_GENERAL DOCUMENTS - C1981017 ‎(283)‎

• Permit No: C1981017
• IBM Index Class Name: GENERAL DOCUMENTS
• Doc Name: Bid Documents ‎(IMP)‎
• Media Type: D
• Archive: No

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C �.\ -38-
�The three underground mines along the Roaring Fork River may impact
�yround water quantity by one or more of the following:
�&J - induced inflows into the mines through faults and fractures
which provide communication between the mine and overlying and
underlying aquifers and surface waters;
- dewatering of the coal , roof and floor with the advance of
mining; and
subsidence-induced flows into the mines.
Q' Faults and fractures which cut the bedrock strata produce a localized
increase in porosity within the strata. If the faults and fractures do
not become sealed by clays, they may become conduits for the flow of
ground and surface water. When encountered within the mine, faults and
fractures will dewater. The amount of water flowing into the mine from
�hese sources depends on porosity and permeability of faults or
v ractures, and on the open vertical connection within the faults and
q fractures between the coal seam and sources of ground or surface water.
Fault and fracture controlled inflows have been noted and mapped in the
nowmass Coal Company North Thompson Creek Mines application (Figure
3.6.1-5 to -7) , in the U.S. Steel Corporation Somerset Mine application
(Exhibit E8-3366), the Western Slope Carbon Hawk' s Nest Mine permit
application (Exhibit 2.04.7(1 ) or W-IOU6) , the Blue Ribbon Coal Company,
Blue Ribbon mine application (Exhibit T) and the Colorado Westmoreland,
\ Orchard Valley Mine (Revision Submittal of November 18, 1982) . The Mt.
Gunnison No. 1 Mine has encountered only minor inflows from fractures in
the No. 1 portal .
From field observations made by CMLRD hydrologists in the mines in the
adjacent Somerset Coal Field and from information contained in their
respective permit applications, water was noted to seep from the coal,
oof, and floor upon advance of mining in the "B" and "C" seams of the
Somerset ''*line, the "D" seam of the Orchard Valley Mine, the "E" seam of
the Hawk' s nest and Blue Ribbon mines, and "F" seam of the Mt. Gunnison
No. 1 Mine. These sources of mine inflows dry up one to two weeks after
mining an area. The minor amount of water resulting from dewatering of
the coal , roof, and floor indicates that the coals and the overlying and
underlying strata in the Mesaverde Group have very low permeaoilities.
Thus, these strata store and transmit very little water and are not
considered aquifers. Therefore- thP imoact_c of dewat-„�� the coals and
the strata immediately above and below the coals within the tiie_ a9�.e__
Group 41 1 1 nave an iignificant imoact on the hydrologic balances Also
t s nsor inflow resulting from dewatering strata indicated
that these strata will not transmit significant quantities of water which
would result in depletion of surface water sources.