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

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5.0 POST MINING HYDROLOGIC CONDITIONS
The hydrogeologic characteristics of the Orchard Valley mine
where the coal seams and the sandstone strata are outcropping and
dipping out of the valley assure that the abandoned mine will not
be discharging water. This is confirmed by water level
measurements in the Farmer's mine, in all deep monitoring wells
within the permit area and by general development of the
potentiometric surface in the deep water bearing strata.
After abandonment of the Orchard Valley mine the water will
be seeping slowly into the mine and filling the mine to an
elevation of approximately 7,100 feet. At the time of mine
abandonment the mined out volume will be more than 300 million
cubic feet. The mine flooding will be very slow and it would
take approximately 130 years to fill the mine to an elevation of
7,100 feet with only natural inflow. The mine flooding would be
substantially faster if an out-of-mine source of water is used to
fill the mine. With an addition of 38.0 gpm available at the CWI
well field in Stevens Gulch, the mine filling will be reduced to
approximately 61 years.
The mine flooding could be altered by the following
measures:
o commencement of flooding of particular mine
sectors during the mine life;
o intensified flooding of selected sectors of
the mine sealed from the other parts of the
mine.
Mine flooding will be discussed with the regulatory agencies
before the mine abandonment and more detailed flooding plans will
be prepared.
The time necessary for the filling of particular sectors of
the Orchard Valley mine with only natural and natural and
artificial sources is expressed in the following table.
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