REP30334

• Permit No: C1981022
• IBM Index Class Name: Report
• Doc Date: 2/19/1982
• Doc Name: REVIEW OF THE GEOTECHNICAL ASPECTS OF THE SOMERSET MINES PERMIT APPLICATION SUPPLEMENTAL SUBMITTALS
• From: MLRD
• To: TOM GILLIS
• Permit Index Doc Type: SUBSIDENCE REPORT
• Media Type: D
• Archive: No

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DEPARTMENT OF NATURAL RESOURCES 999
. D Monte Pascoe Executive Dvenor I
MINED LAND RECLAMATION DIVISION
DAVID C. SHELTON Director
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R~cna~c D. Lamm
Gove~nc~ February 19, 1982
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T0: Tom Gillis
FROM: Jim Pendleton ~^~"~
RE: Review of the otec cal Aspects of the Somerset Mine's Permit
Application mental Submittals
i
Pursuant to your request, I have reviewed the geotechnical aspects of the
supplemental submittals made by United States Steel Corporation for its
Somerset Mine. Z forward the following cof:mients for your consideration.
.i
Backfilling and Grading (a portion of Findings Section XVII)
Underground L~velopment waste Pile
The existing operations at the Somerset mine include the disposal of waste
in a pile within the east yard. Underground development waste is generated
in small quantitu (500 cv. yds. per year) by occasional roof fall. The
applicant proposes to dispose of all future underground development waste
in a waste disposal pile located within the area of the existing C-seam mine
portals, which are scheduled to be sealed and abandoned within the near future.
In addition, the applicant has proposed, in a supplemental submittal, to
relocate approximately 8500 cubic yards of waste, currently stored in the
yard at Eik Creek, to the new disposal pile. The total projected pile
capacity, depicted in cross-sections and plan, is 23,000 cubic yards. This
volume has been projected to accormradate all waste expected to be produced
during the remaining 20 years of the Somerset mine's life.
The applicant will place waste in maximum 2-foot thick horizontal lifts and
track compact that material. The foundational area of the pile has been the
site of previous disturbance for the construction and operation of the C-seam
mine's portals and bench area. The facial slope of the proposed pile will
vary from 6:1 (horizontal to vertical) near the east end cf the pile to a
maximum slope of 3:1 (horizontal to vertical) in the area of the existing
portal openings. Topsoil has been removed prior to the advent of the current
regulations and is no longer available for use in reclamation. However, the
applicant proposes to remove 3 feet of subgrade material to be stockpiled and
used to produce a 2-foot thick non-toxic cover for the completed waste pile.
In response to the Division's Preliminary Adequacy Review, the applicant
supplementally submitted a stability analysis for the proposed development
waste pile. However, this analysis does not include a geotechnical investigation
of the proposed site. No surface pit sampling or angering was conducted. No
subsurface site hydrology is reported within the underground development waste
a23 Centennial Building, 1313 Sherman Street Denver', Colorado 80203 Tel. [phone]