2014-02-14_PERMIT FILE - M2013064 ‎(2)‎

• Permit No: M2013064
• IBM Index Class Name: PERMIT FILE
• Doc Date: 2/14/2014
• Doc Name: Second review of slope stability analysis
• From: DRMS
• To: Varra Companies, Inc.
• Email Name: PSH
• Email Name: TAK
• Media Type: D
• Archive: No

DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
February 14, 2014
STATE OF COLORADO
COLORADO
D I V I S I ON OF
RECLAMATION
MINING
SAFETY
John Hickenlooper
Governor
Bradford Janes
Mike King
Varra Companies, Inc. Executive Director
8120 Gage Street Loretta Pineda
Fredrick, Colorado 80516 Director
Re: Second Review of Slope Stability Analysis, Varra Companies, Inc., Varra - Coulson
Resource Project, File No. M- 2013 -064
The Division of Reclamation, Mining and Safety (Division) staff has reviewed the stability
analysis included with the Varra - Coulson Resource Project 112c permit application and the
adequacy response from AWES, LLC dated January 13, 2014.
The following list describes the information used by the Division as presented in the permit
application to evaluate slope stability for the proposed pit:
• Excavation will occur no closer than 10 feet from the permit boundary, man -made
structures, easements and right -of -ways.
• Excavation will occur to within 25 feet of well heads and related above ground facilities.
• Extraction of sand and gravel to occur at a 1.25H to 1 slope.
• The average depth to claystone bedrock is 40 feet per the mining plan, 45 feet per the
stability analysis report and is as deep as 60 feet.
• No laboratory strength tests were performed on soils at the site.
• The water table is 5 to 10 feet below grade. A static groundwater elevation of 6 feet
below the ground surface was used for the analysis.
• The site will be dewatered during mining activities.
• A clay liner will be constructed at reclamation to create a reservoir.
1. Please provide a plan map indicating the critical cross - section locations used for the stability
analysis models.
2. Please update the stability analysis to include surcharge loads from structures, roads, gas
well facilities, topsoil stockpiles and any other appropriate loads.
3. The typical soil profile used for the stability analysis indicates; two feet of topsoil, four feet
of poorly graded sand, forty -one feet of sand and gravel, a three foot clay lense, fifteen feet
of additional sand and gravel and bedrock at 65 feet below the existing grade. The soil
profile does not match the typical soil profile presented on Page 3 of Exhibit D — Mining
Plan. Please explain this inconsistency and revise the analysis or mining plan accordingly.
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines