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07 March 2002 AGE-NC Project No 99-0645 Page 5 of 9 ' 3 4 MONITORING WELL INSTALLATION AND DEVELOPMENT A total of three ground water monitoring wells were installed at the site (Figure 2) Following ' drilling and sampling of soil borings B1 through B3 [MW-1 through MW-3],the soil borings were completed as ground water monitoring wells Each ground monitoring well was completed with 20 feet of well screen section The wells were constructed using two 2-inch diameter,schedule 40 PVC 1 casings and have the following designs and material Monitoring wells were constructed with 0 02-Inch slotted screen installed from depths of 80 to 100 feet bsg and with blank casing extending to the surface A filter pack was Installed using#3 Lonestar sand from 78 to 100 feet bsg Bentonite chips were used to make a two-foot transition seal above the ' sand pack The remaining annular space was backfilled to within six Inches of surface grade with portland cement A traffic-rated well box (8-Inch diameter) was installed over each well in accordance with San Joaquin County regulations Monitoring well design specifications are depicted in Appendix B A summary of monitoring well screen depth Intervals are presented in Appendix B Following well installation, the wells were developed in order to Increase water flow Into the well 10 and to minimize the amount of fine-grained sediment drawn into the well during pumping or bailing r3 5 GROUND WATER MONITORING ACTWITIES On 02 November 2001,groundwater monitoring activities were performed at the site Groundwater monitoring activities Included the measurement of ground water levels and collection of ground water samples for the three site-related monitoring wells (MW-1 through MW-3) rThe water level In each monitoring well was measured relative to the tops of the well casings using a Solinst water level meter After water levels were measured, a dedicated,disposable plastic bailer was used to purge each well Five gallons(a minimum of three well volumes)ofwater were removed from the wells Temperature,pH and conductivity of the purged water were measured at one-gallon Intervals using a Hydac water analyzer during purging,and the values had generally stabilized by the end of the purging process(Appendix B) Purged water was stored on-site in 55-gallon,Department of Transportation-approved drums Ground water depth, flow direction, and gradient findings are presented in Section 4 2 36 COLLECTION OF GROUND WATER SAMPLES • Prior to collection of ground water samples,the depth to ground water was measured in each purged Advanced GeoEnvironmental,Inc r