GENERAL30857

• Permit No: C1981010
• IBM Index Class Name: General Documents
• Doc Date: 2/5/1993
• Doc Name: Proposed Decision & Findings of Compliance for PR3 & RN2
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

SECTION A
Findings Required by Rule 2.07.6(2).

The permit application is accurate and complete. All requirements of the
Act and these rules have been complied with. (2.07.6(2)(a)).
Based on information contained in the permit application and other
information available to the Division, the Division finds that surface
coal mining and reclamation can be feasibly accomplished at the Trapper
Mine. (2.07.6(2)(b)).
The assessment of the probable cumulative impacts of all anticipated coal
mining in the general area on the hydrologic balance, as described in
2.05.6(3), has been made by the Division. This assessment entitled Yampa
River CHIS is available for inspection at the offices of the Division.
volume 4 of the Trapper Mine permit application includes an assessment
of the probable hydrologic consequences of the proposed mining
operation. A brief summary of those consequences is as follows:
Surface runoff will increase due to the mining disturbance but much of
this increase will be contained by the pits and the required sediment
control system of ditches and ponds. Spring snowmelt will cause the ponds
to discharge; However, TSSllevels will be substantially below pre-mine
'~Y levels in most cases du o settling in the sediment ponds. Pit pumpage
7W' will also cause some drainage systems to discharge on a regular basis but
~Z ~~ this water is of generally acceptable quality for stock watering and other
~~~,Q> agricultural purposes and no problems are projected due to this discharge.
The post-mining surface water quality is expected to be close to the pre-
mining surface water quality within a few years after mining. Higher
suspended solids may occur until reclaimed vegetation is established to
control erosion; however, approved sediment control measures will mitigate
this impact. The post-mining pH values are not expected to be
significantly different than baseline values. Total iron and manganese
concentrations are likely to continue to be relatively high at times,
similar to the pre-mine condition.
Following reclamation, springs are likely to develop at the downgradient-
end of the backfilled pits. As of 1993, known spoil springs are present
in the Coyote and the Johnson drainages. Water quality data from these
springs show TDS levels in excess of 3,120 mg/1 and increased
concentrations of Ca, Mg, HC03 and 504. This water would exceed secondary
drinking water standards but is not currently put to that use downstream
of the mine area. Dilution of the spring water occurs during spring
runoff when the springs are most active. Water quality from spoil springs
would exceed irrigation quality limits if used directly but the lack of
current irrigation uses of the water and dilution negates any projected
impact. Spoil spring water is acceptable for stock water and wildlife
usage.
The quality of ground water in the vicinity of the Trapper Mine may
degrade as a result of the leachate generation from the spoils, utility
waste, and municipal waste. If a leachate develops from any of these
sources, it would move downgradient and enter the groundwater system
through the unmined highwall at the north end of the pit areas. The only
major aquifer located downgradient and in direct contact with the spoil
leachate is the Third White Sandstone. If contaminated ground water would
leave the pit areas, the applicant estimates 13 bedrock wells and 2
alluvial wells could be affected. However, the required conditions of
waste placement should insure no significant leachate development from
ground water inflows or percolating surface waters. Adequate ground water
monitoring is in place to detect any ground water problems early-on eo
mitigative measures can be implemented.
Page 11