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S Z <br />.SMITH WILLIAMS CONSULTANTS, INC. <br />• <br />6.2.2 System Outflow Evaluation <br />System outflow components include evaporative losses, the difference in ore moisture between <br />as-delivered moisture content and field capacity (moisture lock-up), and solution delivered to the <br />process plant. Evaporative losses were modeled using historic climatological data collected at <br />CC&V. Monthly evaporative losses were estimated based on the areas under leach and inactive <br />areas. This differs from the previous Amendment water balance models, which simply assumed <br />a yearly average of 2 percent of the applied solution. Monthly evaporative losses based on <br />evaporation data and active/inactive areas is more realistic as evaporation rates will vary monthly <br />and vary for active and inactive leaching areas. This same approach was also used for the <br />approximate 8-year post-mining leaching operations period. <br />The field capacity moisture content of the ore was modeled at 7.5 percent of dry weight, based <br />on data provided by CC&V. Data pertaining to the ore field capacity are presented in <br />Appendix B. The moisture content of the ore during active leaching will exceed the static field <br />capacity. The leaching ore moisture content was modeled to vary between 9.5 and 10 percent by <br />dry weight. <br />• An advantage of the dynamic water balance model is that it simulates solution flow from the <br />PSSAs to the process plant. This provides an opportunity for the operation to actively manage <br />the solution levels and volumes within the PSSAs, to maintain sufficient capacity for <br />contingency inflows. For example, by pumping more solution from the PSSAs than is applied in _ <br />leach solution, the level of the PSSA can be dropped, thereby providing more storage volume. <br />Using this methodology, the mine can effectively manage the solution levels in all of the PSSAs. <br />6:2.3 Contingency Inflows <br />As in previous Amendments, the water balance model includes contingency inflows. These <br />include 12 hours of draindown and the 100-year/24-hour design storm event. The draindown <br />volume was calculated based on application rate for each PSSA during operations. Inflow from <br />the 100-year/24-hour design storm event was calculated as the storm depth (3.5 inches) applied <br />to-the lined area for each PSSA. The contingency inflows are delayed reporting to the PSSAs <br />based on the average ore depth. <br />6.3 Discussion of Results <br />The results from the dynamic; probabilistic water balance model are summarized in Figures 5 <br />through 9; which present predicted PSSA and ESP volumes as a function of time. The curves <br />i <br />S:\PROJECTS\1125 CC&V PHASE 5 VLF\H2 - DESIGMAREQUA VLF\VLF PHASE 5 FINAL REPORT V2.DOC 44 <br />