sack of cement Each of the CMT monitoring wells (MW-4 through MW-9) was completed utilizing the same ! construction procedures for each individual well As-built well diagrams are included in Appendix C 3 14 Monitoring Well Development Utilizing a Watera inertial pump consisting of a dedicated 318-inch outer diameter, length-discrete polyethylene hose equipped with a ball-valve water tip , monitoring wells MW-4 and MW-5 were developed on 10 September 2002, monitoring well MW-6 was developed on 14 October 2002, monitoring well MW-9 was developed on 15 October and monitoring wells MW-7 and MW-8 were developed on 16 October 2002 Purge water was extracted in each chamber by lowering and raising the 318-inch polyethylene hose through the water-charged screen section Temperature, pH and conductivity of purged ground water were measured using a Oakton water analyzer Ground water was purged from each monitoring well until ground water was visually sediment free and pH, conductivity and temperature had stabilized Field sheets and data are included in Appendix D Purged water was temporarily stored on-site in 55-gallon DOT-approved H-17 storage drums pending proper disposal ! 3 15 Well Head Survey ' On 21 November 2002, a Cdliforma state-licensed survey engineer from Baumbacb &Piazza, Inc surveyed the elevation of a reference point on the top of the casings of ground water monitoring wells MW-6 through MW-9 to the nearest 0 01-foot relative to City of StocktonBenchMark#179, ' surveyed at 25 86 feet above mean sea level (MSL) Due to accessibility issues, monitoring wells MW-4 and MW-5 could not be surveyed The results of the monitoring well survey are contained in Table 2 The surveying report is presented in Appendix E ! Yi • ! Advanced GeoEnvironmental,Inc