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iii iiiiiiiiiiiiiiii <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Depanmenl of Nal ural Resources <br />131 3 Sherman $l.. Ruom 215 <br />Denver, Colorado 80203 <br />Phone' 0071 866-3567 <br />FA%. 031872-B1 6 <br />~une 1 1996 <br />Mr. Murari P. Shrestha, P.E. <br />Western Fuels-Utah <br />405 Urban Street <br />Suite 305 <br />Lakewood, Colorado 80228 <br />RE: Refuse Area Revegetation Study Final Report <br />Deserado Mine (C-81-018) <br />Dear Mr. Shrestha: <br />~I~~~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Rol Romer <br />Governor <br />dames S Lochhead <br />6ecuil.~e Dlreaor <br />ntichaelB Long <br />Division Dlreaor <br />I have reviewed the above referenced report, which we received <br />January 31, 1996. The report clarified certain issues which were <br />unclear in the draft report, and responded to certain concerns we <br />had identified in a review letter of November 13, 1995, and the <br />enclosure memo dated October 31, 1995. <br />In the cover letter to the final report, you indicate that there <br />has been no problem with salt migration to this date, and in <br />addition state that the study data support WFU's belief "that a 24 <br />inch thick cover will provide equal or better revegetation success <br />compared to a 48 inch thickness." I do not concur with these <br />conclusions, based on the data presented to date. As I indicated <br />in the summary paragraph of the October 31, 1995 memo, the <br />vegetation data were largely inconclusive with respect to the <br />effects of cover soil depth on vegetation success parameters due to <br />the confounding topographic effects and overall poor establishment <br />of seeded vegetation. As a result, I had recommended that any <br />proposal to reduce the required refuse cover depth to less than <br />four feet would need to be supported by additional intensive soil <br />sample data and literature review. My opinion in this matter has <br />not changed after reviewing the final report. <br />Reoulatorv Requirement <br />The general requirement for cover soil replacement on coal mine <br />waste banks is "4 feet of the best available non-toxic and non- <br />combustible material..." However, Rule 4.10.4(5) provides that the <br />"Division may allow less than 4 feet of cover material based on <br />physical and chemical analyses which show that the requirements of <br />4.15 will be met." <br />Relevant Literature <br />The primary concern with regard to the potential inhibitory effects <br />of the coal refuse material on revegetation success is due to <br />