GENERAL32987

• Permit No: C1981044
• IBM Index Class Name: General Documents
• Doc Date: 3/2/1984
• Doc Name: Revised Proposed Decision & Findings of Compliance
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

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The Colorado Water Quality Control Commission has recently promulgated
receiving stream water quality standards (effective March 30, 1983) for the
Williams Fork River and the lower Yampa River. Empire Energy Corporation
received a new Colorado Waste Water Discharge Permit (CO-0034142) in
September, 1982. Although this discharge permit preceded the promulgation of
receiving stream standards, the permit was reviewed according to the
anticipated standards. (Don Simpson, DOH, personal communication to Sandy
Emrich.) Therefore, the mine water discharge would be in compliance with all
State and Federal water quality standards.
Following cessation of mining, the operation is not predicted to discharge
water from the Eagle No. 9 Mine workings and the applicant is required to
provide hydrologic seals for the Eagle No. 5 Mine opening. The applicant
predicts that the No. 5 mine would fill with water in at least seven years,
and the No. 9 mine would take at least three years to refill. Eventually, the
pre-mining ground water flow patterns would be restored and the water from
affected strata would again discharge in its pre-mining locations. However,
this water may be of degraded water quality and may affect the water quality
in the receiving stream/alluvial systems.
E. Hydrologic Monitoring
Section 4.3.5 of the permit application describes the applicant's proposed
surface water monitoring program. Monitoring station locations are shown on
Map IV-13. Hydrologic monitoring is necessary to verify the discussion of
probable hydrologic consequences presented in the application. The purpose is
to make projections of mine impacts both during and after mining and to modify
mining operations, if need be, to minimize impacts to the hydrologic balance.
Several inadequacies in the monitoring plan have been noted,by the Division
and are noted below.
Ground Water
Water level changes in monitoring wells will register changes in the quantity
of ground water and potential depletions in surface waters prior to surface
water monitoring. The Division deems that quarterly monitoring of ground
water levels is sufficient to monitor the impacts of mining, unless there is
an unexpected increase in the rate of depletion. If the ground water levels
show an increased rate of depletion the monitoring frequency will be increased.
The Division deems that annual inflow studies for both the Eagle No. 5 and No.
9 Mines are needed and, thus, have stipulated such studies to be conducted by
the applicant. Inflow monitoring and mine discharge monitoring are essential
in defining the impacts of underground coal mining on both surface and ground
waters. The monitoring of mine inflows aid in quantifying the impacts of
mining on ground water in overlying and underlying aquifers and surface waters
in streams, as well as providing verification of the companies predictions of
mining impacts on ground water. The inflow studies also provide valuable
empiric data necessary to assess and refine predictions of mining impacts on
ground and surface waters for future permitting of mining in the Eagle No. 5