2010-09-08_PERMIT FILE - M2009076

• Permit No: M2009076
• IBM Index Class Name: PERMIT FILE
• Doc Date: 9/8/2010
• Doc Name: Second Adequacy Review
• From: DRMS
• To: Venture Resources, Inc.
• Email Name: ACS
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY t/
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
September 8, 2010
Mr. Ryan J. McHale /
Venture Resources, Incz/
P.O. Box 1974
Idaho Springs, CO 80452
A 6 ? COLORADO
D I V I S ION OF
RECLAMATION
MINING
SAFETY
Bill Ritter, Jr.
Governor
Mike King
Executive Director
Loretta E. Pineda
Director
Re: Permit Application Second Adequacy Review, Hukill Gulch Millsite, File No. M-2009-076
Dear Mr. McHale:
The Division of Reclamation, Mining, and Safety (DRMS) has used the geotechnical information contained in
Venture Resources' July 27, 2010 submittal to analyze the proposal to impound mill tailing in Hukill Gulch.
Stability analyses were conducted using Clover Associates Galena for Windows, version 5.01.2.01. The results
of these analyses are enclosed, and are discussed in the following list.
1. Analysis of impoundment with saturated slimes and under static conditions yields an unacceptably low
safety factor of 1.05. The minimum acceptable safety factor given the current degree of certainty of tailing
characteristics, and the variability in tailing properties that will occur under the proposed mine plan, is 1.5
for static conditions and 1.1 under seismic loading.
2. Analysis of impoundment with unsaturated slimes yields a safety factor of 1.33 under static conditions and
1.03 under pseudostatic conditions. The pseudostatic coefficient input was set to the peak ground acceleration
for an earthquake with two percent in fifty years return period at Hukill Gulch, as obtained from
earthquake.usgs.gov/hazards. These safety factors are unacceptably low, and complete dewatering of tailing is
unlikely.
3. Analysis of stability of the proposed geosynthetics interfaces indicates that the geosynthetics are not the
limiting factor for impoundment stability.
The DRMS stability analyses do not consider the potential for liquefaction of the proposed impoundment
during an earthquake, which may be the proposal's most significant limitation. DRMS is further concerned
that revegetation of the steep, south facing impoundment out-slopes will be severely limited by the proposed
1.5H:1 V slopes (refer to Rule 6.3.4(1)(b), Mineral Rules and Regulations of the Colorado Mined Land
Reclamation Board (Rules)).
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines