1983-09-01_PERMIT FILE - C1981017

• Permit No: C1981017
• IBM Index Class Name: Permit File
• Doc Date: 9/1/1983
• Doc Name: Mining and Reclamation Plan Approval Package
• Media Type: D
• Archive: No

Ground water quality and water levels are measured in the 12 alluvial
wells in the permit area. Ground water quality data collected from four
of these wells are presented in the permit application. An additional
eight monitoring wells were completed and monitoring commenced in October,
1982.
Cumulative Hydrologic Assessment
The reader is referred to the detailed assessment on this subject located
in the Technical Analysis starting on page 26 and ending on page 43. In
general there are three mines in the Roaring Fork River Valley area that
could affect water quality and quantity. These mines are:
1) Garfield Energy Corp - Sunlight Mine
2) Snowmass Coal Company - North Thompson Creek Mines
3) Mid-Continent Resources, Inc. - Coal Basin Mines
The three underground mines along the Roaring Fork River may impact ground
water quantity by one or more of the following:
- induced inflows into the mines through faults and fractures
which provide communication between the mine and overlying and
underlying aquifers and surface water;
- dewatering of the coal, roof and floor with the advance of
mining; and
- subsidence-induced flows into the mines.
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
these sources depends on porosity and permeability of faults or fractures,
and on the open vertical connection within the faults and fractures
between the coal seam and sources of ground or surface water.
The impacts of subsidence due to mining can be expected to vary in
magnitude and extent. This variation will result from a combination of
numerous natural phenomenon and from the effects induced by underground
mining. Surface water and ground water can both be influenced by
differences in timing of mining and the physical environment. It is
assumed that all mining will result in subsidence at some future point in
time, although surface manifestation may require many years to occur.
Therefore, control and prediction of subsidence are critical, necessary
measures, which should be implemented before and during any mining
activity.
In light of these observations a range of subsidence impact scenarios are
possible. Subsidence related cracking could increase surface and
overburden infiltration rates, diverting water from streams and
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