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Wesl Etk Aline <br />which aze all sized for the 100-yeaz, 24-hour storm event. <br />During construction of the West Elk Mine, a spring was located on the site where the substation <br />was to be built. In order to stabilize the substation pad, a french drain system and collection pipe <br />were constructed to dewater it. As shown in Exhibit 43 and on Map 54, a 6-inch PVC pipe collects <br />the water and drains it into Culvert C 1-6A. MCC has designed and constructed several other french <br />drains around the minesite, as approved by the CDMG, to improve stability. These french drains <br />aze shown on Map 54. <br />Sediment traps were constructed below the breaker building to pre-treat (i.e., settle) wash-down <br />water prior to flowing down to pond MB-2R. The location of these sediment traps are shown on <br />Map 54. MCC also utilizes sediment traps above the inlets to ponds MB-3 and MB-4. <br />General Requirements for Sedimentation Control Facilities <br />All storm drainage/sedimentcontrol ponds have been designed in accordance with the requirements <br />of CMLRB Reeulations for Coal Mining. In addition, all inspection, construction and maintenance <br />procedures conform to the requirements of these regulations. Flow meters have been installed on ' <br />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 discussion describes 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 ensure the dischazge will be in compliance with MCC's NPDES permit. <br />The emergency spillway is anopen-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 water <br /> <br />2.05-31 Revised Jan 1996 R,V03; Revised Nw. 1996 PRO:: Revised Jan 199i TR79; Revised lul. 1997 TR8?: Revised Jun. 1999 TR90 <br />