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TR43, Runoff Control Structures <br />Response to Comments <br />page 2 <br />• The current design would impound water between the two pipes once the lower pipe inlet u buried with sediment, and <br />between the upper and open spillway channel once the upperpipe inlet is buried. A properly slotted nserpipe extended <br />firm the lower discharge pipe up to the open spillway elevation may be sufficient to properly dewater the, structure within <br />24 hours, throughout the life of the structure. Please revise the designs for the runoff control structures <br />and incorporate a slotted riserpipe or alternative design that will drain all storage within 24 <br />hours throughout the life of the structure. <br />Further, please amend the permit text in Tab 20 page 11, to include a statement that these <br />runoffcontrol structures are not intended to impound water, and wi11 be constructed and <br />maintained to drain all storage within 24 hours. <br />Response: A slotted riser has been added to each discharge pipe in the design per the DRMS request. See <br />Figure 20-2, Typical Runoff Control Structure. <br />Attached is information regarding the potential additions to the typical runoff control structure design. If <br />there are any comments or questions, please contact me at (970)276-5217 or (970) 846-3648. <br />Sincerely, A <br />Roy Karo <br />• Reclamation Manager <br />enclosure(s) <br />cc: Carl Johnston (OSMRE) <br />John Husband (BLM) <br />Sandy Brown (DRMS-Denver) <br />U <br />Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81639 <br />Telephone (970) 276-5219 9 FAX (970) 276-5222