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2002 -2- 003-2203 - Revision of the solution management routing within the water balance model to provide solution routing from the PSSAs as per the revised operating plan. Solution routing within the water balance model was modified to include the following: • Route any outflow from the Phase I PSSA to the Phase II PSSA; • Route any outflow from the Phase IV PSSA to the Phase II PSSA; and • Route any outflow from the Phase II PSSA to the External Storage Pond. - Increasing the storage capacity in the Phase I PSSA by allowing solution storage up to the PSSA crest (elevation 9365 feet) as this facility gravity drains to the Phase II PSSA. - In preparation of Amendment No. 8 water balance, the storage capacity in the Phase II PSSA was set at a maximum solution elevation of 9305 feet. However, the Amendment No. 8 text inadvertently references a maximum elevation of 9307 feet. In the revised model, the Phase II PSSA elevation remains unchanged from the Amendment No 8 model at a maximum elevation 9305 feet. - Revision of the Phase IV PSSA storage capacity to account for the following: • Changes in the grading plan; • Updating the PSSA dry porosity to be consistent with the method applied to the Phase I and Phase II PSSAs in Amendment No. 8. This method accounts for variable ore height within the PSSA. In Amendment No 8, the ore porosity for the Phase IV PSSA was set at 0.28, which is the lowest measured dry porosity value for minus one-half-inch ore under the maximum ore height. However, the ore height within the PSSA vanes between zero to 590 feet, therefore the dry porosity within the PSSA will vary with ore height. For the most recent water balance model, Golder has calculated a weighted ore dry porosity average value of 0.305. The dry porosity was weighted based on the ore height distribution within the PSSA consistent with dry porosity calculations in Amendment No. 8 for Phase I and Phase II PSSAs. • The maximum solution storage elevation for the Phase IV PSSA was set at 9624. If outflow occurs from the Phase IV PSSA, the solution is routed to the Phase II PSSA via gravity. z:wo~zzo>\woo~exawraenwsozwoszzo3.oooo.aJbzo.ooC Golder Associates