GENERAL32632

• Permit No: C1981071
• IBM Index Class Name: General Documents
• Doc Date: 3/27/1997
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR RN3
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

Lithologic units in the permit azea aze upper Cretaceous in age and generally lie at the bottom
of the Williams Fork Formation. Rocks in the proposed mine azea lie stratigraphically
between the younger Twentymile and older Trout Creek Sandstones. The Wadge coal seams,
part of the Middle Coal Group, have been mined in the proposed area. The Lennox coal
seam has been removed from parts of the mine area by erosion.
Three economically important coal seams, the Lennox, Wadge, and Wolf Creek coals, aze
located within the locally important Middle Coal Group of the Williams Fork Formation. The
Wadge coal seam has been mined at Mine 1 and Eckman Park. The Fish Creek seam of the
Upper Coal Group was extracted at Mine 2. All pit areas associated with surface mining of
these coal seams have been backfilled, regraded, topsoiled, and reseeded.
Streams draining the permit azea are ultimately tributary to the Yampa River. Fish Creek is a
perennial stream which drains the reclaimed Mine 2 in the northern part of the permit area.
Middle Creek is an intermittent stream which drains a small part of Mine 1 in the eastern part
of the permit area. Foidel Creek is an intermittent stream, which at times has been dominated
by effluent discharges from the Foidel Creek mine, draining the major part of Mine 1 and
Eckman Pazk. Foidel Creek is tributary to Middle Creek. Both Middle Creek and Fish Creek
are tributary to Trout Creek, which joins the Yampa River near Milner. The streams draining
the permit area have been impacted to varying degrees by CYCC's surface mining operations
as well as Twentymile Coal Company's underground mine. Other mining operations exist
both upstream and downstream on Trout Creek and Middle Creek.
The bedrock is mantled on hill slopes by quaternary colluvial deposits, especially at the base
of scarp slopes. Alluvial deposits are present in the lower reaches of Foidel Creek and at the
confluence of Foidel and Middle Creeks. Alluvial deposits are also present along Fish Creek,
Middle Creek and Trout Creek.
Alluvial valley floors have been identified within and downstream of the proposed permit area
on Fish Creek, downstream from the proposed permit area on Foidel Creek and Middle Creek,
on Trout Creek from its confluence with Middle Creek downstream to the Yampa River, and
on upper Middle Creek above the permit area.
The stratigraphy and geologic structure within the Twentymile Park Synclinal Basin control
the ground water flow in the basin. The three regional bedrock aquifers that are present
within the basin are the Trout Creek Sandstone, the Twentymile Sandstone, and the Wadge
coal-overburden aquifer. All three aquifers exhibit artesian heads in the central part of the
Twentymile Park Basin. The water quality in all three aquifers is moderately poor but is
potable and is used for mining, irrigation and domestic purposes.
The alluvium of Trout Creek and its tributaries are important sources of ground water. The
alluvial bodies are used as water supplies, provide sub-irrigation to vegetation, and supply
base flow to the streams. The alluvial bodies are recharged by both the streams and the
bedrock aquifers.
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