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Based on my review of leachate pipe system behavior under the <br />equivalent loads posed by the 800 feet high heap I do not see any <br />concerns related to the pipe capacities under these conditions. There will <br />not be an increased fluid head on the liner system caused by pipe <br />deformation resulting from these high heap heights. <br />c. Heap Leach Material Behavior <br />Pregnant solution is stored in the pore space of the heap at the PSSA's for <br />the different phases. In order to provide adequate storage it is essential <br />that the pore space in the ore does not reduce significantly when it is <br />compressed to the overlying loads. A series of compression and <br />percolation tests are reported in Appendix B.4 of the AMEC report. These <br />tests were carried out to an equivalent height of 565 feet. The percolation <br />through the material was at least ten times that applied in the field and <br />there were very small changes in the overall particle size distribution. <br />Appendix B.3 of the AMEC report provides the results of load-permeability <br />tests on Cresson ore. Figure 7 of this Appendix shows the typical void <br />ratio - log of normal stress plot for the results. Extrapolating this graph <br />indicates that the void ratio at an equivalent load of 800 feet will not <br />decrease significantly. <br />The liner puncturing tests described above did not find significant particle <br />break down until the load exceeded an equivalent height of 1,020 feet. <br />The Phase 5 expansion will result in a heap height of about 700 feet <br />above the Phase 4 PSSA (based on a review of the isopach map and PSSA <br />locations with John Lupo on July 18, 2008). Based on the compression <br />tests and the liner puncture test results it is not expected that there will <br />be significant particle crushing or significant decrease in void ratio under <br />these loads. <br />It is concluded that the heap height of 800 feet will not adversely affect <br />the capacity of the PSSA's. <br />3. Dynamic vs. Static Water Balance <br />In previous permit applications the water balance calculations were done using <br />deterministic methods based on monthly intervals. In these models there are no <br />dynamic interactions between various parts of the model. For example, it is <br />assumed that on a monthly basis all the leachate that is applied to any part of <br />the heap will report to the PSSA during that month, similarly for precipitation. In <br />the case of very high heaps such as present and future conditions at the Cresson <br />project, this assumption does not hold and recent advances in systems models <br />5