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i <br /> 4M494217edwks lKc Page 3 <br /> Dual Phase Extraction Pilot Test Report <br /> r�lsl Project No.723.2 <br /> November 5,2004 <br /> r <br /> 2.0 EXTRACTION WELLS <br /> LIT SJCIEHD approved the installation of three groundwater extraction wells in order to perform <br /> P orm <br /> F the dual phase test. <br /> 2.1 Extraction Well Installation <br /> 1 Prior to commencing work,--a soil boring/monitoring well permit was secured and the <br /> SJC/EHD was notified at least 48 hours in advance. The subsurface was cleared of <br /> underground utilities by notifying Underground Service Alert. <br /> On Jul <br /> 'f y 7 2004 V&W Dulling of Isleton, California mobilized to the site to install <br /> extraction wells EW-1, VEW-1 & VEW-2. The borings were drilled using a ten inch outside <br /> diameter continuous flight hollow stem auger to their total depth. The borings were not <br /> logged during drilling due to their proximity to existing on site wells. <br /> The wells were constructed with 4.0-inch diameter schedule 40 PVC. The following table <br /> illustrates the construction details: <br /> G , Well No. DiamJTD Screen Slot Sand Pack Transition Grout Seal <br /> in/ftInterval ftin ft 'Seal ftft <br /> EW-1 4"154.5' 19.5---54.5' 0.020 18-- 55' 15 - 18, 15'-surface <br /> lam' VEW-1 4"/50' 20—50' 0.020 18-- 50' 15 - 18' 15'-surface <br /> VEW-2 4"/50' 1 20—50' 1 0.020 - 1 18— 50' 1 13.5— 18' 13.5'-surface <br /> 1 <br /> A transition seal of bentonite chips was installed above the sand(0) filter pack, hydrated and <br /> allowed to set for thirty minutes. The surface seal was achieved by pouring a neat cement <br /> grout (augmented with <5% bentonite) into the borehole after the auger flights were removed <br /> (a free fall of less than 15 feet). The well was secured with a locking watertight cap encased <br /> n <br /> in a flush mounted traffic rated well box. 1 <br /> t The well construction details are shown on the boring logs included in Appendix B. <br /> r _ <br /> 2.2 Extraction Well Development <br /> Mr. Don Light of Del-Tech Geotechnical Support developed the three new wells on June 24, <br /> 2004. The methods used to develop the wells included surge block, submersible and Waterra <br /> pumps to remove silt and water from the wells. <br /> 1 <br /> t <br />