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STABILITY EXHIBIT <br />General <br />A slope stability analysis was performed for the Parsons Mine located in Weld County, Colorado. The <br />purpose of this analysis was to investigate appropriate mining-highwall setback distances from man <br />made structures. Below we present a brief background and the results of our findings. <br />Background <br />The site is located east of the city limits of Windsor, Colorado. Weld County Road (WCR) 64'/2 forms <br />the northern boundary. WCR 25 bisects the site. The Cache La Poudre River flows through and <br />adjacent to the southern portion of the site. <br />The proposed gravel mine is to be mined with a highwall slope inclination of approximately 0.5:1 <br />(horizontal to vertical). After mining, a final reclamation slope of 4:1 or flatter will be constructed using <br />on-site overburden soils. <br />Analysis <br />Our stability analysis involved generating a computer model of limit equilibrium analysis using the <br />Slope/W computer program. In addition to the mining highwall, long-term stability of the reclaimed <br />slope was also evaluated. <br />The stratigraphy, encountered during the March 2002 to April 2007, site investigations was used to <br />develop the model. Sandy clay layers are typically encountered in the alluvial sand and gravel stratum. <br />These layers are colloquially known as "mud lenses." No significant mud lenses were encountered <br />during the investigation of this site. Therefore, mud lenses were not incorporated in the slope stability <br />model. <br />A worst case cross section was used to evaluate the set back distances for each phase during mining. <br />The worst case of these was used for the long term reclaimed slope. A description of each cross section <br />is presented below. <br />The soil information used for our analysis came from six test pits and 45 borings. The various <br />exploration locations used in our analysis are shown on Figure 1 and the information gained the soil <br />explorations is summarized on Table 1 below. Copies of the exploration logs are attached. <br />Table 1: Pnrcnnc Ming- Rnrinnc <br /> Depth (feet below ground surface) of Unit Encountered Estimated Depth to <br />Boring Name <br />Silt and Clay Sand and <br />Gravel <br />Bedrock groundwater during <br />drilling(feet) <br />MW-1 0to9 9to14 14 9 <br />MW-2 0 to 14 14 to 28 28 14 <br />MW-3 0 to 4 4 to 29 29 14 <br />MW-4 0 to 4 4 to 11 11 4 <br />MW-5 0 to 14 14 to 28 28 9 <br />MW-6 0 to 9 9 to 24 24 9 <br />MW-7 0 to 9 and 11 to 14 9 to 11 14 9 <br />MW-8 0 to 5 5 to 17 17 9 <br />MW-9 0 to 4 4 to 14 14 9