GENERAL54822

• Permit No: M2000158
• IBM Index Class Name: General Documents
• Doc Date: 1/7/2006
• Doc Name: Review of the Design Report for the Slurry Wall to be constructed
• From: DMG acs
• To: DMG
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman $t., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: (303) 832$106
DATE:
T~:
FROM:
RE:
January 7, 2006 `~
Erica Crosby
Allen Sorenson ~~
JLORADO
VISION O F
IN~RALS
BOLOGY
S~f ETY•ECIENCE
Bill Owens
Govema
Russell George
Executive Director
Ronald W. Cattany
Division Director
Natual Resource Trustee
Review of the Design Report for the Slurry Wall to be constructed at the Sharkey's Lake ,i
Gravel Pit, Platte Sand and Gravel, LLC, S&H Mine, Permit No. M-2000-1 SS r/
The Division of Minerals and Geology (DMG) engineering staff has reviewed the above referenced Design
Reports and has determined that a slurry wall constructed in accordance with the Design Report and the
technical specification contained in the appendices thereto will have a high probability of meeting
performance standards established by the State Engineer for lined gravel pits. As a result, once the slurry
wall is constructed the Operator may become eligible for the 20 percent slurry wall bonding option
described in the DMG Lined Pit Guide2. h3 order to become eligible for the 20 percent bonding option, the
slurry wall must be constructed prior to exposing ground in Sharkey's Pit and DMG must be provided with
a construction report and engineer's certification for the construction. If DMG determines that the
construction report demonstrates that the slurry wall will meet the State Engineer's performance standards,
then the direct cost component of the required reclamation bond for the Sharkey's Lake slurry wall would
be set equal to 20 percent of the replacement cost for the wall. The slurry wall bond for Sharkey's Lake
need not be posted until such time that the Operator will be mining below the water table. Prior to the time
that the Operator will be mining below the water table, and for the time period during which the slurry wall
is being constructed, the direct costs used to establish the amount of bond needed to cover the slurry wall
project would be for grading, topsoil replacement, and revegetation of the acreage disturbed by the slurry
wall project.
For the purpose of estimating reclamation costs for the slurry wall project prior to the exposure of ground
water, the area disturbed by the slurry wall working platform can be assumed to be 60 feet wide by 12,000
feet long, or 16.5 acres. In addition, the Operator must provide, and commit to limiting disturbance areas
to, acreages that will be affected by staging and construction work areas, bentonite slurry preparation areas,
and soil-bentonite backfill mixing areas.
The reclamation cost estimate prepared during consideration of the S&H Mine Permit Amendment AM-01
used the assumption that the slurry wall around Sharkey's Lake would be 10,270 feet long with an average
depth of 33 feet. More detailed investigations conducted for the preparation of the Design Report have
refined the dimensions for the slurry wall, which it is now estimated will be 12,000 feet long with an
average depth of 38 feet. If the Operator intends to complete to slurry wall prior to exposing ground water
I URS Corporation, November 2005, Geotechnical Design Report, "Gravel Pit Lining Project, Platte Sand and Gravel, LLC,
Weld County, Colorado," URS Project No. 22238240
~ Colorado Division of Minerals and Geology, September 2000, "Guide to Specification Preparation for Slurry Walls and Clay
Liners as a Component of a Colorado Mined Land Reclamation Permit"
Office of Office of Colorado
Mined Land Reclamation ARive and Inactive Mines Geological Survey