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<br />Kathy Welt and Christine Johnston <br />March 7, 1997 (DRAFT) <br />Page 2 <br />5. Surface waters were diverted from the North Fork according to MCC's decreed water rights. <br />During the short time periods of most years when MCC's direct diversion right was out of <br />priority, North Fork depletions were replaced through the release of MCC's storage rights in <br />reservoirs upstream from the mine. <br />6. Comparisons of North Fork water quality data and whole effluent toxicity (WET) test results <br />upstream and downstream from the mine demonstrated no observed change attributable to <br />MCC's operations. <br />7. MCC's annual mine outflows resulted in insignificant flow increases (< 1 percent) in the North <br />Fork. <br />8. Mine discharges consistently complied with NPDES effluent limitations, primarily because the <br />mine produced relatively uniforni and minimal outflow, with constituents that were readily <br />removed with standazd treatment technologies. <br />This situation changed abruptly and unexpectedly on March 16, 1996, when MCC began to <br />experience inflows from the B East Mains fault. Within a matter of days, groundwater was entering <br />the mine under pressure at a rate of as much as 2,500 gpm (5.6 cfs). The quality of the fault water <br />was roughly comparable to that encountered in the B-Seam elsewhere in the mine, although the <br />temperature of the water was approximately 84°F. The inflow rates far exceeded the capability of <br />MCC: to pump and treat the water. Compounding this situation (throughout 1996), was the presence <br />of a different kind of colloid that did not lend itself to treatment using previously effective methods. <br />1996 Water Management Objectives and Actions <br />MCC mobilized immediately to respond to these problems. After consultation with advisors and <br />regulators, MCC established the following high-priority objectives and actions for groundwater and <br />surface water management: <br />1. Continue to protect the health, safety and welfare of mine workers. <br />2. Enable continued mining to assure that coal production agreements aze met. <br />3. Comply with all relevant environmental permits, to the maximum extent feasible. Provide early <br />notification of particulaz problems, such as emergency dischazges to the North Fork. <br />4. Provide regular verbal and written updates to the relevant regulators, primarily the Colorado <br />Division of Minerals and Geology (CDMG) and the Colorado Water Quality Control Division <br />(CWQCD). Seek their input and recommendations and invite them to visit the mine for first- <br />handevaluations. <br />5. Undertake additional mine development in the eastern portion of the mine with caution, in the <br />event that additional fault inflows aze encountered (particularly where the B East Mains fault <br />projects through the Box Canyon Mains). <br />6. Manage dischazges to the North Fork in accordance with the terms and conditions of the <br />applicable NPDES permit, to the maximum extent practicable. This includes maintaining <br />storage capacity in the ponds to handle the ] 0-year, 24-hour storm event. <br />