Laserfiche WebLink
Slope Stability Analysis <br /> Pit 124—Varra 112 Permit Application <br /> Weld County,Colorado <br /> Page 3 <br /> Discussion <br /> As the stratigraphy varied significantly across the study area several model runs were made <br /> to simulate the conditions encountered during drilling. A review of the model results <br /> indicate that a safety factor of slightly greater than 1.3 is achieved for a uniform slope of <br /> 1.25H:1V at a bank height of 40 feet — this safety factor is contingent on the lower sand <br /> and gravel deposits having a friction angle of 45.1 degrees. This scenario is depicted on <br /> Plate 1 in Attachment B. In other stratigraphic sequences safety factors of slightly less than <br /> 1.3 are predicted. Model results indicate that using a lower bank slope (20 feet) of 2H:1V <br /> will result in safety factors of greater than 1.4 using any stratigraphic sequence. These <br /> scenarios are depicted on Plates 2-4. Using the different wet unit weights reported in Table <br /> 1, resulted in safety factor differences of less than 2 percent. Figure 2 presents the area <br /> that should be considered for the 20 foot modified cut slopes. If any significant <br /> modifications to proposed pit wall slopes occur this analysis may not be representative of <br /> site conditions and additional simulations arerecommended. <br /> Comments <br /> The discussions and recommendations in this report represent our professional opinions. Our <br /> conclusions, opinions and recommendations are based from information available at this time <br /> and we do not guarantee that undiscovered conditions will not become evident in the future. <br /> AWES' report was prepared in accordance with currently accepted engineering practices at <br /> this time and location and no other warranties, representations or certifications are implied or <br /> intended. <br /> This report was prepared by AWES, LLC. <br /> Date: December 23, 2019 <br /> Joby L. Adams, P.G. <br /> Principal/Hydrogeologist <br />