GENERAL50226

• Permit No: C1981021
• IBM Index Class Name: General Documents
• Doc Date: 8/11/1983
• Doc Name: DIV REVIEW OF SWELL FACTOR DETERMINATION SUBMITTED BY WALDEN COAL CO IN RESPONSE TO STIPULATION 6
• From: MLRD
• To: FLATIRON CO
• Permit Index Doc Type: STIPULATIONS
• Media Type: D
• Archive: No

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R ¢nartl D. Lamm
Governor
DEPARTMENT OF NATURAL RESOURCES
D. Monte Pascoe. Executive Duecior
MINED LAND RECLAMATION DIVISION
DAVID C. SHELTON, Dlrertor
July 26, 1983
T0:
FROM:
RE
Mike Savage 1
Jim Pendleton
Review of Bo Co s Swell Factor Calculations and
Correspondt rmlt Revisions
Pursuant to your request, I have reviewed the swell factor determination
and corresponding permit revisions submitted by Walden Coal Company for
the Bourg Strip Ptt. These calculations, prepared by Robillard and
Associates, Inc., consultant to the operator, present the results of a
stereophotogrammetrlc analysis. The analysts determined that 1,160,000
loose cubic yards of overburden and topsoil have been produced from a
1,020,000 bank cubic yard excavation. Production records demonstrate
that approximately 141,000 bank cubic yards of coal were included within
the excavated material.
The operator's subsequent calculations demonstrate that an overall
intrinsic swell factor of 32X has been experienced to date. Ny
calculations determinated that this represents an overall bulking factor
of 1.137. The applicant's original assumption of an Intrinsic overburden
swell factor of 23X would have resulted in a corresponding overall
bulking factor of 1.06. Therefore, the operator's backftlled volume
currently exceeds pro~ectlons by approximately 80,000 cubic yards. If we
assume the operation to be approximately 2/5 complete, the life-of-mine
might result in approximately 200,000 cubic yards of swollen backf111 in
excess of the amount originally predicted.
The amended permit application states that the operator believes the
implications of this error to be insignificant. In my opinion, the
Information submitted is inadequate to ,~ustlfy that statement. I
recommend that you require the operator to develop a worst-case
alternative backfilling and grading plan, in order to demonstrate that
the additional pro,~ected swollen backftlled volume can be accommodated
without creating an environmental or slope stability problem.
/mt
cc: Brian Munson
Doc. No. 4543
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]
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