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cap to allow drainage of the groundwater from the cap should the water level <br /> fall below the elevation of the lowest perforation in the casing. <br /> The slot size opening of the screen will be based on the size of the filter or <br /> gravel pack material. The grain size range of the gravel pack material will be <br /> based on the texture of the formation material opposite the screened section. <br /> For these two wells with unconsolidated material present in the screen <br /> interval, the grain size distribution of the formation material will be <br /> determined by geologist's examination or sieve analysis, if needed. The <br /> gravel pack and slot size would then be selected based upon the results. <br /> The annulus around the well screen will be filled with a sand filter material <br /> appropriate to the formation lithology as described above. The filter pack will <br /> be placed as a slurry, using a tremie tube. It will be placed so as to rise 18 to <br /> 24 inches above the top of the screen. Above the filter pack, a three to five <br /> foot thick bentonite seal will be placed. Because of the difficulty of using <br /> bentonite pellets in deep wells with significant standing water, a bentonite <br /> slurry will be pumped down the annulus through a tremie tube. The annulus <br /> above the seal will be filled with a cement/bentonite grout containing 6.5 <br /> gallons of water and four pounds of powdered bentonite for each 96-pound <br /> bag of cement. The constituents will be combined in a grout mixer and <br /> pumped down the annulus through a tremie tube. Care will be taken to stage <br /> the pouring of the neat cement to fill the annulus so as not to damage the PVC <br /> ZAPROP-PR7\19WI524-pWelivbleVp1-1524.I.d= <br /> 11 <br />