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<br />999
<br />DIVISION OF MINERALS AND GEOLOGY
<br />Department ul Natural Resources
<br />I l l? Sherman SL, Room ! I S
<br />Denver, Colorado 80?U7
<br />Phanr. 13071 866-35hi
<br />FA%.17011 8}!-A 10h
<br />March 13, {998
<br />Richard Mills
<br />Twentmile Coal Company
<br />29515 Routt County Road No. 27
<br />Oak Creek, CO 80467
<br />STATE OF COLORADO
<br />RE: Foidel Creek Mine, C-82-056, Review of PR-04 Responses
<br />Dear Mr. Mills:
<br />~~~~~
<br />l7EPAttTNtENT OF
<br />NATURAL
<br />RESOURCES
<br />Ray Romer
<br />Gwernur
<br />lames s. w~hnead
<br />Ecec W rve Director
<br />ntich~el B. Long
<br />Division Due~lur
<br />The Division has reviewed the remaining responses to Division of Minerals and Geology's adequacy letter
<br />dated August 18, 1997. The remaining items were numbered I, 3, 4, 5, 6, 8, 9, 10, 11, 12, 16, 17, I8, 20,
<br />22 through 26, 32, 35, 37, 38.a), and 41. Additional information or revision is needed for concerns
<br />numbered 3, 4, 9, 17, 22, 32, 35, and 41. Twenrymile Coal Company's responses received on March 9,
<br />1998 adequately addressed the Division's questions with the exception of items 36, 44 f) and g), 46, 47,
<br />and 67. Items 36, 47 and 67 entail submittal of revised maps. The following questions still need further
<br />discussion or clarification.
<br />The information presented on page 2.04-19 discussing faulting and ground water under the
<br />heading EMD AND NORTHERN MPvING DISTRICT should be moved to page 2.04-16 under
<br />the heading EMD AND NORTHERN MINING DISTRICT and before the heading Interpretation
<br />of Overburden Geochemical Data on page 2.04-16.1. Also, a period should be inserted following
<br />the last word on the current page 2.04-16 "...presented for PR-03 is used for this revision as
<br />well(.)"
<br />4. The geochemical sample location CH-82-74C could not be located on Map 12, Geochemical
<br />Sample Locations. Please correct and resubmit the appropriate number of copies of this map.
<br />9. TCC response to this issue is in part adequate, however, requires some explanation and comment
<br />by DMG. Figure 6r and 6s of the existing permit do present baseline water level information for
<br />the Wadge seam overburden and the Twenrymile sandstone in the NMD. DMG believes that
<br />sufficient ground water quality information exists in Twenrymile Park to characterize that baseline
<br />conditions. DMG also understands that TCC is establishing water monitoring well clusters in
<br />section 7 and section 3, TAN, R86W. These well locations should be included in the water
<br />monitoring plan for the NMD in Exhibit 14, referenced by name. When these wells are developed
<br />and stabilized, a minor revision should be submitted to incorporate initial data ,including water
<br />level and quality, into tl7e permit and update or modify Figures 6r and 6s, if necessary.
<br />17. DMG understands the concept of til7e-grained material sealing a subsidel7ce crack. However, in
<br />practice, this phenomenon has no[ been observed i17 the field and DMG does not believe, at this
<br />time, that [his type of sealing took place when Flow was interrupted along Foidel Creek in August
<br />of 1996. As was stated in the original adequacy question, "The Division observed n large crock
<br />trcrversirrg the s[remrr chnrrne! bo[[om on Sep[ember 23. 1996. nearly one mon[h after the period
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