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-,r~ <br />l.:../IJ~ ju`d <br />COIiPo HYTroH <br />• avoid damage to the PVC casing caused by the <br />weight or pressure of the cement slurry column, <br />• provide approximately 50 feet of reliable <br />cement seal above the cement basket and <br />the test interval, and <br />• assure displacement of the borehole fluids <br />by the cement slurry. <br />Cement slurries Caere generally mixed at a ratio of <br />about seven gallons of water to each 94 pound bag of cement <br />(7:1). We11 GF-2 cement caas mixed at about 13:1, because of <br />the locaer bursting strength (180 pound/inz) of the plastic tremie <br />pipe used on that well. General Portland Type 2 cement was used. <br />In most cases, 20 sacks of cement Caere slowly added to 132 gal- <br />lons of water in a 220 gallon water tank. The slurry was cir- <br />•~ culated and mixed using the drilling rig's mud pump. <br />The resulting 200 to 220 gallons of 7:1 cement slurry <br />were then pumped down the tremie pipe into the borehole. After <br />pumping the cement slurry, the tremie pipe was removed from the <br />borehole and the cement slurry was allowed to set for 24 hours. <br />3.2.5 Well Bailing and i1e11head Construction <br />Piezometer wells which were drilled using drilling <br />mud were bailed after allowing time for the cement to set up. <br />Bailing caas done by a small well service rig. Bailing caas car- i <br />ried out until clear water was produced from the well. j <br />A cement slurry was poured between the 10-inch steel <br />surface casing and the 4-inch PVC well casing. The cemented <br />~ intervals were typically from land surface to a depth of five feet <br />• ~ <br />3-8 <br />