PERMFILE60123

• Permit No: m2004044
• IBM Index Class Name: Permit File
• Doc Date: 8/29/2004
• Doc Name: Reclamation Cost Estimate and Pit Wall Stability
• From: DMG
• To: DMG
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman SL, Room 215 ~ C O L O RAD O
Denver, Colorado 80203 DIVISION O F
Phone: [phone] MINERAL S
FAX: [phone] G E O L O G Y
REC LANATION•NI NING
/ SA FET Y•SCIENCE
DATE: August 29, 2004 /
Bill Owens
Governor
TO: Larry Oehler Russell George
// Executive DIreCYOr
FROM: Allen Sorenson / Ronald W. Cattany
/ Division Director
77// Natural Resource Trustee
RE: ClZeclamation Cost Estimate and Pit Wall Stability Analysis, Aggregate Industries,
Tucson South Resource Gravel Pit, File No. M-2004-044
The Division of Minerals and Geology (DMG) has reviewed the suggested slurry wall bond amount
included in Exhibit L to the Tucson South Pit application. The unit cost of $3.00 per face squaze foot of
slurry wall is appropriate for bonding purposes. However, the Applicant has incorporated eligibility for
the 20 percent slurry wall bonding option described in DMG written guidance and policy memoranda)
into their proposed reclamation bond amount. The rationale for the 20 percent bonding option available
to Operators installing slurry walls for a post mining land use of developed water resources, is as
follows:
An Operator provides design plans, specifications, and a quality assurance plan for DMG review
and acceptance.
The DMG makes a determination that a slurry wall constructed in accordance with the plans and
specifications, and under the approved quality assurance program, has a high probability of
effectively meeting leakage criteria for sealed reservoirs established by the State Engineer.
The Operator must commit to DMG that mining will not intersect ground water until the DMG
has reviewed and accepted the final slurry waft construction report, including quality assurance
test results. The 20 percent bond is a contingency against excessive leakage that maybe
detected during final testing of the sealed reservoir that would require repair or replacement of
potions of the slurry wall, or other actions to seal the leaking areas. Once the reservoir has been
found satisfactory by the State Engineer, the Operator may request release of the 20 percent
slurry wall bond.
The Operator is strongly encouraged to confer with the DMG prior to implementing any changes
to the slurry wall plans or specifications that may occur prior to or during construction. If
substantive changes to the plans and specifications are implemented without DMG concurrence,
and during review of the final construction report DMG determines that the changes diminish
DMG's degree of confidence that the slurry wall will create an effective leakage barrier, the
DMG may determine that the Operator is not eligible for the 20 percent bonding option.
Alternatively, the Applicant may work through the State Engineer's Office (SEO) to obtain approval of
plans, specifications, and quality assurance procedures, and provide documentation of SEO approval to
the DMG. Further, the Operator must provide documentation of SEO acceptance of the final slurry wall
construction report to DMG prior to excavation that would expose ground water in the pit.
I September 2000, "Guide to Specifications Prepazafion for Slurty Walls and Clay Liners as a Component of a Colorado
Mined Land Reclamafion Permit," Colorado Department of Natural Resources, Division of Minerals and Geology.
Office of
Mined Land Reclamation
Office of
Active and Inactive Mines
Colorado
Geological Survey