1992-12-16_GENERAL DOCUMENTS - C1980007

• Permit No: C1980007
• IBM Index Class Name: General Documents
• Doc Date: 12/16/1992
• Doc Name: Proposed Decision & Findings of Compliance for RN2
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

discontinuous, lenticular and laminar sandstones of the
Mesaverde Formation; 4) the Rollins Sandstone; 5) the
coal seam; 6) shallow colluvial surficial deposits ; and
7) fracture zones in bedrock.
The most continuous sandstone aquifers of any
significance in the region are the Rollins Sandstone
and the massive sandstone separating the Upper and
Lower Coal members of the Mesaverde Formation.
However, the latter massive sandstone produces very
little water, as evidenced by the dryness of the Bear
Mine and the lack of springs associated with this
unit. Also, the Rollins Sandstone has been found to
have insufficient yield to sustain ground water supply
wells (Orchard Valley Mine MRP) . This unit lies
270 feet below the F coal seam which has been mined.
The most significant occurrence of ground water in the
region is associated with the alluvium of the North
Fork of the Gunnison River. Significant thicknesses of
alluvial sand and gravel between 30 and 80 feet exist
along the North Fork. Numerous wells are developed in
the alluvium with an average yield of 17.4 gpm. A
pumping test conducted by Bear Coal Company on an
alluvial well near the site of the Bear No. 3 Mine
yielded a value of 806.5 gallons/day/foot for
transmissivity.
Three water quality analyses were conducted for the
Bear No. 3 Mine on three wells completed in the North
Fork alluvium. Two wells exceeded drinking water
standards for total dissolved solids , sodium and
sulfate. The well located closest to the North Fork
(the Bear No. 3 - office well ) showed the lowest levels
of these constituents . This is due to the dilution of
alluvial ground water by North Fork River water at this
well .
Except for areas in the Minnesota Creek Drainage, the
alluvium along the lower reaches of tributaries to the
North Fork is predominantly thin and confined to
discontinuous narrow bands along the stream courses.
The deeply incised channels of these tributaries
restrict the width of the alluvium, while the stream
gradient and the presence of resistant sandstone in the
stream channels limit the thickness and downstream
extent of the alluvium.
Occurrences of ground water have been noted in the
Mesaverde Formation based upon information obtained
from drilling, experience in the mines , and from the
presence of springs and seeps in the region . This
information also indicates that the only potential
regional bedrock aquifer in the general area is the
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