GENERAL55781

• Permit No: C1981016
• IBM Index Class Name: General Documents
• Doc Date: 3/14/1983
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

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Both the Blue Ribbon and the Somerset mines have surface facilities and
underyround mine workings located in the Hubbard Creek Drainage. The
combined mininy operations of the Blue Ribbon and Somerset mines may
impact the quality of surface water flowing in Hubbard Creek and in the
irrigation ditches supplied by Hubbard Creek; the Deer Trail Ditch and
the i~iajnik and Klein Uitch. The quantity of flow may be depleted through
the dewatering of faults, fractures and rock strata which are in direct
or in indirect communicator with the alluvium or stream bottom of Hubbard
Creek.
The Somerset Mine has recently mined beneath Hubbard Creek. Inspection
of the underground workings by ChILRD hydrologists showed this portion of
the mine to be making significant amounts of water. At the present time
it is uncertain whether or not surface flows are being depleted.
However, there is a greater concentration of inflows and increased
discharyes associated with the inflow in the Somerset mine workinys below
Hubbard Creek. There is strong evidence that the U.S. Steel Somerset
Mine may already be depleting about 31.1 gpm (44,784 gpd) of the flow in
Hubbard Creek. (See Exhibit E9-3361 "Water Sources in the Somerset Mine"
within the Somerset Mine Permit Application). The Blue Ribbon Mine
workings have not yet impacted the quantity of water in Hubbard Creek.
However, as mining within the Blue Ribon Mine progresses downdip and
towards Hubbard Creek, fractures and low displacement faults, which are
in communication with the Hubbard Creek alluvium and streambed, may be
intersected and thus may cause some depletion of streamflow.
The Mt. Gunnison application has proposed a subsidence protection plan
for the Dry Fork of Minnesota Creek to protect streamflow. The adequacy
of this protection plan was not assessed as a part of the Mt. Gunnison
Kline permit review (this area lies outside of the current, 5-year permit
area). The Division stipulated that site-specific monitoring data
concerning subsidence and its hydrologic effects be taken into account in
the design of any protection plan.
Three perennial streams cross the southern portion of the Mt. Gunnison
life-of-mine area; Lick Creek, South Prong, and Horse Creek. Subsidence
effects could be significant along these stream courses as well, unless
the Mt. Gunnison Mine developes and institutes a subsidence protection
plans for these drainages as well as Dry Fork.
Depletion of Seeps and Springs
Underground mining, even in the absence of subsidence, could cause flow
from intermittent and perennial sprinys to be depleted, or even to go
completely dry. The significance of this effect depends upon the use of
the spring water and its contribution to flow in receiving streams.
Underyround mining at the Mt. Gunnison Mine has a high potential for
affecting springs located in Sylvester Gulch. However, flow from these
springs is already diverted into the Tony Bear Pipeline for use in the
Bear mininy operation, and does not reach the North Fork of the Gunnison.