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08 December 1998 <br /> AGE-NC Project No 95-0144 <br /> i ' Page 3 of 7 <br /> f i <br /> "B" The well locations are shown on Figure 2 <br /> 24 SURVEYING <br /> On 24 September 1998, the casing elevations of the six new wells and MW-1 3 were surveyed to the <br /> nearest 0 01-foot relative to mean sea level as established at a City of Stockton Bench Mark (Table <br /> 2) Surveying was performed by Baumback & Piazza, Inc Since the casing elevations at the <br /> Madison and Van Buren sites were previously surveyed relative to an arbitrary bench mark, all <br /> ' casing elevations were recalculated relative to mean sea level based upon the resurveying of MW-13 <br /> 25 MONITORING WELL DEVELOPMENT <br /> Each well was surged during installation of the sand packs On 01 and 20 July 1998, additional <br /> ' monitoring well development was performed A PVC bailer was used to surge each well and to _ <br /> remove coarser sediments A, . two-stage purge pump was then used to remove additional sediments from each well until the purge water was essentially sediment-free Approximately 10 to 60 gallons <br /> of water were removed from each well <br /> ' 26 MONITORING WELL PURGE PROCEDURES <br /> ' On 12 August 1998, a Solinst water level meter was used to measure the depth to ground waiter in <br /> fifteen monitoring wells at the site and nine monitoring wells at the Van Buren site relative to the <br /> tops of the well casings The ground water elevations and hydraulic gradient were determined from <br /> ' these data (Table 2) <br /> Following measurement of ground water depths, in accordance with the revised monitoring schedule <br /> ' established at a 03 April 1998 meeting with the PHS-EHD wells MW-1, MVi'-2, MW-4, MW-13, <br /> MW-19A MW-19B, MW-20A, MW-20B, MW-21A and MW-21B were purged using a two-stage <br /> purge pump The purge pump was decontaminated prior to purging each well by pumping an <br /> Alconox solution followed by pumping tap water At least three well-volumes of water, <br /> approximately ten to twenty gallons, were removed from each purged well Temperature, pH and <br /> conductivity of purged water were measured at regular purge volume intervals using an lCM model 1 <br /> 52200 water analyzer The recorded field data and logs are included in Appendix C All purged water <br /> was stored in 55-gallon DOT-approved drums on-site <br /> ' Adtionced GcoEmironmental,Inc <br />