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similar water quality to that of the regional ground water table exiting the Carlton Tunnel <br />portal. Appendix 1, Volume II provides a complete discussion of the expected <br />performance of the ECOSA construction design. <br />Surface Water Management <br />CC &V has evaluated the final configuration for the redesigned ECOSA and designed a <br />surface water management system to route flows and control sediment transport and <br />erosion during construction through completion of reclamation. This system is discussed <br />in Section 10.0 of this Project Description and Appendix 12, Volume VI. <br />The surface water management system for final configuration of the redesigned ECOSA <br />uses the same criteria as outlined above in subsection 5.7.1 for the SGOSA. Diversion <br />and conveyance structures are designed to route flows from the 100 -year, 24 -hour <br />precipitation event. These flows are directed to detention basins, with the most <br />downgradient structures designed to contain twice the 10 -year, 24 -hour precipitation <br />event. <br />Stability <br />The geotechnical stability of the ECOSA was evaluated in a manner consistent with that <br />of previously approved documents and with the SGOSA discussed above. In summary, <br />this analysis used a peak ground acceleration of 0.08 g for the pseudo- static analysis for <br />the post - closure configuration. Other input parameters remain the same as those used in <br />other analyses and were derived from field examinations, laboratory tests, use of accepted <br />numerical assumptions for certain rock types, and the proposed dimensions of the <br />overburden fill during placement and upon regrading. FOS for the ECOSA were derived <br />for both static and pseudo- static conditions. The stability was analyzed for post - <br />reclamation conditions and the results indicate that the minimum static FOS exceeded 1.5 <br />and the minimum pseudo- static FOS under earthquake loading exceeded 1.3. For <br />additional details on the stability analysis for the ECOSA please refer to Appendix 8, <br />Volume IV. <br />5.7.3 Deposition of Overburden into Mine Areas <br />General <br />Backfilling of certain mine areas continues to be a mine planning feature in MLE2. Mine <br />area backfilling during MLE2 will occur in the Main Cresson Mine area, East Cresson <br />Mine area, and the North Cresson Mine area. Backfilling is shown conceptually on <br />Drawings C -4, C -5, C -6, and F -1. Note that the amount of backfilling which will occur <br />Cripple Creek & Victor Gold Mining Company <br />Cresson Project Mine Life Extension 2 <br />5 -21 <br />