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' Bank of Stockton - Cutter Lumber Site Page 6 Groundwater Monitoring Well Construction ' Project No 102 2 . April 24, 1998 ' within a traffic safe well box The following table summarizes the construction details of these seven wells ' Well Construction Details Well No TD Screen Interval Seal Slot Size ' MW-6 45' 45' - 20' 20'- 18' 0 020" MW-7 45' 45' - 20' 20'- 18' 0 020" MW-8A 90' 90' - 80' 76 - 72' 0010" MW-813 50' 50' - 25' 25'- 23' 0 020" ' MW-9 45' 45' - 20' 20'- 18' 1 0 020" MW-10 45' 45' - 20' 20'- 18' 0 020" MW-11 45' 45' - 20' 20'- 18' 0 020" ' After the monitoring wells were constructed, the vertical and lateral position of each well was determined by a licensed surveyor The elevations were tied to ' sea level based on a nearby City of Stockton bench mark ' 2.2 Groundwater Monitoring Well Development & Monitoring 2.2.1 Monitoring Well Development After construction, the wells were developed on March 12, 1998 by Del-Tech Geotechnical Services of Oakdale, CA Each well was opened and the water level allowed to equilibrate As each well was opened, and prior to taking the depth to groundwater measurement, a PID organic vapor meter was used to screen for VOC's in the head space of the well The depth to groundwater was ' measured by lowering an electronically actuated air / water interface detector suspended from a polyethylene measuring tape calibrated to the nearest 0 01 foot (see groundwater monitoring data sheets in Appendix C) A careful notation ' made of the depth to groundwater as measured by the device Special effort was made to determine if free phase gasoline might be present in MW-6 or MW-7 An electronically actuated oil / water interface detector was lowered into these ' wells for this purpose No measurable free product was detected ' Each well was developed by inserting a Grundfuss submersible pump into the well and lowing it to bottom Well water was pumped into 55 gallon DOT approved polyethylene drums, properly labeled, and temporarily stored on-site ' The rate of well purging was monitored, and each well was purged of at least three casing volumes or until the groundwater parameters (temperature, conductivity, and pH) had stabilized indicating that water representative of ' actual aquifer conditions was entering the well Groundwater parameter stabilization was characterized by three successive readings within 10 percent 2937 Veneman Ave ,#B240 Geo-Phase Environmental Inc Phone (209) 569-0293 Modesto, CA 95356 Fax (209) 569-0293 1