REV88963

• Permit No: M1980244
• IBM Index Class Name: Revision
• Doc Date: 2/3/2005
• Doc Name: Adequacy Response Approval Hydrochemistry Qustions
• From: DMG-hhp
• To: DMG-bmk
• Type & Sequence: TR43
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1373 Sherman St, Room 215 C O L D RA D O
Denver, Colorado 80203 D I v 1 5 1 o N o f
Phone: [phone] MINERAL $
FAX: [phone] G): O L O G Y
0.EC LAMATION•MINING
SAFETY•SCIENCE
Date: February 3
2005 Bill Owens
, Governor
To: Berhan Keffelew Russell George
Executive DirecTOr
~i ~
,/ Ronald W. Cottony
From: Harry Posey <-~<~(~ Division Director
/ Natural Resource Trustee
Subject: Adequacy response approval; Hydrochemistry questi s; TR-43; Cripple Creek & Victor
Gold Mining Company, Cresson Project; M-1980-244
This long overdue letter addresses CC&VG's response in Dr. Adrian Brown's letter of September 28,
2004 to TR-43 adequacy issues on hydrochemistry of the proposed Cresson expansion. In short, the
response letter adequately address all of the questions posed in my July 20, 2004 review.
Dr. Brown's response re-states several of the geohydrological assumptions accepted by the Division in
Amendment No. 8. The response refines slightly the water balance model approved in Amendment No. 8
in that the modern accounting shows a greater moisture uptake of precipitation water by the stored waste
rock than predicted in Amendment No 8, thus explaining the lack of increased flow from the diatreme via
the Carlton Tunnel.
The response re-verifies the positive relationship between zinc concentration and flow from the Carlton
Tunnel, and by inference predicts a similar relationship in the future. In that regard, this response corrects
my assertion that an upset condition followed passage of Amendment No. 8, noting that the upset
condition that occurred preceded Amendment 8, and that the elevated zinc discharge noted after approval
of Amendment No. 8, while high, was nonetheless in compliance with standards.
Dr. Brown uses as evidence of future water quality compliance the results of monitoring since approval of
Amendment No. 8. This and the relationships between precipitation, Carlton discharge rate, and zinc
concentration should be sufficient evidence that the zinc concentrations at the Carlton discharge will be in
compliance with water quality standards except perhaps during extreme precipitation events. The
substantial evidence for elevated zinc levels coincident only with high precipitation events prior to both
the Amendment No. 7 and Amendment No. 8 periods is consistent with the requirement that the operation
minimize impacts to the hydrologic balance.
Finally, Dr. Brown's response explains that veins are rare, that they nearly always follow the grain of
major faults, and that they do not comprise separate zones of weakness so were not called out separate
from faults in the stability analysis.
In conclusion, Dr. Brown's responses adequately address all of my identified adequacy issues. Insofar as
my hydrochemistry questions are concerned, TR-43 should be approvable.
Office of Office of Colorado
Mined Land Reclamation Active and Inactive Mines Geological Survey