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Mr. Brown <br />September 25, 2009 <br />Page 2 <br />adjustment resulted in lowering the crest elevation from the fall 2008 level of 8,845.7 feet <br />to a modified spring 2009 elevation of 8,844.5 feet at the lowest point. An alternate <br />method of constructing the deposition berm should be investigated. <br />The primary purpose of the spring survey is to verify compliance with the flood storage <br />space requirement. In accordance with the February 2005 hydrology analysis, a <br />combined total of 3,582 acre-feet of storage space must be available in the tailings <br />impoundment and East Branch Reservoir. Using the elevation-capacity data from Table 1, <br />the storage capacity of the tailing impoundment at 8,844.0 feet (8,844.5 - 0.5' Freeboard) <br />is 9,106 acre-feet. The following table summarizes the actual amount of flood storage <br />capacity available in the system at various dates throughout the summer of 2009. <br />Available Flood Storage <br />Date Capacity (ac-ft) <br />April 1 4,784 <br />May 4 3,988 <br />June 2 3,891 <br />July 1 3,825 <br />August 1 3,834 <br />September 1 4,114 <br />September 24 4,087 <br />Excess Flood Storage <br />Capacity (ac-ft) <br />1,203 <br />386 <br />309 <br />243 <br />252 <br />532 <br />505 <br />As shown in the table above, there was adequate storage space available in the system <br />throughout the 2009 season. It is expected that there will continue to be adequate storage <br />capacity between now and November, when the spigot pass will be completed and the <br />dam crest will effectively be raised. At that time, there is typically a significant excess of <br />storage space which carries through the winter until the snowmelt inflows occur the <br />following spring. <br />The spring survey provides a pond storage capacity at the time of the survey, but this <br />capacity is constantly changing as additional tailings are deposited in the pond. To