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M <br />Alluvium Unit Qa2 at the existing borrow pit, see Table 1. Gravel in a loamy sand to <br />sand matrix that is similar to River Alluvium Unit Qal at the existing borrow pit was <br />encountered in Exploratory Pits P2 and P3. Regional information from the National <br />Resources Conservation Service (2013) indicates that coarse rocks (greater than the No. <br />10 sieve) make up around 60 percent of the high -level Blue River alluvium in the project <br />area. For River Alluvium Unit Qal, representative values for the coarse rocks should be <br />about 55 percent gravel and 5 percent cobbles. For River Alluvium Unit Qa2 <br />representative values for the coarse rocks should be about 25 percent gravel, 25 percent <br />cobbles and 10 percent boulders. The maximum boulder dimension observed in the seven <br />exploratory pits was 4 feet. Free - flowing ground water.was not encountered in the seven <br />exploratory pits but the gravel deposit was very moist near the shale contact and seasonal <br />Perched ground water should be expected near shale at the new borrow site. <br />LABORATORY TESTING <br />Laboratory testing being performed on samples obtained from the exploratory pits consist <br />of gradation analyses, plasticity index and LA abrasion. Gradation analysis was <br />performed on disturbed bulk samples of the coarse granular soils (minus 5 to 8 -inch <br />fraction) taken from the pits and LA abrasion was performed on two samples of the <br />gravel. The gradation test results are presented on Figures 6 through 8 and summarized in <br />Table 2. The LA abrasion tests performed by WesTest are attached and indicate <br />relatively low loss values in the acceptable range for CDOT aggregate base course. <br />LIMITATIONS <br />This study was conducted according to generally accepted geotechnical engineering <br />principles and practices in this area, at this time. We make no warranty either express or <br />implied. The information presented in this report is based on our field observations, <br />published regional geologic information, the exploratory pits located as shown on Figures <br />2 and 3, laboratory testing and our experience with gravel deposits. Our findings include <br />interpolation and extrapolation of subsurface conditions between the exploratory pits and <br />variation in subsurface condition between the pits may not become evident until <br />Job No. 114 342A C-v ec 1 <br />