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Table 1. Existing Structure and Setback Agreements Closest Distance to Structure Owner Mining Gasline Xcel Energy 1800 Larimer St 50-ft Denver,CO 80202 County Road 179 Routt County Road&Bridge 136 6th St#103 350 Steamboat Springs,CO 80487 Power Poles I Yampa Valley Electric Association Inc. 2211 Elk River Rd 250 Steamboat Springs,CO 80487 Note:These structures and setbacks were compiled from aerial photography and operator knowledge. 2. Slope Stability Analysis A slope stability analysis was performed using GALENA Slope Stability Software, assuming the ground conditions described in the CDRMS permit. The mining plan calls for slopes along the edge of the permit area to be mined to 1.25H:1V or shallower, and then backfilled to the final reclaimed condition of 3H:1V. The strength of the in-place sand and gravel will determine the stability of the Active Mining slope. The material used in the slope stability analysis is sand and gravel - mixed grain size for the aggregate. Backfilled material, assumed to be loose sand, will be used to achieve the Final Reclaimed slope. The bedrock beneath mining is assumed to be intact shale. The water table is located at the bottom during mining due to dewatering, and roughly two-thirds of the way up the vertical distance of mining in the Final Reclaimed condition. All material properties can be seen in the GALENA data output attached. The material properties for these slope materials are shown in Table 2 below. Table 2— Material Properties Aggregate Deposit Description sand and gravel,mixed grain size Loose sand,mixed grain size Unit Weight(Ibs/ft3) 110 99 Friction Angle(°) 45 34 Cohesion 0 0 *Material information is from the SME Mining Reference Handbook(2002 Edition).Values used are the lowest of any ranges.' ' Table 2.5; Originally from Hoek and Bray, 1977 Kattenberg Pit Slope Stability 2 U Lewicki&Associates December 2022