REV97125

• Permit No: C1981019
• IBM Index Class Name: Revision
• Doc Date: 3/20/1997
• Doc Name: COLOWYO COAL MINE C-81-019 TR-41 SEDIMENTATION POND REMODEL
• From: DMG
• To: COLOWYO COAL CO LP
• Type & Sequence: TR41
• Media Type: D
• Archive: No

III IIIIIIIIIIIIIIII
999
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Depanment of Natural Resources
1313 Sherman 51., Room 215

Denver, Colorado 80203 Ili~~

Phone: [phone] I
FA%: (3031 832-8106
DEPARTMENT OI
NATURAI
RESOURCE'
Roy Romer

Mazch 20, 1997 Governor
lames S. Lochhead
Executive Director
Mr. James Kiger Michael e. Long

Colowyo Coal Company L.P. DlvlSlOn Direclar
5731 State Highway 13
Meeker. CO 81641
RE: Colowyo Coal Mine (C-81-019)
TR~1; Sedimentation Pond Remodel
Dear Mr. Kiger,
The Division of Minerals and Geology received your technical revision application (TR-41)
requesting modification all of the sediment ponds at the Colowyo Coal Mine. The revision was
deemed complete for purposes of filing on February 27, 1997. The Division has a number of
comments and adequacy questions that should be addressed prior to approval of the revision.
I. Colowyo designed the sediment ponds to facilitate a "treatment structure." Most of the
ponds were evaluated for the post-mining condition prior to seeding the final reclaimed pit area
contributing to the pond. Numerous diagrams were submitted delineating the phases of
reclamation within each watershed. The Division and Colowyo have had numerous discussions
regarding how the phases of reclamation were determined to be used in the SEDCAD+ model.
The Division remains unclear as to how Colowyo and Terra Matrix derived the disturbance and
reclamation acreages depicted on the diagrats and in the SEDCAD+ Model.
The Division reviewed numerous maps and documents in the Colowyo permit in order to
derive a "worst-case" situation for the post-mining conditions at the mine site. In particular, the
Division reviewed annual reclamation reports, the South Hydrology Map (Map 12) and the Spoil
Grading Map (Map 29) to determine a "worst-case" situation at [he end of mining. The Division
estimated within the Prospect Pond watershed between [he yeazs 2007 and 2010 roughly 265
acres of regraded spoil. Colowyo estimated 45 acres of regraded azea in the SEDCAD+ model.
Essentially, at [he end of mining, [he entire East Pi[ will be within the Prospect watershed.
The second phase of pit closure will occur at the West Pit and along the Haul Road
Corridor between the years 2011 and 2013. Most of the drainage will be directed to the East
Taylor Creek Pond and the Streeter Pond. Roughly 124 acres of regrading will are within the