GENERAL53961

• Permit No: M1984014
• IBM Index Class Name: General Documents
• Doc Date: 8/10/2006
• Doc Name: Supplemental Geology report
• From: Cotter Corporation
• To: DRMS
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

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cotter
July 17, 2006
Russ Means
Colorado Division of Minerals and Geology
Grand Junction Field Office
101 S. Third St, Room 301
Grand Junction, Colorado 81501
RECEIVED
AUG 1 p 2006
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RE: Pennit No. M-1984-014, JD-8 Mine, DMO Appeal; Supplemental Geology Report
Mr. Means:
A good general description of the geology of the area of the JD-8 Mine was included in
the report submitted to DMG October 19, 2005 prepared by Geoscience Services entitled
"Evaluation of Potential Contaminant Migration for Uranium Mining Operations at the
JD-8 Mine". That, and subsequent documents reported on the hydrogeologic properties
of the rock units present at the surface and underlying the mine site, including hydraulic
conductivity and sorption potentials.
The following report, map, and cross-section are provided to give the Division more
detail on the geologic setting of the JD-8 Mine waste rock dump. This is a portion of the
supplemental information Cotter Corporation is submitting to support Cotter's appeal of
the Division's determination that the JD-8 Mine is a Designated Mining Operation.
The structural setting of the mine site was also previously described as located on the
southwest flank of the Paradox Valley collapsed salt anticline. Here, there are several
steep faults which have dropped blocks of various width downward toward the Valley.
The trace of the southwestern most fault underlies the extreme southern edge of the JD-8
dump. This fault can be traced for several miles both southeast and northwest from here.
The block north of this fault is about 800 wide while the present width of the dump is
about 150 feet. To the southeast, the first down-dropped block bounded by this fault
widens to over a mile wide. Northwestward, however the area consists of numerous
small blocks dissected by faults of much smaller displacement. All of the JD-8 Mine
workings are under Monogram Mesa, which is not faulted. (This was shown
schematically in cross-sections submitted with the earlier reports.)
The waste rock dump sits on mudstone of the Brushy Basin member of the Morrison
formation, except for the part south of the fault which sits on lower beds of the Salt Wash
member of the Morrison. This is shown in detail on cross-section A-A'. A separate
report being submitted by Geoscience Services will cover the hydraulic properties of the
Coj~.( r oratyo~n -West Slope Operations Telephone [phone]
P.di9- 21 tJpDD Road, Nucla, CO 81424 USA - 1 - Fax [phone]