PERMFILE41370

• Permit No: C1981028
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: APPENDIX F GEOLOGY
• Media Type: D
• Archive: No

1-1
I •
1.0 INTRODUCTION
I 1.1 PURP05E AND SCOPE
On Nay 21, 1981 the Cooca Energy Company (Coors) requested that
r Ertec Rocky Mountain, Inc. (Ertec) perform an earth resistivity survey
along seven survey lines at the Keansburg Hine site. The purpose of the
investigation was to determine the location and if possible, the depth of
the paleo-channel of Ennis Draw and any other paleo-channels found during
the survey.
During the investigation Ertec completed 41,200 feet of resistivity
profiling and performed 49 vertical electric soundings. We reviewed
information supplied by Coors including geophysical loge of exploration
holes, aerial infra-red and color photographs, the Environmental Document
for the Reensburg Mine site (1979), and a report detailing the construc-
tion and completion of the Laramie-Fox Hills water wells which were
constructed at the site.
~• l.2 BACKGROUND GEOLOGY
The Reensburg Mine site is located in the Colorado Piedmont Section
of the Great Plains Province. Coors ie going to mine the No. 7 coal seam
which is the uppermost coal seam in the Laramie Formation. The No. 7
seam is overlain by gray-black shales and weathered iron-rich clays.
Several thin iron cemented sandstones interfinger with the ahalea. The
ahalea are overlain by the weathered clays and eolian sand e, and the
entire area has been subjected to erosive forces.
Ennis Draw is the major geomorphic feature in the area. The
present course of the draw has Eormed fairly recently. The paled-channel
was found to be located vest of Che present channel. The low, sandy
terrace-type feature on the we at bank of Ennis Draw is the approximate
eastern boundary of the Ennis Draw paled-channel. The eande are fine-
grained silica and feldspar eolian eande with some clay matrix materials.
For the moat part they are not compacted. At the Bite of the initial
• pit, thin wackestone (silt-clay) layers were found in the eande. Exami-
~ nation of the geophysical Loge indicates that similar wackeatonea exist
throughout the area.