GENERAL47069

• Permit No: C1980005
• IBM Index Class Name: General Documents
• Doc Date: 12/31/1986
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE FOR RN1
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

All of the mines located in this portion of the Sand Wash Basin are situated
in upland areas, which have been identified as recharge areas for the
individual aquifers. By extracting coal and its associated overburden, the
mining operations are removing a portion of the recharge area of the aquifer.
The actual mining pits and volume of coal and overburden removed is an
insignificant proportion of each aquifer within the entire basin.
Furthermore, due to the fairly steep dip of the coal, as exhibited at both
Seneca II and II-W Mines, recharge contact time is minimal. As spoils
resaturate and form an aquifer in the backfilled mining pits, the undisturbed
coal and overburden immediately down-gradient is exposed to a great recharge
potential. Due to the generally low permeability of the coal and overburden,
it is not thought that excessive amounts of recharge will be accepted by the
undisturbed aquifer. This physical characteristic will attenuate the
potential quality degradation of the adjacent aquifer due to infiltration of
the relatively high TDS spoils water. Furthermore, the potential recharge to
the consolidated aquifers due to the relatively limited area involved is a
small percentage of the total available amount of water in the aquifer.
Therefore, it is apparent that any adverse impacts due to the introduction of
poor quality water into the Sand Wash ground water basin will be mitigated due
to the relatively small area of impact, the low permeabilities of the aquifers
involved, and by eventual dilution within the basin.
The addition of poor quality water to the alluvial/colluvial aquifers adjacent
to mining will have a local impact on the quality of these aquifers. Spoils
aquifers will discharge to the surface system, which will, dependent upon
local conditions, infiltrate into the associated alluvial/colluvial aquifers.
Generally, these alluvial/colluvial systems are adjacent to the mine site and
are not put to any beneficial use in the immediate vicinity of the mine. The
possibility exists that these aquifers may recharge underlying regional
aquifers, but the majority of flow will be down-gradient toward the larger
stream systems. As the affected alluvial/colluvial water is mixed with the
larger, unaffected alluvial aquifer system, dilution will occur, which will be
sufficient to preclude material damage to the system.
B. 7wentymile Basin
The mines located in the 7wentymile Basin which are considered in this
analysis include the Colorado Yampa Coal Company's Mine No. 1, Mine No. 2,
Mine No. 3 and Eckman Park Mine; 7wentymile Coal Company's Foidel Creek Mine,
Fish Creek Tipple and Middle Creek Mine; Pittsburg and Midway's Edna Mine;
Sunland Mining Company's Apex No. 2 Mine; and a portion of Peabody Coal
Company's Seneca II Mine.
The Apex No. 2 Mine, the reclaimed Middle Creek Mine and the Foidel Creek Mine
are underground operations, while the Edna Mine, Seneca II Mine, Eckman Park
Mine and CYCC Mine No.s 1, 2 and 3 are all area strip operations. All of
these mines, except the Middle Creek Mine, are located at topographically high
points throughout the basin, which are typically described as recharge areas.
The Middle Creek t4ine, which was reclaimed in 1985, is located in a discharge
area. This is evident from portal discharges which have been measured at up
to 2,029 gallons per minute (4.5 cfs).
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