2017-01-09_REVISION - M1973007SG

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CMC Continental Materials Corporation • Transit Mix Concrete Co. 440 S. LaSalle St. Suite 3100 Chicago IL 60605 It is important to note that the evaluation was done at a max capacity of the proposed Wash Fines Pond which would have a far greater volume of free standing water than would be present during any sort of transition phase between use of the existing Wash Fines Pond and the proposed Wash Fines Pond. Therefore,a worst case condition was used in the evaluation. Slope Stability Analysis and Factor of Safety Calculations When completing the Slope Stability Analysis and Factor of Safety Calculations Brierley Associates analyzed two stability cases.These cases are Long Term Steady State for extended term stability of the embankment at maximum fill elevation and Long Term Pseudo-Static which introduces seismic loading to the long term steady state case.The following table is an excerpt from Appendix B: Brierley Associates Geotechnical Evaluation Memorandum. A detail of how the slope stability analysis was completed is also included in Appendix B. Table 2.Summary of Slope Stability Findings Colorado Division of Loading Condition Reclamation, Mining,and Computed Safety(2016) Factor of Safety Minimum FS Recommendedi I Long Term Steady State 1.5 1.69 Seepage II Pseudo-Static Seismic 1.3 1.45 Loading 1.For critical structures modeled using generalized or assumed strength measurements. Liquefaction Evaluation Brierley Associates also completed a liquefaction evaluation for the proposed Wash Fine Pond embankment.The design report prepared by Brierley Associates details materials to be used for construction of the embankment and recommends using borrow material from the proposed pond footprint.The laboratory results for this material including gradation, liquid and plastic limits and soil classifications were used to determine if liquefaction would be a concern. Brierley Associates determined that"due to the dense nature and clay content of the eolian soils" recommended for the embankment construction, the potential for liquefaction is judged to be low. See Appendix B: Brierley Associates Geotechnical Evaluation Memorandum,for details. Wash Fines Deposition Plan TMCC will deposit wash fines into the prosed Wash Fines Pond via a pipeline that runs from the processing plant on the West side of Academy Blvd to the top of the proposed Wash Fines Pond embankment.The deposition will take place in a minimum of 3 points along the top of the embankment by either systematically moving the discharge pipe to each point for a yet to be determined amount of time or by constructing a piping system with set discharge points.The length of time that each discharge point will be used has yet to be determined and will depend on the flow of the solids into the proposed pond and along the embankment. The intent of this distribution style for the wash fines is to ensure