APPCOR13357

• Permit No: C1992080
• IBM Index Class Name: Application Correspondence
• Doc Date: 6/25/1993
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE
• Media Type: D
• Archive: No

The applicant has installed and will monitor two surface water stations upstream and downstream of
the proposed mine. Both stream flows and water quality samples are collected at these sites. Surface
water discharges from sediment ponds will be monitored under NPDES requirements and copies of
monitoring reports will be submitted to the Division quarterly. The surface water monitoring plan
will be adequate to monitor the effects of mining on the hydrologic balance.
Probable Hydrologic Consequences of Mining and Cumulative Hydrologic Impact Study
Oakridge Energy, Inc.'s Carbon Junction Mine is the only coal mine for which the Division has
received a complete permit application within the Upper Animas River Basin of Colorado. Therefore,
the Cazbon Junction Mine will have no cumulative hydrologic impacts. The following study will deal
with the probable hydrologic impacts of the Carbon Junction Mine on surface and ground water.
Refer to the Description of [he Environment, Operations and Reclamation Plan Description, Geology,
Surface Water, Ground Water, and Alluvial Valley Floor sections of this document for background
information. The following assessment has been made after reviewing all information supplied by the
applicant, public information on the azea, and after making a site inspection of the proposed mine site.
The Cazbon ]unction Mine will impact the quality and quantity of surface and ground water during
and after mining. These hydrologic impacts will be minimal due to the mitigative measures which the
company plans to undertake.
The quantity of surface water will be impacted through evaporation of water in the pit, in sediment
ponds and through diminished spring flows during mining. Following mining and reclamation, the
surface water flow rate (quantity) will approach pre-mining conditions. The impacts to surface water
quantity will be minor given the small drainage azea involved, the minor spring flow contribution, and
the requirement to discharge waters from the ponds.
Ground water quantity will be impacted during mining through the mining of the rechazge aeeas of
aquifers and through depletions of ground water storage (lowering of existing ground water levels)
in aquifers by mine induced pit inflows. Water which would ordinarily recharge the strata upgradient
of the mine pit will be diverted into the pit during mining. The recharge azea within the permit area
is minor in comparison with respect to the entire recharge area of these aquifers up and down gradient
of the mine. Ground water currently stored within the aquifers will be depleted by ground water
flows from [he aquifers into the pi[ (pi[ inflows) as [he mining operation moves down the dip of the
coals. The applicant predicts a maximum inflow rate of 200 gallons per minute which will lower
water levels in the aquifers. Following mining, the pumpage of pit waters will cease and a spoil
aquifer will be established. This spoil aquifer will recharge [he bedrock aquifers and ground water
levels within the aquifers will approach pre-mining levels.
The depletion of recharge will impact the quantity of discharges from springs and seeps downgradient
of the mine, during and for a short period after mining. During mining, some of the ground water
which is tributary to [he springs and seeps will enter the pit, depleting spring and seep flows.
Presently, springs and seeps from the aquifers in the permit and adjacent areas are primarily
discharging to the stream in Carbon Junction Canyon. Thus, there will be a depletion of stream flows.