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diversion channel as part of the final reclamation for the TDA. Extreme storm events <br />(greater than the 100-year, 24-hour event) would flow from the South Diversion and <br />report to the reclaimed TDA impoundment surface as previously contemplated. The <br />reclaimed TDA surface will be graded to route water to a spillway channel <br />constructed in the northwest abutment of the tailings embankment. <br />This change in TDA reclamation design is more protective than the original <br />reclamation design because runoff from most storm events will be routed around the <br />TDA rather than over the reclaimed TDA surface. Furthermore, during extreme <br />storm events up to and including the PMP, high, peak inflows are attenuated on the <br />tailings impoundment and released to downstream areas at greatly reduced flow rates. <br />This more evenly distributed outflow will result in reduced downstream erosion under <br />extreme rainfall-runoff conditions. <br />The amended reclamation design is described in detail in Appendix C. Detailed <br />construction drawings will be prepared prior to construction and upon completion of <br />construction, an as-built report documenting the TDA reclamation construction will <br />be submitted to DBMS. This report will consist of record drawings, a summary of <br />construction quality control and quality assurance testing, and photographs of <br />construction progress. <br />Peak stormwater runoff reporting to the TDA surface during the PMP is <br />approximately 7,900 cubic feet per second (cfs). A concrete weir will be used to <br />control the outflow from the TDA and will result in a peak spillway flow of 430 cfs <br />during the PMP event. A maximum of 440 acre feet of water would be temporarily <br />stored on the TDA surface during the PMP, with a resulting maximum pool elevation <br />of 8610.3 feet. Thus, a minimum freeboard of 8 to 10 feet will be maintained <br />between the maximum pool level and the embankment crest (elevation 8620 ft +/-). <br />Storage of extreme-event stormwater within the TDA will be temporary, with less <br />then 0.5 feet of water remaining on the TDA surface after three days. <br />Battle Mountain Resources, Inc. 16 <br />P:\Projmu\212-Ne nt(SariLWs)\SanLuis\Pe tAmendment- WeA Pit Mam®ement\V5 Report &PDFs\TaR\Petmit>m nd=nI v5e.doo December 2007