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Valley Mater Tre€atinent Page 4 Groundwater Monitoring Well Construction Project No. 480.2 March 14, 2000 ' screened interval consists of 0.010 inch, slotted schedule 40 PVC pipe extending from the total depth of 20 feet and upward a distance of 15 feet in all wells. Number three sand was used to form a filter pack about the perforations and ' extending one foot above the screened interval- An annular seal was constructed by installing sufficient bentonite to form a 1-foot thick seal- The ' granular bentonite was hydrated with tap water and allowed to expand for a period of one hour. The remaining annulus was flied with neat cement grout. The wells were secured with a watertight locking cap encased within a traffic safe well box. The following table summarizes the construction details of these three wells. Depth of Depth of Filter Transition Annular Blank Screen >ack Seal Seal 0 - 20' 207 -5 20' –4' 1 T - 3' 3' –0' TD=Total Depth; All numbers are depths below grade. 2.2 Groundwater Monitoring Well Development & Monitoring ' Immediately after each well was set, it was surged by the drilling company using a stainless steel surge block sized to gauge. After the grout was allowed to set, the wells were developed and then sampled in a separate event. 2.2.1 Monitoring Well Development After construction, the wells were allowed to cure for several days and were developed on December 5, 2005 by Del-Tech Geotechnical Services of Oakdale, CA. Each well was opened and the water level allowed to equilibrate. A submersible pump was used to remove well water and residual solids in the well casing and filter pack. Pumping continued until a clear stream of water was produced. Waste water was temporarily stored in DOT drums on the site. 2.2.2 Groundwater Monitoring Well Sampling On December 9, Del-Tech returned to the site to collect suitable groundwater samples from each well. 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 1 water interface detector suspended from a polyethylene measuring tape, calibrated to the nearest 0.01 foot (see groundwater monitoring data sheets in Appendix Q. A careful notation made of the depth to groundwater as measured by the device. An electronically actuated oil 1 water interface detector was lowered into these wells for the purpose of 2937 Veneman Ave.,#B240 Geo-Phase Environmental Inc. Phone (209) 569-0293 Modesto, CA 95356 Fax (209) 569-0293