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and the location of the event. At no time did any portion of this event <br />leave, or come close to, the Henderson property boundary. <br />(c) The Operator contact person for this upset is: <br />Tim Haynes, Environmental Engineer <br />19302 County Road 3, Parshall, CO 804568 <br />phone: 303 -569 -3221 ext. 2284 <br />fax: 970 - 725 -0038 <br />(d) Samples were not necessary to evaluate the situation and corrective action <br />(e) A 10 -year maintenance project to the process control system contributed <br />to a lack of logics communication between the tank level indicator and the <br />pumps which fill the tank, which ultimately caused the overtopping to <br />occur. More specifically, when power was taken down at the UPS <br />(Uninterruptible Power Supply), the power was also terminated to the <br />level indicator at the mill process water tanks. Because of this, the local <br />programmable logic controller (PLC) at East Branch Pump House sent a <br />"zero" signal to the pumps. From a logics perspective, the local PLC <br />understood the tanks to be empty and was trying to fill them by turning on <br />all pumps. Henderson's process control department is currently <br />developing an SOP for testing PLC communications and other telemetry <br />prior to maintenance to ensure this issue does not occur again. <br />If you have any additional questions or concerns regarding this upset, please feel free to <br />contact me at 303 -569 -3221 ext. 2284 <br />Sincerely, <br />Tim Haynes <br />Environmental Engineer <br />Henderson Mill <br />Cc: Bryce Romig, Climax Molybdenum Co. <br />Miguel Hamarat, Climax Molybdenum Co. <br />Jerry Roose, Freeport McMoRan <br />Lee Decker, Gallagher & Kennedy <br />