GENERAL41890

• Permit No: C1982054
• IBM Index Class Name: General Documents
• Doc Date: 7/5/1983
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

-31-
Pueblo Coal, Inc. also proposes to dispose of coal processing waste, generated
at a washing plant on-site, within the backfilled mine pit. The applicant
proposes to restrict placement of processing waste within the pit backfill to
areas more than 20 feet above the lowest observed pit water elevation. The
geotechnical investigation and mathematical stability analysis, contained
within Appendix 5-6 of the amended permit application, also evaluated and
projected static slope safety factors for the proposed post-mining topographic
configuration of the mined pit. Kenneth C. Ko and Associates projected a
general safety factor of 1.8 for the backfilled pit configuration. However,
their analysis did not consider the inclusion of coal processing waste within
the backfilled spoil. In response to Division adequacy comment regarding this
topic, the applicant projects little stability effect due to the placement and
inclusion of coal processing waste. Pueblo Coal, Inc., further observes that
they do not believe it feasible to mathematically analyze minute changes which
might occur due to the placement of coal processing waste materials within the
backfilled spoil. In order to assure compliance with the slope stability
requirements included within Rule 4.14 of the permanent program regulations,
thes Division deems it necessary to impose the following stipulation upon
approval of the Carbon Junction Mine permit.
Stipulation No. 7
THE DIVISION DIRECTS PUEBLO COAL, INC. TO CONFORM WITH THE FOLLOWING
CONDITIONS WHEN PLACING COAL PROCESSING WASTE WITHIN THE BACKFILLED SPOIL
OF THE SURFACE PIT AT THE CARBON JUNCTION MINE:
THE PLACEMENT OF COAL PROCESSING WASTE IS TO BE RESTRICTED TO
PREPARED SURFACES WHICH ARE TO BE LEVEL OR DIPPING SLIGHTLY TOWARD
THE HIGHWALL OF THE PIT. THESE SURFACES SHALL BE ROUGHENED BY
SCARIFYING IN A DIRECTION PARALLEL TO THE STRIKE OF THE FINAL
RECLAIMED TOPOGRAPHIC SURFACE OF THE MINED PIT AREA.
COAL PROCESSING WASTE SHALL BE PLACED IN HORIZONTAL LIFTS NOT TO
EXCEED 1 FOOT IN THICKNESS AND COMPACTED TO 90% OF THEIR RELATIVE
MAXIMUM DENSITY, AS DETERMINED USING A.S.T.M. STANDARD TEST
DESIGNATION D696.
COAL PROCESSING WASTE SHALL BE DISSEMINATED WITHIN THE PIT
BACKFILL.
BODIES OF COAL PROCESSING WASTE SHALL BE ELONGATED WITH THEIR LONG
AXIS PARALLEL TO THE STRIKE OF THE FINAL RECLAIMED TOPOGRAPHIC
SLOPE OF THE BACKFILLED PIT.
BODIES OF COAL PROCESSING WASTE SHALL NOT EXCEED 100 SQUARE FEET
IN CROSS-SECTIONAL AREA, AS MEASURED ON CROSS-SECTIONS
PERPENDICULAR TO THE STRIKE OF THE FINAL RECLAIMED TOPOGRAPHIC
SURFACE OF THE MINED PIT AREA.
COAL PROCESSING WASTE SHALL NOT BE DEPOSITED WITHIN 20 FEET
VERTICALLY FROM THE FINAL RECLAIMED SURFACE WITHIN THE MINED AREA.