PERMFILE56529

• Permit No: C1980007
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Exhibit 48 Drainage Modifications
• Media Type: D
• Archive: No

DEPARTMENT OF NATURAL RESOURCES
Dared R. Getches, Executive Director
MINED LAND RECLAMATION DIVISION
DAVID C. SHELTO N, Director
Richard D. Lamm
Governor
June 18, 1986
Mr. Dennis Conn
West Elk Coal Company
P.O. Box 591
Somerset, Colorado 81434
Re: tot. Gunnison No. 1 Mine Technical Revision, File No. C-80-007
Dear Mr. Conn:
The Division has reviewed the revision application submitted June 4, 1986
which addresses installation of an automatic dewatering device in the Bear
Pond. Since this revision entails changes to a designed structure, it will be
processed as a technical revision.
• The revision application has been found to be complete. Please have the
enclosed Public Notice published once in a local paper.
Following are our adequacy comments:
1. Attachment G-Pond Sections should contain a cross section of the
embankment and the emergency spillway, including slope and width. The
subtitle for Attachment G should read Sediment Pond MB-5 Bear No. 1
Portal Area.
2. The applicant (WECC) should submit appropriate acreages of disturbed
areas, curve numbers used, assumptions made, and calculations used to
determine water and sediment volumes.
3. The applicant should submit a stage-storage chart of stage vs. volume
which identifies the following points along the stage axis: 60%
sediment cleanout level, 100% sediment level, and 10 year-24 hour water
volume to verify proper pond design.
4. The applicant should submit peak flow calculations for a
25 year-24 hour precipitation event for Pond MB-5 along with
calculations and sizing information to verify appropriate emergency
spillway size.
5. The applicant should submit calculations used to determine detention
. time and sizing of the dewatering device.
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]