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REV91274
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REV91274
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Entry Properties
Last modified
8/25/2016 3:12:50 AM
Creation date
11/21/2007 11:09:57 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1980244
IBM Index Class Name
Revision
Doc Date
11/25/1998
Doc Name
CC&VG CRESSON PROJECT GEOTECHNICAL FINDINGS AUGUST 1998 AMENDMENT 7 APPLICATION PN M-80-244
From
DMG
To
BERHAN KEFFELEW
Type & Sequence
AM7
Media Type
D
Archive
No
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<br />• • iii iiniiiiiiiu iii <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman 8r., Room 215 <br />Denver, Colorado 80?03 <br />Phone: 1303) 866-3567 <br />FAx: (3031 832-8106 <br />DATE: <br />TO: <br />FROM: <br />RE: <br />Seismicity <br />Novcntber 25, 1998 <br />Berhan Keffelerv <br />Jim Pendleton <br />CCCQC <br />Augu <br />~~~~~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Roy Romer <br />Governor <br />~ James 5. Lochhead <br />' Executive Diceuor <br />~// ~ Michael B. Long <br />Division Director <br />- Geotechnical Findings - <br />~Cmendment No. 7 Application <br />(Permit No: M-80-244) <br />CC&VG requested that a revised Peak Ground Acceleration (PGA) coefficient be accepted by the <br />Division for use by CC&VG in preparing future pseudo-static stability analyses at the Cresson project <br />The Division reviewed the seismogenic analysis prepared by Golder Associates The Division also <br />obtained the services of Dr. W Pat Rogers, retired of the Colorado Geological Survey, to complete an <br />evaluation of the Golder report. As a res«It of these evaluations, the Division will accept thr, revised 0.088 <br />PGA for application to structures a[ the Cresson project classified as "standard" under the terminology of <br />the Unitied Building Code (UBC) seismic design regulations. However, for application to strictures <br />classifed as "essential" or "hazardous" structures under the terminology of the I;BC scisl;uc design <br />regulations, the Division will require [hat [he currently approved PGA of 0.148 be used m conrple[ing <br />pseudo-static stability analyses. Roads, mine highwalls, overburden storage structures, diserion <br />structures, and the valley leach facility after detoxification, are examples of UBC classified "standard" <br />structures. In the opinion of the Division, the valley leach facility prior ro detoxification is an example of <br />a UBC classified "hazardous" structure. <br />CC&V disagrees with the Division's characterization of the valley leactl facility as "hazardous" Further, <br />CC&V suggests that because [he valley heap leach is a "non-occupied earthworks structure", located in a <br />rural area, with extensive buffer area to prohibit public access, [ha[ the structure is not "hazardous". <br />CC&V has expressed a wish to pursue the appropriateness of the Division's decision regarding UBC <br />classification of the operation valley leach facility outside the framework of Amertdmertt No. 7. CC&V <br />tttay readdress [Iris topic at their discretion. <br />Valley Leach Facility Phase III Expansion <br />C&VG proposed to increase the maximum ore depth from 320 feet to 504 fee[, with overall 1.6H:1.OV <br />sideslope in all areas around the perimeter of the valley leach facility with [he exception of the area up <br />gradient of the Pltase II Toe Berm which area will remain at a 2.SH:I.OV sideslope. Tltis expansion itas <br />been developed to increase the capacity of the valley leach facility to a total of approximately 115,000,000 <br />
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