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The Pittsburg & Midway Coal Mining Co,
<br />A Chevron Company
<br />6400 South Fddler's Green Circle, Englewood, CO 80111-0991
<br />Mail Adtlrees: P.O. Box &519,Engle+,ood, CO 8015SbS19 ~ FAI((303) 9364204 ~ Phone (303) 93P3600 q ~r'Kll/ED
<br />JAN ~ 0 1.9,9,5
<br />Divrs,~ ,
<br />January 18, 1995 °i r~;merais a Georo9Y
<br />Permit C-80-001
<br />Midterm Review
<br />Technical Revision 30
<br />CERTIFIED MAIL RECEIPT P 919 328 476
<br />Mr. Ken[ Gorham
<br />Colorado Division of Minerals and Geology
<br />1313 Sherman Street, Room 215
<br />Denver, Colorado 80203
<br />Dear Mr. Gorham:
<br />Pursuant to our discussion on January 10, 1995, regarding geohydrologic information for the
<br />Edna Mine area, enclosed are two reports providing additional characterization of the stratigraphy
<br />and groundwater hydrology in the area.
<br />The first report, entitled "Engineering Feasibility Report - Hydrogeologic Relationships & Mine
<br />Inflow Assessment -West Ridge Project Edna Mine, Oak Creek, Colorado', D'Appolonia, 1977,
<br />provides information on the internaauonships in the hydrologic regime of [he overburden, Wadge
<br />Coal seam, underburden and the Trout Creek alluvium on the east side of Trout Creek. The
<br />second report, entitled "Phase II -Trout Creek Project", Watec, 1978, describes the same inter-
<br />relationships among the geology on the west side of Trout Creek in relation to a proposed Wadge
<br />Coal seam underground mine.
<br />Additional geologic characterization is provided in "Geology and Mineral Fuels of Parts of Routt
<br />and Moffat Counties, Colorado", Bass, N.W., et al, Geological Survey Bulletin 1027-D, USGS,
<br />1955. Drillhole logs DH-1, DH-2, and DH-47 shown on Plate 22, and DH-31 (Plate 23) from
<br />this publication provide the most insight about the stratigraphic column from the middle coal group
<br />(Lennox, Wadge and Wolf Creek seams) down to the Trout Creek Sandstone. Further
<br />geohydrologic information is provided in "Geohydrologic Evaluation of the Upper Part of the
<br />Mesaverde Group, Northwestern Colorado", Water-Resources Investigations Report 90-4020,
<br />USGS, 1990 (pp 16-19, 52, 54, 56, 64, 74-75, 80, 82-83, 97-98, 112-114). Finally, the
<br />Division's Proposed Decision documents regarding the Edna Mine (1981, pp 9-10 and 19; 1987,
<br />pp 6, 12, 16, 20, 26-33; 1992, pp 7-8, 24-26) provide information on the geohydrology of the
<br />area and potential impacts.
<br />You indicated during the discussion held in early January that the Division had infotmation
<br />pertaining to impacts on the Trout Creek Sandstone due to mining activities associated with the
<br />Wadge Coal seam. To enhance our understanding of the concerns raised by the Division regarding
<br />the potential for impacts to the Trout Creek Sandstone from mining activities at the Edna Mine, we
<br />request a copy of the information that initiated the Division's concerns.
<br />
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