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STABILITY EXHIBIT <br />General <br />A slope stability analysis was performed for the Bromley Lakes Property located in Adams County, <br />Colorado. The purpose of this analysis was to investigate appropriate mining highwall setback distances <br />from man-made structures. Below we present a brief background and the results of our findings. <br />Background <br />The site is located southwest of the city limits of Brighton, Colorado. Brighton Road is immediately <br />east of the site. The South Platte River flows approximately 1,000 west 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). <br />Analysis <br />Our stability analysis involved generating a computer model of limit equilibrium analysis using the <br />Slope/W computer program. <br />The stratigraphy, encountered during the October 2008 site investigation was used to develop the model. <br />Sandy clay layers are typically encountered in the alluvial sand and gravel stratum. These layers are <br />colloquially known as "mud lenses." No significant mud lenses were encountered during the <br />investigation of this site. Therefore, mud lenses were not incorporated in the slope stability model. <br />Three cross-sections were used to evaluate the setback distances during mining. These were: a cross- <br />section near Brighton Road, a cross-section near the Spier property, and a cross-section near the <br />McCanne Ditch. The soil profile analyzed consisted of 6 to 12 feet of overburden clays overlying <br />approximately 18 to 28 feet of sand and gravel on top of claystone bedrock. <br />One of the test holes (TH-16) indicated that a deeper mining depth might be possible than these three <br />cross-sections indicate. However, this one isolated test hole was over 350 feet from any structures near <br />the site; therefore, this one test hole was excluded from the model geometry. <br />DRMS Analysis, Highwall Setback from Significant Permanent Man-made Structures <br />The Division of Reclamation Mining and Safety (DRMS) requires that gravel pit highwalls within 200 <br />feet of significant manmade permanent structures (such as utilities) be investigated for slope stability. <br />Furthermore, the DRMS requires that the gravel mine highwalls be modeled as vertical unless it can be <br />demonstrated that the slope angle of the highwall will be controlled during mining. The DRMS requires <br />that the analysis be performed using the DRMS strength parameters for sites where laboratory testing is <br />absent. These were the strengths utilized in our analysis. The parameters are provided below on Table <br />1: <br />Bromley Lakes <br />DRMS 112 Permit <br />Page SE1 of SE2 <br />