GENERAL48692

• Permit No: C1981019
• IBM Index Class Name: General Documents
• Doc Name: Proposed Decision & Findings of Compliance
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

-1 z-
Colowyo submitted the results of the analysis of interburden below the X
seam as an addition to Exhibit 6, Geological Information.
In a meeting on May 6, 1981, between representatives of Colowyo and the
Division, it was agreed that the Division would review the parameters included
in the Division's overburden monitoring List and provide justification to
Colowyo for the additional parameters requested.
At the meeting on May 6, the issue of bore hole spacing was discussed. CoZowyo's
position is detailed on page 3 of their adequacy responses in Volume VIII
of the application. Colowyo contended that additional bore holes would not
supply any significant additional information due to the Lack of continuity
in the stratigraphy, the isolated and discontinuous nature of ground water
bodies, and the fact that no potentially toxic materials have been identified
in the sampling conducted by Colowyo.
It is the Division's position that the geochemical data provided by Colowyo,
while useful, are not sufficient to characterize the chemical properties of
the overburden. The primary concern at Colowyo is the potential impact of
saline or sodic strata on the plant growth medium. Dve to the discontinuous
nature and relative scarcity of bedrock ground water in the mine area,
potential impact of disturbed overburden strata on bedrock ground water quality
is not a major concern and selective placement of overburden would not be
required on the basis of potential degradation of bedrock ground water.
The laterally discontinuous nature of the strata at Colowyo is characteristic
of a coal depositional environment. The strata are not significantly more
variable than have been encountered at other mines in northwestern Colorado
and throughout the West. Sodic spoils have been identified in the Mesa Verde
Formation in the general vicinity of the Colowyo Mine. For these reasons, the
Division finds the collection of additional overburden geochemistry data from
the area to be mined within the five-year permit term would provide meaningful
and necessary information.
The Division has revised the overburden parameter guide for geochemical
analysis due to the fact that no regional ground water bodies will be impacted
by the Colowyo operations during this five-year permit term. Parameters of
concern are those that have been encountered in Mesa Verde strata at
sufficiently high concentrations to potentially affect revegetation efforts.
In order to collect the additional information on overburden within the area to
be mined, Colowyo has committed to a sampling plan which involves approximately
27 composite samples per year taken from cuttings of overburden blast holes.
The overburden strata to be sampled will be limited to the upper 3 seams,
handled solely by the truck/shovel operation. The truck/shovel overburden
is backfilled on top of the dragline spoil. Since the dragline spoil is
buried at a sufficient depth as to preclude any effects on revegetation, over-
burden sampling of the lower strata will not be required.
The operation is in compliance with the requirements of this section.