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I R. • • <br /> Page 2 <br /> CRA MEMORANDUM <br /> the surface. The grout will be allowed to set for a minimum of 48-hours prior to resuming drilling <br /> operations. <br /> This procedure will be repeated for the second conductor casing. <br /> 2.0 WELL DRILLING AND GROUTING PROCEDURES <br /> After the conductor casing grout has set for a minimum of 48 hours,drilling operations will resume for well <br /> installations. The well boring will be drilled with sonic drilling equipment. The well boring will be <br /> approximately 6.25 inches in diameter (Figure 1) and continuously cored. Figure 1 shows the typical well <br /> construction for a 180 ft well. As shown,the total depth is anticipated to be 180 fbg,but the actual well <br /> depth will be dependent on the soil types encountered during drilling. <br /> After reaching total boring depth,a 2 inch nominal diameter Schedule 40 PVC well casing will be installed <br /> within the sonic drilling pipe. The drilling pipe cases the borehole to prevent formation sloughing within <br /> the borehole and to allow proper well construction inside the piping. The well will be screened with <br /> approximately 10 ft of 0.02 inch screen from depths of approximately 170 to 180 fbg. A filter pack will be <br /> placed from the bottom of the well screen up to 2 ft above the top of the well screen,followed by a 2-ft-thick <br /> bentonite seal,and cement grout to grade. <br /> This procedure will be repeated for the 115 ft well. <br />