2009-11-02_INSPECTION - M1977211

• Permit No: M1977211
• IBM Index Class Name: INSPECTION
• Doc Date: 11/2/2009
• Doc Name: CGS Assessment of ne September 2009 Rock Slide at the Pike View Quarry
• From: CGS
• To: DRMS
• Inspection Date: 9/15/2009
• Email Name: BMK
• Media Type: D
• Archive: No

STATE OF COLORADO
COLORADO GEOLOGICAL SURVEY- serving the people of Colorado COLORADO
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Department of Natural Resources PP
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1313 Sherman Street, Room 715 ,
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Denver, CO 80203 Ali
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DEPARTMENT OF
NATURAL
DATE: November 2, 2009 RESOURCES
TO: Berhan Keffelew, Tony Waldron, David Berry
Bill Ritter, Jr.
Governor
FROM: Jon White, TC Wait
Harris D. Sherman
Executive Director
SUBJECT: CGS assessment of new September 2009 rock slide at the
Pike View Quarry Vincent Matthews
Division Director and
State Geologist
At the request of the Colorado Division of Reclamation, Mining, and Safety (DRMS) the
Colorado Geological Survey (CGS) has conducted an inspection of an additional failure of the
quarry wall that occurred on September 13, 2009 at the Pike View Quarry. CGS engineering _
geologists Jon White and TC Wait visited the site on Tuesday, September 15, 2009 with -f-Ac 1 „
0.1 representatives of the mine owner and DRMS. At the time of our inspection, active mining T?r
operations were still suspended due to the previous quarry rockslide of December 2, 2008.
The CGS conducted a site inspection of the quarry rockslide and provided an initial
assessment of the rockslide conditions to DRMS in a letter memorandum dated January 7,
2009. CGS also provided a memorandum to DRMS dated September 10, 2009 that included a
technical review of a slope stability report of the quarry rockslide that was prepared by
CTL/Thompson, Inc. dated May 19, 2009 (CTL/T Project No. CS17341-125). Movement
monitoring graph images for 14 of the 31 monitoring prisms between the dates of 9/9/09 -
9/29/09 were submitted to the CGS via e-mail on October 7, 2009. Certain prisms were lost that
were located in that portion of the south block that failed.
The purpose of this memorandum is to summarize our observations of the continued
movements of the rockslide and provide any other suggestions or recommendations concerning
safety and slope stability at the quarry.
The new rockslide is a retrogressive failure of the headwall and general enlarging of the
December rockslide, which illustrates the ongoing hazard concerns the CGS raised in our
January 7 and September 10 memorandums. Gross downward movement with new offsets
from 15 feet to over 40 feet occurred along the preexisting incipient scarp above both the south