Laserfiche WebLink
_MOUNTAIN COAL <br />COMPANYL.L.C. <br />A Subsidiary of Arch western Resources, LLC <br />West Elk Mine <br />P.O. Box 591 <br />5174 Highway 133 <br />Somerset, CO 81434 <br />(970) 929-5015 <br />Fax (970) 929-5595 <br />"Pond MB-5E was designed so that each pond cell can be operated independently. One cell ofpond MB-5E <br />is generally utilized to handle stormwater runoff while the other cell is closed and left empty and ready to <br />accept stormwater when the other cell has filled or for water storage, if needed. When the open, active pond <br />has filled to near the maximum fill level, the inlet to the empty pond is opened and the full pond inlet is <br />closed. The full pond is then discharged as described below. When the sediment level reaches the cleanout <br />level in one cell, the runoffflows are closed to that cell and opened to the other pond cell. The pond cell that <br />is full ofsediment can then be completely drained and sufficiently dried for cleaning. <br />The pond has been designed to store a three-year sediment volume. A 54-inch riser pipe serves as the upper, <br />maximum level (primary) outfall in each cell of pond MB-5E, and contains two 12-inch gated drainpipes at <br />different elevations in the riser pipe. To better manage the ponds for CDPS permit compliance, MCC <br />typically does not allow the pond to fill and spill into the primary outfall riser pipe. Instead, after sufficient <br />settling time, the top drainpipe (mid pool level) is typically utilized first to discharge from the middle level <br />of the pond, avoiding potential floating or settled debris. The bottom drain can then be opened to further <br />lower the pond level to better empty the pond for cleaning. The emergency spillway is an open-channel, <br />rock lined spillway. MB-5E is sized to contain the 100 year, 24-hour storm event, and/or MCC's water right <br />for this pond. " <br />5. The footnote of Table 42E (attached) has been corrected to state "*2-year storage in 1 cell of 2-cell pond. <br />Total storage of 1.10 ac-ft (4 years) combined." <br />6. A note has been added to the primary outfall structure cross-section B on drawing CPP-L007 (attached) that, <br />"appropriate barriers will be added to culverts through the embankment to control piping. <br />7. Cross-section B on drawing CPP-L007 (attached) has been corrected to show 2:1 embankment slopes (see <br />notation on cross-section where EL 6045.0 line ends) as specified in the pond stability analysis completed by <br />Barr Engineering provided yesterday to the CDRMS (also see response #1). <br />8. The revisions to the permit text proposed in TR119 and further revised as above, have been incorporated into <br />the revised permit pages per TR118. See pages 2.05-33 through 2.05137, attached. <br />9. The Division's assistance with preparing the reclamation cost estimate is appreciated. <br />Please don't hesitate to contact me should you have questions. <br />Sincerely, <br />Kathleen G. Welt <br />Environmental Engineer III <br />cc: Doug Nolte -MCC