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Former Nelson Ready Mix Page 5 <br /> Groundwater Monitoring Well Construction <br />' GPE Project No 5111 <br /> March 30, 2006 <br />' screened interval consists of 0 010 inch, slotted schedule 40 PVC pipe extending <br /> from the total depth of 20 feet and upward a distance of 15 feet in all wells <br /> Number three sand was used to form a filter pack about the perforations and <br />' extending one foot above the screened interval An annular seal was constructed <br /> by installing sufficient bentonite to form a 1-foot thick seal The granular <br /> bentonite was hydrated with tap water and allowed to expand for a period of one <br />' hour The remaining annulus was filled with neat cement grout The wells were <br /> secured with a watertight locking cap encased within a traffic safe well box The <br /> following table summarizes the construction details of these three wells <br /> Depth of Depth of Filter Transition Annular <br />' Blank Screen pack Seal Seal <br /> 0 - 20' 20'—5' 1 20'—4' 4' - 3' 3'—0' <br /> TD=Total Depth,All numbers are depths below grade <br />' 2.2 Groundwater Monitoring Well Development & Monitoring <br /> Immediately after each well was set, it was surged by the drilling company <br /> using a stainless steel surge block sized to gauge After the grout was allowed to <br /> set, the wells were developed and then sampled in a separate event <br />� . 2.2.1 Monitoring Well Development <br /> After construction, the wells were allowed to cure and were developed and <br /> sampled on February 17, 2006 by Del-Tech Geotechnical Services of Oakdale, <br /> CA Each well was opened and the water level allowed to equilibrate A <br /> submersible pump was used to remove well water and residual solids in the well <br /> casing and filter pack Pumping continued until a clear stream of water was <br /> produced Waste water was temporarily stored in DOT drums on the site <br /> 2 2.2 Groundwater Monitoring and Well Sampling <br /> As each well was opened, and prior to taking the depth to groundwater <br /> measurement, a PID organic vapor meter was used to screen for VOC's in the <br /> head space of the well The depth to groundwater was measured by lowering an <br /> electronically actuated air / water interface detector suspended from a <br /> polyethylene measuring tape calibrated to the nearest 0 01 foot (see <br /> groundwater monitoring data sheets in Appendix C) A careful notation made of <br /> the depth to groundwater as measured by the device An electronically actuated <br /> oil I water interface detector was lowered into these wells for the purpose of <br /> determining the presence of free-phase diesel fuel No measurable free product <br /> was detected <br /> The wells were sampled using a Wattera pump with new, dedicated, Teflon <br /> tubing for each well Well water was pumped into 55-gallon DOT approved <br /> 2937 Veneman Ave ,#B240 Geo-Phase Environmental Inc Phone (209) 569-0293 <br /> Modesto, CA 95356 Fax (209) 569-0293 <br />