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Rationale for Recommendation to Approve 11 <br /> September 29, 2016 <br /> reference. All records, including blast statistics and blast monitoring, will be kept on file for a minimum <br /> of three years. <br /> Exhibit D includes a mitigation plan, describing how the operation will respond to complaints from <br /> surrounding structure and groundwater well owners regarding potential impacts from blasting activities. <br /> The mitigation plan details the measures to be implemented and their associated timeframes. <br /> The Division has determined that the blasting plan submitted in Exhibit D, and the geotechnical <br /> assessment submitted in Exhibit 6.5, demonstrate that off-site areas will not be adversely affected by <br /> blasting, as required by Rule 6.5(4). <br /> 2. Concerns regarding geotechnical stability of the site, and the geotechnical stability assessment <br /> provided in the application, specifically as follows: <br /> • Rock catch berms, illustrated on Figure G-2, will catch only 99% of rock fall and are thereby <br /> inadequate to protect Little Turkey Creek Road <br /> • Pit slope movement monitoring should be conducted <br /> • Instrumented holes should be installed behind the highwalls and monitored for pore water <br /> pressure, a concern for highwall stability <br /> • The stability assessment does not satisfy the requirements of Rule 6.S(1) <br /> (N.Reed) <br /> As described in Exhibit S, and observed by Division staff during site inspections, the portion of Little <br /> Turkey Creek Road located within and/or nearby the affected lands is a two-track dirt road traversing the <br /> floor of a narrow canyon, and is exposed to seasonal flooding and natural rock fall. The robust stormwater <br /> control structures proposed in Exhibit G demonstrate how the mining activity will not exacerbate the <br /> flooding hazard for Little Turkey Creek Road or to downstream and off-site areas, in accordance with the <br /> requirements of Rule 6.5(1) and C.R.S. 34-32.5-116(4)(h), (i) and 0). <br /> Given the presence of steep cliffs composed of jointed, fractured, and faulted bedrock, the application <br /> acknowledges the occurrence of natural rock fall. Rock fall is a clear and present geologic hazard at this <br /> site. The application proposes to mitigate the hazard by reclaiming all highwalls to stable configurations, <br /> as demonstrated by geotechnical and stability analyses with appropriate factors of safety incorporated into <br /> the analysis. As noted by the Objector, the application demonstrates 99% of rock fall will be retained on <br /> the reclaimed highwall bench. According to the blasting plan provided in Exhibit D, Little Turkey Creek <br /> Road will be secured during blasting to safeguard the public. Blasting operations will be monitored to <br /> ensure that damage to structures will not occur. The road,from each gate to the operation,will be inspected <br /> following each blast. Should a rock fall onto Little Turkey Creek Road, regardless of the cause, the <br /> Operator will immediately clear the rocks off the road. The application demonstrates how the mining and <br /> reclamation activities will not exacerbate the geologic hazard at the site, thereby demonstrating <br /> compliance with the applicable requirements of Rule 6.5(1). <br /> The application includes engineering stability analyses for not only reclaimed slopes, but also for <br /> highwalls, waste piles, embankments, backfill areas, and stockpiles of topsoil and fines as they occur <br /> during the active mining phases, as required by Rule 6.5(2). Throughout the mining and reclamation <br /> process pit slopes will be monitored for movement with a robotic prism monitoring system, which will <br /> of:coo,\ <br /> 131� Sl'ernial C` Rco 215, Dei` ' , (0v':tf' r 3P3. ,.35671=302,M31C))6 �C�, 5�90t <br /> �{ O <br /> H: -kei'.CtU £i, i.7:7 R'; 1""1:, `_'?' C,;_.+„- D a fit._'.'ron., D`re!:to t <br /> �til 8 7 6� <br />