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Mr. Lazuk and Mr. Valentine <br /> June 13, 2018 <br /> Page 2 <br /> Modification Plan 3 <br /> This plan is shown on Figure 1 b and consists of extending the 5 Dam Seepwater Return Pipeline <br /> up the groin of 5 Dam to the existing cyclone overflow pipeline bench. At this point, the seepwater <br /> pipeline would be connected to the cyclone overflow pipeline and the combined flow would be <br /> conveyed to Mayflower TSF. <br /> Modification Plan 4 <br /> This plan is shown on Figure 1c and consists of extending the 5 Dam Seepwater Return Pipeline <br /> further up the groin to the existing Mayflower TDL bench. The seepwater flow would then be <br /> conveyed along the TDL bench to the discharge location of the existing PDWTP Mayflower Return <br /> Pipeline, where it flows down to Mayflower TSF. <br /> It is possible that some of these modifications plans will not be implemented. For example, the <br /> decision may be made to progress from Plan 2 to Plan 4 for whatever reason. Also, the 5 Dam <br /> Seepwater Pumps will be modified if necessary to accommodate the pipeline modification plans <br /> described above. <br /> With respect to schedule, the critical factor is the elevation of 5 Dam, which is ultimately <br /> dependent upon mine production rate. However, the timing of the transition to Modification Plan <br /> 2 is primarily dependent upon the performance of the existing pipeline across the TSF. When <br /> this pipeline becomes unusable, then Modification Plan 2 will be initiated. Using the current long- <br /> range mine production forecast, it is estimated that the transition to Modification Plan 3 would be <br /> required in approximately 2022 or 2023. The transition to Modification Plan 4 is estimated to be <br /> needed in approximately 2028 or 2029. <br /> R-\1000\1051\1051.27\EPP\2018 Revision\180620_Memo_5-Dam-Seepwater-Plans.docx <br />