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Mr. Jack Henris <br />July 13, 2016 <br />Page 6 <br />m:\min\tc1\_teller\m-1980-244 cc-v\am-11\m-80-244-am-11maincommentr12016-07-13.docx <br /> <br />DRMS Table 1. Minimum Factors of Safety for Slope Stability Analyses <br />Type of Structure/Consequence <br />of Failure <br />Generalized, Assumed, or Single <br />Test Strength Measurements <br />Strength Measurements <br />Resulting from Multiple Tests(1) <br />Non-Critical Structures (e.g., <br />fences) / No imminent danger to <br />human life, minor environmental <br />impact, and minor repair costs if <br />slope fails <br />1.3 <br />(1.15)(2) <br />1.25 <br />(1.1) (2) <br />Critical Structures (e.g., <br />residences, utilities) / Potential <br />human safety risk, major <br />environmental impact, and <br />major repair costs if slope fails <br />1.5 <br />(1.3) (2) <br />1.3 <br />(1.15) (2) <br />(1) The number of tests required to provide a high degree of confidence in the strength parameters used <br />depends on the variability of the material being tested and the extent of the highwall disturbance. <br />(2) Numbers without parentheses apply for analyses using static conditions and those within <br />parentheses apply to analyses using seismic acceleration conditions <br />21. Page 11-1, Section 11.1 Surface Water. The last sentence declares “This program provides <br />downgradient flows and water quality from major site drainages …”. The Division has no <br />record of having received water flow and quality data from CC&V. Please clarify what <br />agency is provided with this data. <br />22. Figure 11-1, Water Monitoring Locations. The green text used to label the groundwater <br />monitoring locations is nearly impossible to read. Please use a different color text and/or <br />subdue the background to enhance readability. <br />23. Page 12-12, first Paragraph - Chicago Tunnel Portal Area / Underground Mining. The last <br />sentence indicates the “Portal access will be secured”. Please provide more details on portal <br />closure and whether or not bat activity is/will be considered in the closure design. <br />24. Page 12-13, fourth paragraph – VLF re-contour. The second sentence declares “Portions of <br />the benches created during operations will be retained, as appropriate, for geotechnical and <br />erosional stability.” and Drawing F-1 is referenced for final topography. Drawing F-1 <br />indicates slope lengths exceeding 2,000 feet are likely. Such long slopes will be highly <br />susceptible to erosion gullying. The Division is unaware of any stormwater management <br />designs for the VLF closures. As the end of life for the Arequa Gulch VLF is approaching, <br />please commit to finalizing stormwater management designs for the VLFs in order to assure <br />long-term stability. <br />25. Page 13-2, second paragraph – reclamation grading. The last sentence states “reclamation <br />grading, slope reduction, and contouring oftentimes results in a facility encroaching outside <br />its development footprint, resulting in a slightly larger affected area for reclamation”. Please