2008-06-13_REVISION - C1994082

• Permit No: C1994082
• IBM Index Class Name: REVISION
• Doc Date: 6/13/2008
• Doc Name: Adequacy Review Comments ‎(Memo)‎
• From: Mike Boualy
• To: Dan Mathews
• Type & Sequence: TR37
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
INTERNAL MEMORANDUM
COLORADO
D IV IS I ON OF
RECLAMATION
MINING
SAFETY
Bill Ritter, Jr.
Governor

TO: Dan Mathews Harris D. Sherman
Executive Director
Ronald W. Cattany
FROM: Mike Boulay Division Director
Natural Resource Trustee
DATE: June 13, 2008
SUBJECT: Yoast Mine Permit No. (C-1994-082)
Technical Revision No. 37 (TR-37)
As requested I have reviewed the TR-37 application package for the Yoast Mine with regard to
hydrology and permanent post-mine features and facilities. I have the following gdequacy review
`comments.
The revised As-Built Report for Pond 010 contains new SEDCAD demonstrations for the 10-
year and 25-year, 24-hour events. The 100-year, 24-hour event is discussed in text but was not
revised with this submittal. The 100-year, 24-hour event demonstration would only be required
if the impoundment meets the size criteria of 30 CFR 77.216(a) or if it meets the Class B or C
criteria for dams in NRCS Technical Release No. 60. However, since the As-Built Report
states that the spillway geometry and peak discharge are based on the 100-year, 24-hour storm
event it would be appropriate to update the 100-year, 24-hour SEDCAD demonstration with
this revision. Please submit a revised 100-year, 24-hour demonstration for inclusion into the
revised As-Built Report.
2. Pond 011 As-Built Report Introduction page references Pond 010 instead of Pond 011. Please
revise this page accordingly.
3. The subwatershed hydrology detail including peak discharges submitted with the revised Pond
011 As-Built Report are not consistent with the existing postmine channel designs for YPM-9,
YPM-12, and YPM-13 which flow to Pond 011. According to our records YPM-9 was
designed in 1998, and YPM-12 and 13 were designed in 2003. The hydrology details for the
channel system should be consistent with the input to the model for the Pond 011 As-Built
report. Likewise the existing channel design for YPM-12 which contains information for
Pond 011 A appears to have inaccurate information regarding structure details including
spillway elevations for Pond 01 IA. Please submit a revised Channel System design for YPM-
9, 13, Pond 011A and YPM-12. Please revise the YPM-12 design accordingly so that it
matches the existing As-Built information for Pond 011A (Exhibit 13-5C).
4. The Postmining channel design SEDCAD4 results (Appendix 13-12.3) was last revised 08/07
with TR-36. The table of contents for this appendix (page 13-12.3-i) does not indicate a design
for YPM-12 and YPM-13. Please update page 13-12.3-i.
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines