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ECOSA <br />As described in Section 5.7.2, the previously approved ECOSA has been redesigned for <br />MLE2. The redesigned ECOSA will be constructed by end dumping in 300 -foot lifts, in a <br />similar fashion to SGOSA described above. The clay borrow area developed as a source <br />of clay for construction of the VLFs will be backfilled as part of the initial lift of the <br />ECOSA development. <br />ECOSA will be located along the southern (north and east - facing) slopes of Grassy <br />Valley with the vast portions of the OSA lying within the volcanic diatreme. After <br />removal of growth medium, the footprint area will be left in a roughened condition to <br />encourage infiltration of water into diatreme system. Outslopes will be graded to <br />approximately 2.5H:1 V with drainage channels established at the back of each bench <br />graded to drain water away from the ECOSA. Approximately six inches of growth <br />medium will be used to cover the graded overburden. The soil may be sampled to <br />determine the need for additional soil amendments. Vegetation will be established <br />according to the procedures presented in Section 12.3. <br />As discussed in greater detail in Appendix 1, Volume II, the neutralizing capability of the <br />overburden to be placed in the ECOSA, along with the neutralization capacity of the rock <br />in the diatreme, is estimated to be adequate to neutralize any potential water quality <br />changes as a result of the overburden placement into ECOSA. <br />The stability of the reclaimed ECOSA was addressed in Section 5.7.2 of this Project <br />Description. This analysis indicates that the reclaimed area will be stable over the long <br />term. <br />The final reclaimed surface of the ECOSA will be graded to conform to the runoff <br />patterns discussed previously in Section 5.7.2. A discussion of diversion/ conveyance <br />channels and detention basins for the final ECOSA configuration also is provided in <br />Section 5.7.2. <br />Surface Mine Backfill Areas <br />Backfilling is anticipated to occur to the ground surface or higher in two mine areas of <br />MLE2: the North Cresson Mine area and the East Cresson Mine area. The backfill <br />information presented in this discussion is based upon information available at the time <br />of submittal of this document. Actual backfilling may vary according to economic and <br />Cripple Creek & Victor Gold Mining Company <br />Cresson Project Mine Life Extension 2 <br />12 -12 <br />