Laserfiche WebLink
• The computer software Terramodel® was utilized to calculate volumes for the new refuse pile. <br />Ten-amodel is afull-featured civil engineering design software package developed by Trimble <br />Navigation, Limited®. <br />Field Investigation <br />In September 2002, four test borings were drilled in the vicinity of the existing refuse pile to <br />obtain bedrock depth information and to obtain soil samples for laboratory testing. The borings <br />indicated a depth to bedrock of 20 feet was typical in this azea. The colluvium soils were <br />chazacterized as sandy clay to clayey sand with significant grave] that had very little moisture. <br />Samples were taken of the colluvial soils for laboratory testing. <br />In November 2002, the proposed refuse pile was mapped to delineate bedrock outcrops, extent of <br />colluvium, and locations of springs or landslides that might affect the stability of the new refuse <br />pile. The plan view of the geologic map is shown on Figure 1 (Existing Site Plan and Geologic <br />Map). <br />This mapping effort indicated the azea is geologically stable consisting of colluvium overlying <br />sandstone. Sandstone outcrops were mapped at both the lower and upper ends of the new refuse <br />pile. There was a debris flow at the upper elevation of the proposed refuse pile starting at <br />elevation 6,220 MSL which was a result of a landslide further up the ravine. -This material was <br />• approximately 8 to 12 feet thick composed mainly of sand, clay, and boulders and appeazed to be <br />stable. <br />To further determine the thickness of the colluvium in the general refitse pile a geophysical study <br />was performed (a conventional drill rig could not access this azea). This study performed by <br />1JMS in April 2003, delineated the thickness of the colluvium along the centerline, at the <br />proposed sedimentation basin centerline and at a section along the proposed light use road. The <br />report by L1MS is presented in Appendix A. <br />Refuse Pile Slope Stability Analysis <br />Environmental Strategies utilized the softwaze program SLOPE/W and method of slices to <br />evaluate the stability of the refuse fill slopes. SLOPE/W, developed by GEO-SLOPE, is a <br />softwaze package that uses limit equilibrium theory to compute the factor of safety and earth and <br />rock slopes. Slope stability was evaluated utilizing both wedge and circulaz failure scenarios. <br />The rock surface in the region was observed to be irregulaz, so the rock-colluvium interface was <br />presumed to be similaz. <br />The Colorado Division of Minerals and Geology (CDMG) Rule 4.09.1 {7) requires a factor of <br />safety of 1.5 for static conditions for any proposed refuse pile. A seismic factor of safety of 1.1 <br />is also generally recommended for engineered embankments. The horizontal acceleration <br />assumed is 0.08g for Zone 1. <br />• <br />2 <br />