1992-07-22_GENERAL DOCUMENTS - C1981017

• Permit No: C1981017
• IBM Index Class Name: GENERAL DOCUMENTS
• Doc Date: 7/22/1992
• Doc Name: Bid Documents ‎(IMP)‎ Proposed Decision & Findings
• Media Type: D
• Archive: No

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characteristics of the adjacent or overlying stream. Perennial inflows are
associated with perennial streams, and ephemeral inflows are associated with
ephemeral drainages. The increased inflows associated with the stream system
are a function of the higher vertical permeability of the strata resulting
from secondary fracture porosity in the stream valleys. The quantities of
mine inflows and of the associated stream depletion are functions of 1) the
area of mine workings adjacent to the streams, 2) the thickness of strata
overlying the mine, 3) the lithology of the overlying and underlying strata,
4) the stream flow characteristics, and 5) the mining methods in the area of
the streams.
Surface Water
The major river of this study area is the Roaring Fork River. The Roaring
Fork joins with the Colorado River at the town of Glenwood Springs. For the
purpose of this CHIS, the mouth of the roaring Fork will serve as the
cumulative surface water impact reference point. All mines considered in this
CHIS are tributary to the Roaring Fork. Please refer to Figure No. 1 for
locations of all affected drainages, and Tables 2 and 3 for surface water
quantity and quality characteristics.
The Coal Basin Mines affects the Coal Creek Drainage. This stream joins the
Crystal River at the town of Redstone. The Snowmass operation is located
within Thompson Creek's drainage basin just north of Coal Basin. Thompson
Creek joins the Crystal River 11 miles downstream from Redstone.
The Crystal River flows toward the town of Carbondale, where it joins with the
Roaring Fork River. One-half mile downstream of this confluence is the
Snowmass Coal Company load-out facility.
Five miles downstream of the confluence of the Roaring Fork and the Crystal
Rivers, is the confluence with Fourmile Creek. The Sunlight Mine is located
on Fourmile Creek, 7.2 miles above this confluence. The Roaring Fork gaging
station (the point defining the study watershed) is located 4.2 miles
downstream of the Fourmile Creek confluence with the Roaring Fork River at
Glenwood Springs, Colorado.
Streams in the region cross the outcrops of the Lower Mesaverde Group (Iles
and Lower Williams Fork Formation) at right angles to the strike of rock
strata. This seems to indicate that these stream valleys have formed in zones
of weakness such as fault and fracture systems, since these strata are
relatively resistant to erosion. Other tributaries flow through strike
valleys formed in less resistant shale units.
Table 2 displays the flow characteristics of the streams affected by coal
mining operations which are considered in the general area.
The Crystal and Roaring Fork Rivers are similar in quality. Total suspended
solids are less than 50 milligrams per liter for much of the year. Total
dissolved solids are 200-500 milligrams per liter (mg/1 ) . With a pH slightly
above neutral , heavy metals and trace elements in solution are low. All of
these are indicators of good water quality.