2012-05-11_PERMIT FILE - C1981033 (3)

Home Browse Search

2.05.3(4) Ponds, Impoundments, and Diversions provide sufficient volume for sediment and retained water. Spillways and outlet devices were selected that would handle the design storm events and provide sufficient outflow rates. The pond was designed under the direction of a qualified, registered professional engineer. The purpose of the sedimentation pond is not only to provide a final measure to prevent additional contributions of sediment outside the permit area, but also to provide a means of compliance with all applicable effluent limitations, especially with respect to total suspended solids. The effluent quality is regulated by Rule 4.05.2, and by the National Pollutant Discharge Elimination System ( NPDES) Permit. The NPDES Permit was issued by the State of Colorado, Department of Health under the National Pollutant Discharge Elimination System, established as a result of the Clean Water Act (33 U.S.C. Section 1251, et sec). A copy of the NPDES Permit is presented in Exhibit 4, Permits for Mining. The engineering parameters for the sedimentation pond and diversion ditches are included in Exhibit 11, Drainage and Sediment Control Plan. During November 1997, a slide occurred on the southwest corner of the Bear No. 3 Mine surface facilities. Shortly after the slide occurred, about 10 gallons per minute of water began flowing from the east slide scarp. Initially the Operator believed the water emerging from the slide was mine water discharge. Mountain Coal Company convinced the DMG and the Operator that the water emerging from the slide was not water from Mountain Coal Company's operation. Therefore, the Operator suspects the water is not mine water but spring water. This water may have been present for many years and probably contributed to the degradation of monitoring well AA1. See discussion in Section 2.05.6(3). The water flows through mud and slide debris prior to the point it can be contained in a pipe or pond. The Operator constructed a treatment pond for this water to assure the suspended solids are settled before the water is discharged to the river. The pond is no longer required. The Operator can capture water from the berms shown on drawing 11 -5 and discharge directly to the river and meet discharge permit requirements. The Operator plans to construct a treatment pond bypass ditch as shown on drawing 11 -5. DRMS approval will be obtained before the bypass ditch is constructed. The treatment pond will be reclaimed shortly after the pond bypass ditch is operational. The treatment pond location and details are presented on drawing 11 -4. Design parameters for the pond are presented on page 11 -14. Designs for the bypass ditch are shown beginning on page 11- 15. 2.05-23 04/30/2012