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West Elk Mine <br />were constructed to dewater it. As shown in Exhibit 43 and on Map 54, a 6-inch PVC pipe <br />collects the water and drains it into culvert C 1-6A. MCC has designed and constructed several <br />other french drains around the mine site, as approved by the CDMG, to improve stability. These <br />french drains are shown on Map 54. Sediment traps were constructed below the breaker <br />building to pre-treat (i.e., settle) wash-down water prior to flowing down to pond MB-2R. <br />The locations of these sediment traps are shown on Map 54. MCC also utilizes sediment traps <br />above the inlets to ponds MB-3 and MB-4. <br />General Requirements for Sedimentation Control Facilities <br />All storm drainage/sediment control ponds have been designed in accordance with the <br />requirements of CMLRB Regulations for Coal Mining. In addition, all inspection, construction <br />and maintenance procedures conform to the requirements of these regulations. Flow meters have <br />been installed on all mine water intakes and discharges to measure flows. <br />Sedimentation ponds MB-1, MB-2R, MB-3, MB-4, and MB-5 have gated dewatering systems <br />located above the sediment level. Refer to the designs in Exhibit 43, 48 and Exhibit 66. The <br />dewatering system for SG-1 is shown in Exhibit 66. <br />Sedimentation Pond Operation <br />The following discussions describe significant features associated with and the operations of <br />each of the sedimentation ponds located at the West Elk Mine. MCC usually collects a pre- <br />discharge sample from the ponds to determine if the discharge will be in compliance with <br />MCC's NPDES permit, prior to opening the gate to discharge the pond. The pre-discharge <br />sample is analyzed for total suspended solids, as that is the parameter of concern to MCC. <br />MB-1 <br />Sediment pond MB-1 is atwo-celled pond designed to accept mine water and storm water <br />runoff. However, the majority of the mine water is now discharged through Lone Pine Gulch. <br />Currently, MB-1 handles very little, if any, mine water. The water enters the south cell of the <br />pond. There are four pipes in the dike that separate the two cells to transfer water from the <br />south cell to the north cell if further treatment is necessary prior to discharge. The primary <br />spillway is located in the north cell. The primary spillway is gated to better control discharges <br />from the pond and to assure the discharge will be in compliance with MCC's NPDES permit. <br />The emergency spillway is an open-channel, rock-lined spillway. MB-1 is lined with a HDPE <br />liner that was installed in early 1998. The pond has been designed to hold three years of <br />sediment. Other than the increased amount of sediment that resulted from the large mine <br />water inflow events in 1997, MCC's experience has been that the pond does not have to be <br />cleaned of sediment that often. MB-1 was last cleaned during the fourth quarter of 1997. <br />MB-1 is sized to contain the 100-year, 24-hour storm event, and/or MCC's water right for this <br />pond. Piping is in place to allow water from MB-1 to be pumped to FW-1 for mine water use. <br />MB-2R <br />2.05-32 Revised June 2005 PRIO; Rev. January 2006; Rev. March 2006; Rev. Apri! 2006 PRIO, May 2006 PR10; Rev. January 2009 MR-350 <br />