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<br />and HA-4) did not appear to have a weathered zone. The weathered zone is distinguished <br />from the unweathered bedrock by a yellow brown to olive brown color and a very soft to soft <br />hardness. <br /> Top of bedrock was encountered in the borings From 31.5 to 61.0 ft bgs. Estimated depth to <br />unweathered bedrock is 37.3 to 61.9 ft. The Rock Quality Designation (RQD) of the bedrock <br /> ranged From 18 to 100 percent; 22 of the 24 recorded RQD values were greater than 50 <br /> percent. <br /> To provide representative data for excavatability of bedrock material within the designed <br /> excavation depth into bedrock, Table VI summarizes the frequency of SPT test results in the <br /> weathered and unweathered bedrock. In the weathered bedrock, standard penetration test <br /> values range from 10 blows per 6 in. to 50 blows per 0 in. and were typically 50 blows for 5 <br /> to 6 in. In the unweathered bedrock, standard penetration test values ranged from 15 blows <br /> per 6 in. to 50 blows for 1 in. and were typically 50 blows for 4 to 5 in. <br />Unconfined compressive strength tests were performed on intact core samples from below the <br /> design key depth for supplemental information. Samples were selected from several borings <br /> representing a range of lithologies within the mudstone. These selected samples were a <br /> minimum of 4 inches in length and were obtained from core boxes in which the core run had <br />1 been placed and allowed to partially dry. Testing of relative weaker samples that did not <br /> remain intact in the core boxes was not performed. Therefore, the unconfined compressive <br /> strength test information provided does not account for this rock material. Unconfined <br /> <br />' compressive strengths ranged from 190 pounds per square inch (psi) to 3,140 psi for six <br /> selected core samples. <br /> Observations made in the 35`" Avenue gravel pit indicate that the bedrock surface is relatively <br /> smooth. Excavations made into the bedrock for mining operations in one area of this gravel <br /> pit revealed bedrock material similar to that encountered in test borings, and a material <br /> consisting of hard, fresh, sandy to silty limestone, as indicated by moderate to strong <br /> effervescence to hydrochloric acid. This material appears to come from sporadic lenticular <br /> lenses within the bedrock. The extent and thickness of these tenses could not be determined <br /> by observation. However, pieces of these lenses in spoil material suggest that these lenses <br /> -can be 0.5 to 2 ft thick. The unconfined compressive strength from a sample of [his material <br /> was 9,310 psi. This material was not encountered in borings performed directly along the <br /> slurry wall alignment. <br /> 4.06 Groundwater and Surface Water <br />Surface water at the property occurs in the Cache La Poudre River (along the north side of <br />the property}, the two gravel ponds, and the 35'" Avenue Ditch located on the west side of the <br />property. <br />Groundwater was encountered within the alluvium at approximately 10 bgs. Localized <br />perched groundwater (less than 10 ft bgs} can be anticipated in areas where clay lenses exist <br />above the water table. Fluctuations in groundwater level may occur due to variations in <br />10 <br /> <br />