2007-05-25_REVISION - M1996008

• Permit No: M1996008
• IBM Index Class Name: REVISION
• Doc Date: 5/25/2007
• Doc Name: Amendment Application
• From: DRMS
• To: DRMS
• Type & Sequence: AM1
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]

DATE: May 25, 2007
/
TO: Kate Pickford .
~
FROM: Allen Sorenson ,--1'~
--
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RE: Geotechnical Re
w
vie
, Western Gravellnc., North R-34 Pit,
Amendment Application AM-01, Permit No. M-1996-008
COLORADO
DIVISION OF
RECLAMATION
MINING
- &-
SAFETY
Bill Ritter, lr.
Governor
Harris D. Sherman
Executive DlreCtOr
Ronald W. Cattany
Division Director
Natural Resource Trustee
The Division of Reclamation, Mining, and Safety (DBMS) engineering staff has reviewed the geotechnical
stability exhibit to the above referenced application. Given the soil types to be excavated, particularly the
Unified Soil Classification System type GP gravel deposit, it is axiomatic that 2H:1 V maximum slopes will
be inherently stable. Any more rigorous slope stability analysis than that provided in the amendment
application is not warranted. However, the Applicant is advised as follows:
The waterline in the pit at the time of reclamation will most likely intersect the overburden strata, and
wave erosion control measures may be necessary.
2. The application states that the pit slopes will be no steeper than 2H:1 V at any time during the mining
operation or reclamation. This is an enforceable permit condition necessary to ensure slope stability.
The DBMS will consider any pit slopes, however temporary they maybe, steeper than 2H:1 V to be a
serious violation of the approved mine plan.
cc: Tony Waldron, DBMS (via email)
Carl Mount, DBMS (via email)
caacs files~[vly Documents 4-19-06 [hruUVorth R-34 Pit geotech review.doc
Office of Office of
Mined Land Reclamation Denver Grand IunQion Durango Active and Inactive Mines