2008-08-21_REPORT - C1980007

• Permit No: C1980007
• IBM Index Class Name: REPORT
• Doc Date: 8/21/2008
• Doc Name: 2007 AHR Review
• From: DRMS
• To: Mountain Coal Company
• Annual Report Year: 2007
• Permit Index Doc Type: Hydrology Report
• Email Name: TAK
• Media Type: D
• Archive: No

Require-

Requirement Requirement
citation ment
complied
Comment
with 7
es/no
Q. Restoration of
ground water CDRMS Mining in the permit area cannot be expected to significantly decrease infiltration of snowmelt or
recharge to regulation yes runoff into the subsurface. Monitoring data do not show an impact on recharge.
approximate 4.05.11(3)
reminin rate
Data from the down-gradient B-seam monitoring well 1-11-1 indicates there have been no
significant impacts to bedrock ground water quality outside the permit area. TDS in this well in 2007
R. Prevention were less than the premining 2,700 mg/1 level found on the mine in the B seam. The potentiometric
adverse impacts CDRMS surface of the B seam may be depressed due to mining near the Box Canyon workings as shown by
ground
water regulation yes dropping water levels in B-seam wells 01-11-1 and RAV-4b. Nearby E-seam well 03-11-1, however,
systems
s
outside 4.05.11
does not show a drop in water level. Alluvial (colluvial) monitoring wells that are completed in North
the permit area Fork River valley downgradient from the mine (GP-3 and GP-4) were dry when sampled in 2007, as
in previous ears.
S. Prevention of
impacts to CDRMS
ground water regulations
that adversely 4.05.1(2) and yes
impact the 4.OS.l 1
postmining
land use
Monitoring data indicate impacts to ground water and surface water have been the minimum that can
be expected for an underground coal mine. The most significant hydrologic impacts from mining at
West Elk in 2007 were:
1) As in previous years, mining in long-wall panels may have been the cause of water level
T. Minimization of fluctuations in monitoring wells located within a few hundred feet of the workings.
disturbance to CDRMS 2) In 2007, TDS in North Fork surface water showed no change where the stream flows past the
the hydrologic regulation yes mine, remaining near 110 mg/1 above and below the mine. In past years, the mine's
balance within
and adjacent to 4.05.1(1) discharge of underground mine water and surface runoff into the North Fork of the Gunnison
the permit area River has occasionally raised the concentration of dissolved solids in the river. The increase
was probably greatest during pumping of underground mine water in Sylvester Gulch which
flows to the North Fork. The increase probably remained in the 10 to 75 mg/1 range and did
not exceed levels predicted in DRMS's Cumulative Hydrologic Impact Study for the North
Fork. As explained in item U below, monitoring data indicate North Fork TDS remained
well below a level of concern for irrigation water.
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