Laserfiche WebLink
When any environmental problem or concem is identified (by our Environmental Staff, other employees, <br />agency personnel, neighboring property owners, or the general public), it is our standard practice to: <br />• Immediately investigate the problem or concem <br />• Initiate appropriate action to prevent or mitigate immediate impacts <br />• Develop and implement any additional mitigation or corrective measures in a timely manner <br />• Take appropriate steps to assure that the problem or concem will not occur again (either at the <br />location of the original occurrence or any other location) <br />Relative to Parts 1.3, and 4: <br />Key considerations relative to the unanticipated production mine water (treated water piped through <br />underground system for use on longwall and continuous miners for cooling and dust control) discharge <br />and the subsequent exceedance of design capacity for the SAE drainage structures at the NW Mains <br />Ventilation Fan faciliryinclude: <br />1) TCC had no reason to anticipate that production mine water discharge would occur through the <br />accumulator pipe at the NW Mains Ventilation Shaft <br />2) The designed and approved drainage and sediment control features for the NW Mains Ventilation <br />Fan facility are suitable for the site, meet all applicable regulatory requirements, and have <br />functioned effectively under normal storm runoff conditions to effectively control drainage and <br />sediment from the site <br />3) The quality of water used in the production mine water system and which was accidentally <br />discharged at the NW Mains Ventilation Fan site meets applicable discharge effluent standards <br />4) On discovery of the accidental production mine water discharge, TCC took immediate directed <br />action to stop the discharge and prevent any further or future discharge from the site or other sites <br />5) Inspection of downgradient areas confirmed that the production mine water discharge did not <br />result in any direct discharge to Fish Creek <br />The following provide additional details relative to these keyconsiderations: <br />1) The production mine water discharge and subsequent exceedance of design capacity for the NW <br />Mains Ventilation Fan Facility SAE resulted from unanticipated and unforeseen upset conditions <br />in the underground mine water handling system The circumstances resulting in the unanticipated <br />production mine water discharge were determined as soon as reasonably possible after the <br />inspection and descnbed in an a-mail (dated 5/05/05, copy attached for reference) from Jerry <br />Nettleton, of TCC, to Byron Walker, of the Colorado Division of Minerals and Geology (CDMG). <br />Following my initial inquiry (as referenced above), I was able to obtain additional information on <br />the Roll-Seal failure, that modifies and clarifies information provided in the referenced e-mail The <br />production mine water system is protected by two separate sets of Roll-Seal pressure reducing <br />valves. The fast set of valves is located in the North Main Entries and is set at a relief setting of <br />3S0 psi. The second valve set is located in the Northwest Main Entries and is set to limit <br />maximum system pressure to 475 psi. Under nomral circumstances, the system pressure at the <br />bottom of the Northwest Mains Ventilation Shaft (due to a head differential between this point <br />NOV CV-2005-006 2 b/3/2005 <br />