2006-05-31_REVISION - M1978056 (10)

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s 5~ Varre Gravel Operetlar-Durt~em Pk OIBBIBy. CdOfeflD Page 2 the dewatering operation. The regional site location is depicted on Figure 1. Site conditions are depkited on Figure 2. Site ~xplonstlon and Laboratory Tesdna The bank between the Durham grew operation and Poudre River is approximately 5100 feet in length. The unsaturated bank width varies between 40 feet in the western portion of the study area to in excess of 200 feet ~ the eastern portion of the study area. The river side bank height gerrerelly varies between 12 and 20 feet. The maximum vertical relief on the pit side of the bank is on the order of 50 feet, based in information provided by Anderson Consulting Engineers, Inc. The embankment was inspected on April 12, 2006, and no apparent signs of failure such as tension cracks or raveling were observed. Soil conditions within the bank were evaluated by dolling sbr soB borings with a truck mounted hollow stem auger rig. The depth of the borings varied between 20 and 50 feet bebw grade. Representative soil samples were obtained by advandng a two-inch outside diameter splft barrel sampler ahead of the auger bit Details of each boring bg are presented in Appendix A. Soil descriptions of cores obtained from within the embankment were recorded durirg drilling activities. In general, soil conditions consist of up to Live feet of fill which is underiain by alluvial deposits of well graded sand and gravel. Bedrock, which consists of a dense, dark gray shale (Plane Shale) underiies the sand and gravel deposits. The depth to water within the bank varied between 4 and 22 feet below grade. The boring locations are depicted on Figure 2. Overview of Stabilit~Armlvses Soil samples obtained Trom borings B~, B-4, and B-5 were submitted to CTL Thompson of Fort Collins, Colorado and tested to determine the following properties: -water content;