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iii »~iii~r~iiii iii <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Drpdnment ui N.nural Krsnur[es <br />I { I) ]hcrmdn SL. Ronm 215 <br />Denver, QduroJo iJU'Ol <br />Fhnnc; 130}I lipb-5567 <br />FA\' iSU'S1 H 52-+41110 <br />April 16, 1999 <br />James A. Kiger <br />Sr. Environmental Engineer <br />Colowyo Coal Company L.P. <br />~?3l State Highway 13 <br />Meeker. CO 81641 <br />RE: Minor Revision 51, Permit C-81-019, Adequacy Review <br />Dear Mr. Kiger: <br />olvlsloN of <br />MINERALS <br />GEOLOGY <br />RECLAMATION <br />nINING•SAfETY <br />Bill Owens <br />Cnvemor <br />Grc;; E bValcne, <br />Execwrve Din•uor <br />nichael B. Long <br />Divu~on Dueonr <br />Receipt of Minor Revision (MR) Number 51 for the addition of 3 additional stock ponds on <br />reclaimed azeas of the Colowyo Coal Mine initiated an in-depth review of the applicability of a <br />number of rules, and how these rules have been interpreted and applied. One finding of this <br />review is that the stock ponds, at this time, are "impoundments' as defined by Rule 1.04(64). <br />Thus the adequacy of your submission was determined upon fulfilling the requirements of the <br />rules as relate to impoundments. <br />Item 1. This item requires no action by you for this revision. As impoundments, the proposed <br />stock ponds are regulated structures. Regulated structures are, in tttrn, appropriate to technical <br />revisions. The first six ponds were permitted under Technical Revision (TR) Number 38. The <br />second three were inadvertently permitted under MR-45 and these three under MR-5I. Future <br />submissions, however, need to be processed as technical revisions. <br />Item 2. Rule 4.05.6(3)(e)(ii) requires that emergency spillway design flows be non-erosive. <br />Please demonstrate that the grassed-lined emergency spillways will handle design flow velocities <br />without erosion. (Please also provide such demonstrations for the 3 ponds permitted under MR- <br />45.) <br />Item 3. Please demonstrate that the spillways of the ponds can accommodate the 25-year, 24- <br />hour precipitation event [Rule 4.05.6(5)(b)]. (Please also provide such demonstrations for the 3 <br />ponds permitted under MR-45.) <br />Item 4. Rule 4.05.9(l)(e) engages the maximum design requirements of U.S. Soil Conservation <br />Service Public Standard 378, "Ponds", Colorado, January 1989 (TG 378). [n this regard, a stated <br />purpose of the ponds is for watering of live stock. Please provide in your detailed design criteria <br />a portion of the inside slopes (ramp) at slopes not exceeding four horizontal to one vertical. <br />(Such general design criteria would apply to all of the stock ponds.) <br />