2012-05-18_HYDROLOGY - C1981033 - Laserfiche WebLink

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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division Rationale - Page 2, Permit No. aPERMIT NUMBER» pH. The Division's standard practice is to apply pH effluent limitations directly, without a mixing analysis, unless requested or determined appropriate on a case by case basis. In this case the Division has determined that it would be appropriate to apply a mixing analysis for pH for this discharge, based on available dilution in the receiving water and the fact that the pH effluent limitations based on ELGs of 6.0 s.u. (minimum) and 9.0 s.u. (maximum) do not apply to inactive mining operations where reclamation has been completed. The ambient pH condition in the North Fork of the Gunnison from Muddy Creek to Paonia is 8.1 to 8.6. The dilution ratio of the North Fork to the permitted discharge flow is over 500:1 (acute low flow of 31 cfs, permitted discharge of 0.06 cfs). This ongoing discharge would easily meet the applicable pH effluent limit after application of a mixing analysis. In this case the Division is unable to issue a renewal permit to Bear Coal Company since the company has dissolved. Instead the Division is documenting the appropriateness of an alternate effluent limit for pH in this permit termination action. The Division also considered temperature in this termination decision. This is based on the fact that since the last permit renewal, revised water quality standards have been adopted state -wide and assigned to specific stream segments in the state, including the segment to which this discharge occurs, and the fact that the seep /spring discharge is elevated for temperature. The Division determined that it was appropriate to rely on DRMS's determination that the cause of temperature in the discharge is not likely to be human - caused (a mine fire) and that it is more likely the result of geothermal heating (DRMS 2012). On that basis no temperature effluent limitation would be applied to this discharge consistent with the provisions at Regulation 31(14)(b). There are no instances of instream exceedances of any of the parameters covered in the permit. Based on Bear Coal no longer being a legal entity, that all activity at the site has ceased, and that in accordance with the above mentioned policies that the discharge without treatment can meet the limitations that are or would be allowable in the permit, the Division is noticing termination of this discharge permit. This termination action is based on information currently available to the Division, and in particular key facts regarding the water quality of the seep /spring discharge and the inactive status of the mining operation. Any new information, future exploration, mining, influence from adjacent operations, or other information that becomes available in the future could substantiate a different permit determination. Andrew Neuhart April 12, 2012 References: Interoffice Memorandum, Hillside Seep at Bear No.3 Mine Division of Reclamation Mining and Safety, March 7, 2012. Water Quality Permits Policy 1, Permit Inactivation Policy Where a Discharge Remains Water Quality Control Division, 1986. Water Quality Permits Policy 5, Permit Policy for Mining Activities Water Quality Control Division, June 24, 1987.