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r <br />3.2 CM93 -2 <br />Observation well CM -2 was drilled to provide a means of sampling the <br />ground water in the first aquifer adjacent to and downgradient of the Burbank <br />Repository (Figure 1). CM93 -2 was spudded on 4/26/93 and surface casing set <br />5/8/93. The cement plug below the surface casing was drilled out on 5/10/93 <br />and drilling of the borehole was completed on 5/14/93. The well was logged on <br />6/10/93 prior to construction (Figure 3). Due to problems with the integrety of <br />the PVC casing the construction of this well was not completed untill 9/1/93. <br />3.2.1 Well Construction <br />A 12 -inch hole was drilled and eight -inch steel surface casing set from the <br />surface to a depth of 350 feet with 18 inches above ground level. The steel casing <br />was cemented in place using a cement grout containing 5% bentonite. The <br />surface casing was set to the Summerville thereby protecting the underlying <br />aquifer from ground water in the Salt Wash member of the Morrison formation. <br />A 7 7/8 inch hole was then drilled, with air, to a depth of 870 feet (Figure 3). <br />The well was the developed by air jetting and evacuating the water from the well <br />until all cuttings were removed from the well and the water entering from the <br />formation was clean. This was accomplished prior to constructing the well. <br />The well was then constructed (Figure 3) using 120 feet of slotted (0.03), <br />4.5 inch, SDR 17, PVC pipe from 860 feet to 740 feet. An unslotted section of pipe <br />with a with a PVC cap on the bottom was placed from 880 to 860 feet. Unslotted <br />4.5 inch, SDR 17, PVC pipe was placed from a depth of 650 feet to 18 inches <br />above the surface level. A cement plug was then placed between the PVC pipe <br />and surface casing from a depth of 15 feet to just above surface level. A dedicated <br />pump was installed. <br />7 <br />