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• <br /> <br /> <br />-~ III IIIIIIIIIIIIIIII • <br />999 <br />Doc Date:1211112001 • <br />STATE OF COLORADO <br />MINED LAND RECLAMATION DIVISION <br />Department of Natural Resources <br />7313 Sherman St., Room 215 <br />Denver, CO 80203 <br />303 866-3567 <br />FAX: 303 832-8106 <br />Septemher 13, 1991 <br />Rockcastle Coal Company <br />Mr. Dean Massey <br />Parcel, Mauro, Hultin and Spaanstra <br />1801 California Street, Suite 3600 <br />Denver, Colorado 80202 <br />RE: Grassy Gap Mine - C-81-039 <br />Dear Mr. Massey: <br /> OF' COQ <br /> a~'.9y <br /> ine' ~y~ ° O <br />' <br />fi ~J "'. <br />~I <br />n ~ <br />/ n ~ <br />~~f Roy Romer, <br />~/ 11 Governor <br /> Fretl R. Banta. <br />I <br />V Division Director <br /> 7 <br /> ~ <br /> .I <br />a. <br /> <br />This letter is written to summarize the major outstanding issues pertaining to <br />Pits S/6 <br />reclamation of the Grassy Gap Mine. 'rle have reviewed t ctober 23, 199A~ <br />letter from Susan McCannon to Brent Anderson, the April 2 1991 letter from <br />Catherine Begej to Rockcastle Coal Company, the April 2 1991 letter from <br />Catherine Begej to Rockcastle Coal Company, and the Notice of Violation <br />C-89-034. This summary includes references to these documents. Please <br />contact us if you need copies of any or all of the documents. <br />We are in receipt of engineering submittals from ACZ, the most recent of which <br />is dated February 21, 1991. The Division letter dated April 24, 1991 was an <br />adequacy review of the February 21, 1991 submittal. Please be sure to review <br />the engineering submittals so that previously approved commitments are <br />properly implemented. The pending issues pertaining to the Pits 5 and 6 <br />engineering work are as follows: <br />1.) Please submit the hand-drawn topography maps, derived by ACZ so <br />that we may evaluate the hydrologic design calculations for Pits <br />and 6. The map should be submitted in some type of formal format, <br />and it should be certified as being a reasenabie approximation of <br />existing topography. Amore detailed map is not being required. <br />Hand drawn maps will net be used to assess achievement of <br />? lapproximat2 original contour. <br />2.> The previous submittals proposed permanent retention of all upland <br />diversion ditches at Pits 5 and 6. Retention of upland diversion <br />ditches is not consistent 'with the regulations, and does not <br />constitute a maintenance free reclamation configuration. As such, <br />we request a revised engineering plan for Pits 5 and 6 which plans <br />for the elimination of all upiand diversion ditches. This plan <br />must also include new pit area diversion designs which account for <br />the increased drainage area. We can accept designs based upon the <br />10-year, 24-hour peak flow, rather than the previously specified <br />100-year, 24-hour peak flow. Include riprap designs where needed, <br />based upon a verifiable riprap design method, and which incorporate <br />proper filter blanket designs. Finally, submit a revised Pond 6/6 <br />design which also accounts for the increased drainage area. <br />_~ - ,~- <br />