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iiii~niiiiiimiii <br />September 16, 1994 <br />Ms. Christine Johnston <br />Colorado Division of Minerals and Geology <br />1313 Sherman, Roam 215 rr1~1 r~ <br />Denver, CC+ ~~ rrr`'-'~'`~r~J <br />Subject: Minor Revision 134, West Elk Mine, Mountain Coal Compa~~et~'t ~~-80.007 <br />Dear Ms. Johnston, <br />f)IVi51U11 Vi nmioi aia c4 UcUNgy <br />Ms. Kathlcen Welt of Mountain Coal Company haz asked me to respond to the throe outstanding hydrology <br />questions on the adequacy review letter dated September 14, 1994. These questions concern the substation <br />small area exemption, question A, and the revised SAE demoostratioos for the fan area, questions B and G <br />/Responses are discussed in the order in which they are asked <br />i 1/ A. A revised Small Area Exemption (SAE) demonstration is provided (see attached) that does not requve <br />' ~ ~ the use of silt fences or straw bale dikes using the porous rock check dam routine, per your request <br />~Ul~Ska MCC will employ either straw bales or silt fences along the lower perimeter of the pad until the pad is <br />gravelled and the topsoil pile seeded and mulched. <br />i t t C " 1~.1~The channels will be constructed az earthen channels. Enclosures 6, 8 and 9 have been revised to show <br />~ J, "null" structures at the channel and culvert nodes, and the Non-Pond Input-Output print-out bas been <br />~ n, S '~~: <br />a ~ `excluded unless there are vegetative filters employed in the run. <br />,~~~t~ <br />f , '~ ~ G 'Ile designs found in the watershed run (Enclosure 6) refieMed lower discharges (<0.1 cfs) than those <br />.. ~ _; . reported in the channel description output. The SEDCAD+ Ditch Utility does not accept discharges <br />~ Tower than 0.1 cfs. Enclosure 6 was modified to respond to question B, and thus this issue is moot <br />~,,- <br />Thank-you for your prompt review of this material. Please call if you have any questions. <br />Sincerely, <br />~~f III.Q C~~ CJ ~- <br />Catherine W. Begej <br />Supervising Hydrologist, Greystane <br />ce. Kathleen Welt, MCC <br />Attachments <br />5990 Greenwood Plaza Blvd. Suite 250 Englewood, CO 80111 <br />(303) 850-0930 Fax (303) 721-9298 <br />