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Il. Hydrologic Balance- Rule 4.05 <br /> A. Water Quality Standards and Effluent Limitations <br /> With the exception of approved small area exemptions, all discharges from the Roadside Portal <br /> Mines will pass through sediment ponds or treatment facilities designed to ensure that all <br /> discharges meet applicable effluent limits under the operator's Colorado Discharge Permit <br /> System (CDPS) permit, for the Roadside Portal Mines. Water pumped from underground <br /> workings will be clarified by allowing sufficient settling time in underground sumps,abandoned <br /> areas or mine water treatment ponds prior to discharge into the Colorado River. A storm water <br /> permit and spill prevention containment and control plan associated with the CDPS permit also <br /> dictate preventative and mitigation measures for ensuring that all water leaving the mine site <br /> meets applicable effluent limits. <br /> Receiving stream standards for the Lower Colorado River have been set by the Colorado <br /> Department of Health and Environment in their publication "Classification and Numeric <br /> Standards for Lower Colorado River Basin." The Colorado River at this point is within segment <br /> 2 of the Lower Colorado River sub-basin and basin and Coal Creek is within segment 4 of the <br /> Lower Colorado River sub-basin and basin. CDPS permit limitations on discharge, the permit's <br /> discharge standards, and the Division's standards for determining material damage to the <br /> hydrologic balance("Division Procedures for the Assessment of Material Damage with Respect <br /> to Alluvial Valley Floors, the Cumulative Hydrologic Impact Assessment and Subsidence at <br /> Coal Mines")are based, in part, on these standards. The Roadside Portal Mines' standards for <br /> discharge are listed in Table 2.05.6 A of the permit application. The mines' baseline water <br /> quality data is found in Section 2.04.7 of the permit application. <br /> The CDPS permit had in the past included a specified salinity standard of not more than one ton <br /> per day or 350 tons per year of total dissolved solids, whichever is less. The Roadside Mines <br /> salinity discharge exceeds this level, primarily due to mine water discharges. As a result, <br /> Powderhom Coal was required by the Colorado Department of Health and Environment(DOH) <br /> to prepare a report outlining possible approaches to reducing the mines'contributions of salt to <br /> the Colorado River, and associated costs. This report, "Evaluation of Alternatives for <br /> Management of Salt in Mine Water Discharges: Roadside and Cameo Mines; Powderhom Coal <br /> Company; Palisade,Colorado." was completed in February, 1993. Based on the report, DOH <br /> made a determination that salt elimination or reduction would not be economically feasible,and <br /> granted an exemption from salinity standards (3/17/93 letter, Appen. 17-2). DOH had not <br /> revised that determination, and it remained valid, at the time of RN-03 proposed decision <br /> issuance, in February, 2000. <br /> The Division has granted a number of small area exemptions from the use of sediment ponds due <br /> to the limited size of the areas in question and due to the fact that ponds and treatment facilities <br /> are not necessary for the drainage from these sites to meet the effluent limitations of Rule 4.05.2 <br /> and applicable State and Federal water quality standards for receiving streams and also due to <br /> the fact that no mixing of surface drainage from these areas with a discharge from underground <br /> workings will occur. The small areas to be exempted are listed in Volume 3,Appendix 13-3 of <br /> the permit application (4.05.2(3)(b)(i)). <br /> 24 <br />