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20. Page 7-1, Section 7.2.1 Stabilfty Anal <br /> • The factors of safety(FOS) for the SGVLF are stated to be 1.3/1.5 for operation and <br /> reclaimed static conditions, respectively; and 1.0/1.1 for the pseudo-static conditions <br /> during operations and reclamation, respectively. The Division has adopted new FOS <br /> standards for slope stability as shown in DRMS Table 1 (top of p. 6). The stated FOS <br /> for static conditions meets the Division's new criteria(right column applies in most <br /> cases as numerous tests have been performed on the VLF material to establish strength <br /> parameters). It should be noted the Division considers state highways and county roads <br /> to be critical structures.Neither the operational, nor reclamation FOS for pseudo-static <br /> conditions satisfies the new criteria. However, as the SGVLF was approved with <br /> MLE2/AM-10, prior to the Division's adoption of these criteria, we will not require a <br /> change to the design slope. The Division is also aware of an annual geotechnical <br /> assessment/evaluation of mine slopes performed by outside consultants. The Division <br /> requests a commitment from CC&V to provide a copy of the report generated from this <br /> annual slope stability assessment <br /> DRMS Table 1. Minimum Factors of Safety for Slop a Stability Analyses <br /> Type of Structure/Consequence Generalized,Assumed,or Single Strength Measurements <br /> of Failure Test Strength Measurements Resulting from Multiple Tests(') <br /> Non-Critical Structures(e.g., 1.3 1.2S <br /> fences)/No imminent danger to (1.1S)(2) (1.1)(2) <br /> human life,minor environmental <br /> impact,and minor repair costs if <br /> slope fails <br /> Critical Structures(e.g., 1.5 1.3 <br /> residences,utilities)/Potential (1.3)(2) (1.1S)(2) <br /> human safety risk,major <br /> environmental impact,and <br /> major repair costs if slope fails <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 /> RESPONSE: A Geotechnical Slope Recommendations study was included as Appendix <br /> 5 to the Amendment 11 application. Because the general mining activities did not <br /> change as a result of the proposed Amendment 11 activities, a Geotechnical assessment <br /> other than what was provided in Appendix 5, was not included with the application. <br /> Further discussion of FOS is provided in responses to comments No. 31-34 below. An <br /> annual inspection/geotechnical assessment of the VLFs was completed in December <br /> 2015, a copy of which is provided in Attachment 6. CC&V will provide a copy of the <br /> 2016 assessment when it is completed. <br /> 21. Page 11-1, Section 11.1 Surface Water <br /> • The last sentence declares"This program provides downgradient flows and water <br /> quality from major site drainages ...". The Division has no record of having received <br /> water flow and quality data from CC&V. Please clarify what agency is provided with <br /> this data. <br /> RESPONSE. The Water Quality Control Division (WQCD), of the Colorado <br /> Department of Public Health and Environment receives water quality and flow data for <br /> the outfalls permitted under the Colorado Discharge Permit System (CDPS)program <br /> pursuant to the Colorado Clean Water Act. A list of CDPS permits is provided in <br /> Exhibit M. The other surface water locations are monitored on a regular basis and data <br /> is maintained by CC&V in its Environmental Data Management System (EDMS). Data <br /> Page 10 of 30 <br />