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Mr. Peter Hays, DRMS <br />September 18, 2015 <br />overflowing. At that point, the pumps at East Branch were turned off. The overall volume <br />of water lost is estimated to be in the 30,000 gallon range. Based on the volume of water <br />witnessed on the tank pad and the evidence of flow paths taken, this would be a <br />reasonable volume. This estimate is also based around all four pumps at East Branch <br />Pumphouse being active and running at a design capacity of 4,000gpm each (16,000gpm <br />collectively) for up to four minutes (estimated time that lapsed between becoming aware <br />and stopping the pumps). The process water tanks include high level overflow drains, <br />which can handle the volume of a slightly more than two pumps running at full capacity. <br />By this logic we took the full output of the pumps for four minutes and divided and <br />subtracted roughly what was believed to have exited through the overflow drains directly <br />back to East Branch Reservoir. <br />After discussing the event with process control employees of Henderson Mill, it was <br />determined that the DCS (digital control system) was temporarily shut down in order to <br />manage some programming issues. This power outage caused the tank level indication <br />to be lost, which in turn provided indication to the East Branch pumps to switch to the on <br />position. Further discussions with the process control engineers showed that there had <br />been a 'jumper' put into the programming at some over the past several years (no detail <br />was available as to why this occurred). The jumper in the programming essentially told <br />the pumps to run, when it was originally designed to stop the pumps if level indication <br />was lost. Process control is currently in the process of removing the jumper to ensure <br />that the programming functions appropriately. That is, if the tank's level indication is lost, <br />the pumps at East Branch Pumphouse will default to the off position. <br />If you have any additional questions or concerns, please feel free to contact me at 720-942-3518 or <br />Miguel Hamarat at 720-942-3255. <br />Sincerely, <br />Tim Haynes <br />Sr. Environmental Engineer <br />Climax Molybdenum Company <br />Henderson Mill <br />CC (via email): <br />B. Romig, Climax <br />M. Hamarat, Climax <br />T. Haynes, Climax <br />S. Deely, Freeport-McMoRan <br />N. Hall, Freeport-McMoRan <br />L. Decker, Gallagher & Kennedy <br />Page 2 <br />