1993-04-15_REVISION - M1977378 ‎(3)‎

• Permit No: M1977378
• IBM Index Class Name: REVISION
• Doc Date: 4/15/1993
• Doc Name: List of Concerns
• From: DMG
• To: Sunnyside Gold Corp
• Type & Sequence: TR14
• Media Type: D
• Archive: No

seeps or springs, would be a point source discharge and subject to
applicable clean water laws.
In order to determine if any point source discharges are created by
bulkhead installation, Sunnyside Gold must inventory open adits,
shafts and stopes, as well as existing springs and seeps in the
vicinity of the workings to be flooded. The inventory should
concentrate on the east side of Cement Creek as well as its north,
middle and south forks and Minnehaha Creek. Basins, gulches and
creeks to the east and north of the Sunnyside Mine must also be
inventoried in case the Sunnyside workings are connected by zones
of high permeability and preferential ground water movement to the
surface in these areas. The areas to be inventoried would include
Eureka Gulch, Placer Gulch, and California Gulch as well as the
Uncompahgre River basin below Lake Como. The results of the
inventory should be documented as to areal location of adits,
shafts and seeps and where practical measurements should be made of
water surface elevation in shafts, flow rates from discharging
adits and springs as well as water quality information, and
locations of dry adits. At least four quarters of this sort of
baseline information must be collected prior to finalizing the
American Tunnel seal by closing the valve on the by-pass pipe.
Data on water quantity and quality will then continue to be
collected at inventoried locations following bulkhead completion,
and can be correlated with the elevation of the surface of the
rising mine water pool.
In addition, Sunnyside Gold should report on the feasibility of
using groundwater tracers, such as radioisotopes, fluorescent dyes,
or freon in order to determine the location and quantity of any
emergence of mine pool water at the ground surface. The use of
tracers could permit a definitive determination of the degree of
success the bulkhead seals will have in returning the hydrology in
the area of the mine to approximate pre-mining conditions.
Integral to the usefulness of tracers is the method by which they
will be added to, and mixed with, mine pool waters so that there
can be a high degree of confidence that emergent mine pool water
will be traceable.
3 Action Criteria and Contingency Plan
Table 6 contained within the March 12, 1993 Simon Hydro-Search
report indicates that the amount of water leaking around the
American Tunnel bulkhead in the "most likely case" will be . 10 gpm.
If CDOH approves Sunnyside's request to move the discharge point
to the downstream side of the American Tunnel bulkhead, systematic
leakage surveys would undoubtedly be required to demonstrate the
long-term success of the bulkhead seal, and a maximum permissible
leakage rate would be defined. Flow beyond that maximum
permissible leakage would require remedial action by Sunnyside
Gold.
A similar action criteria would have to be developed for any near-
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