1994-10-21_GENERAL DOCUMENTS - C1980007

• Permit No: C1980007
• IBM Index Class Name: General Documents
• Doc Date: 10/21/1994
• Doc Name: Proposed Decision & Findings of Compliance for PR5
• From: Jumbo Mountain Lease
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

has been made by the applicant, and is found in Section
2.05.6(3) of the permit application. The operator has
projected the impacts based on past experience, expected rates
of water use and water discharge, hydrogeologic conditions
associated with refuse disposal areas, location and extent of
surface disturbance and hydrogeologic conditions associated
with underground mine locations.
During the past two permit terms, the West Elk Mine has mined
the F seam. During the next five years, West Elk will
primarily mane the B seam. Activity in this seam will involve
longwall mining methods, with very little or no activity in the
F seam.
The Probable Hydrologic Consequences section of the permit is
divided into two main subsections: Ground Water Effects and
Surface water Effects.
a. Ground water Effects
There are no immediate demands on ground water in the
vicinity of the West Elk Mine. Domestic water for the mine
will be supplied by surface water from the North Fork of
the Gunnison River, as there is limited potential to use
ground water as a resource. The primary concern with
ground water quality and quantity is the possible impact on
springs, the potential for mine water discharge and ground
water quality impacts in the mine facilities area.
The underground mining methods in use at the West Elk Mine
can affect ground water in two ways. First, development
mining in areas where ground water is present in or near
the coal seam can cause localized movement of this water
into the: mine workings. - To date, ground water movement of
this type has occurred in areas of low cover which are
highly fractured (near outcrops and near stream channels)
and where sandstone channels bearing water immediately
overlie the coal seam. Secondly, retreat mining can cause
subsidence and the fracturing of overlying ground water
aquifers. Again, water usually moves into the mine
workings. The permeability of the F and B seam and
overlying strata is very low and the areal extent and
quantity of water stored in these units is small.
Prior to construction of the mine, the applicant made an
estimate of mine inflow by using preliminary pump test
results and the McWhorter hydrogeologic model. The mine
flow estimates assist in identifying the magnitude of mine
discharge and to assess the potential impact on natural
patterns of ground water recharge and discharge.
The operator at the West Elk Mine expects that mine inflows
will increase at a rate slower than the McWhorter model
predicted for advancing mine workings. Most of the inflow
has occurred along the subcrop in the same location each
year. The inflow is seasonal and varies with the magnitude
of seasonal precipitation. Inflow to the advancing mine
workings has been minimal and unmeasurable. The experience
near the F seam subcrop indicates that the colluvium, coal
and bedrock are recharged locally.
In the past, the West Elk Mine has experienced three types
of mine inflows. The first type of inflow is due to
primary permeability which is ground water flow through the
competent portions of the F seam and lower Barren member.
The second type of inflow occurs in the coal seam and
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