PERMFILE40010

• Permit No: C1981038
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: VOLUME 5A - INFLOW MITIGATION
• Media Type: D
• Archive: No

originates from perched sandstone water bearing strata above the
mined coal seam.
The estimated water seepage into the Orchard Valley mine (4
' gpm in December, 1984) may not be a true expression of the actual
inflow. A considerable quantity of water can evaporate within
the mine. It would be possible to calculate the evaporation rate
1 during various seasons if the changes in temperature and humidity
during a year tin-mine and outside the mine) were known.
' Information regarding the mine inflow was obtained from the
Annual Hydrology and Subsidence reports for 1983 and 1984 and
from discussions with Mr. M. Sakurada, Chief Engineer, Colorado
Westmoreland, Inc.
The other mines within the general area experience the same
types of water inflow into the mine, however, the quantity of
water flowing in the mine is somewhat higher. For example, the
water inflow into the Red Canyon mine of the Grand Mesa Coal
Company was reported to be 12 - 16 gpm during the summer of 1982.
This mine undermined streams within the Surface Creek drainage
and the major inflow is from the coal seam subcropping into the
alluvial aquifer of the referenced stream.
The Somerset mine of the U.S. Steel Corporation reported a
total mine inflow of 150 gpm during 1982. Larger inflows into
these two mines compared to the Orchard Valley mine can be
explained by the presence and undermining of significant
perennial streams.
The Somerset mine undermined Elk, Beaver and Hubbard Creeks,
the last two being significant perennial streams. Most of the
water inflow into the Somerset mine is related to mining under
these drainages.
' Although the available information for the water inflow into
the mines in the area are not from the same year as information
1 referenced for the Orchard Valley mine, the variation of inflow
over several years is not substantially different.
Only one mine in the Somerset mining district, the Oliver
No. 2 mine, has experienced water inflow into the mine that was
too costly to be controlled. In October, 1953, during the
driving of the 6 East entry underneath the joint-controlled
' canyon of Sylvester Gulch, large volumes of water and methane
began to gush from the floor, forcing the evacuation and closure
of the mine (Dunrud, 1976). However, the Oliver No. 2 mine is
located on the south side of the North Fork of the Gunnison River
where the hydrogeologic characteristics are quite different from
the characteristics of the Orchard Valley mine.
The main difference is in the dip of the strata (and
aquifers). On the south side of the North Fork Gunnison River
the strata dips into the valley and, therefore, the aquifers are
discharging into the valley and have typically higher hydraulic
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