REP38180

• Permit No: C1982055
• IBM Index Class Name: Report
• Doc Date: 8/3/1983
• Doc Name: TR APPLICATION
• From: MLRD
• To: PANOROMA RESOURCE SERVICES INC
• Permit Index Doc Type: Waste Pile/Fill Report
• Media Type: D
• Archive: No

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MINED LAND RECLAMATION DIVISION
DAVID C. SHELTO N, Director
M E M O R
12 August
T0: Susan Mowry ~ ~~
FROM: Jim Pendleton ~ .~ ~-~-~_~
RE: SundanceCoal Com any'~fTechnlcal
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A N D U M ~-l~
1983
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Revision Application;
oat cessing Waste Pile
Pursuant to your request, I have completed a review of a portion of
theSundanceCoalCompany's technical revision application for the Animas
Mine. I have specifically reviewed the company's request for an
amendment to their coal processing waste pile.
SundanceCoal Company obtained approval for construction of a
1,000,000 cubic yard coal processing waste pile within the permit area of
the Animas mine, as a portion of the permanent program permit. That
approval contained a stipulation requiring performance of waste material
`shear strength testing, in order to verify strength values assumed in the
geotechnical stability analysis contained in the original application.
The technical revision presents the results of that testing, completed by
F. M. Fox, Inc. and submitted to the Division for review under separate
submission. Utilizing these amended material shear strength values, the
applicant's engineer now proposes to redesign the coal processing waste
pile to maximize waste storaye capacity.
In completing the redesign and reanalysis of the coal processing
waste pile, the engineer utilized a silnplistlc Homographic stability
analysis technique developed by the U. S. Bureau of Mines for estimating
the factor of safety for tailings embankments and empoundlnents. During
the completion of the oriytnal pile's design analysis, the Division
considered this technique acceptable, because of the conservative
assumptions made concerning waste strength values and because of. the
relatively high safety factors projected.
Ilouever, the proposed redesign of the coal processiny waste pile
represents an increase in pile height from 145' to 320', and a volume
increase from 1 million to 3 million cubic yards. It is my opinion that
the proposed arnenl7id coal processiny waste pile should be the sub,Ject of
an appropriate sophisticated site-specific mathematical slope stability
analysts, prior to approval of the proposed technical revision. Tesarik
8 McWilliams, authors of Bureau of Mines Report of Investigations IJ8564
(1981), relied upon by the applicant in analyzing the pile's stability,
state on paye 12 of their report; "The charts should be a useful tool in
initial embankment design or field work where detailed stability analysis
1s not imperative. However, the charts are not meant to replace the use
of slope stability models where time and resources are available."
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423 Centennial F3wlding. 133 Sherman Slreel Denver. Colorado 80203 Tel. [phone]