2007-11-23_HYDROLOGY - M1977300 ‎(6)‎

• Permit No: M1977300
• IBM Index Class Name: HYDROLOGY
• Doc Date: 11/23/2007
• Doc Name: Hydro Eval- Vol. II- AP. E- Mine Pumping Data
• From: Cotter and Whetstone
• To: DRMS
• Permit Index Doc Type: Hydrology Report
• Email Name: DB2
• Media Type: D
• Archive: No

Appendix E - Mine Pumping Data 1
• 1. MINE PUMPING DATA
The first occurrence of groundwater in the Schwartzwalder Mine was recorded in 1959 when an inflow of
17 gpm was encountered in the No. 1 Shaft. After 1959, water was pumped from the mine as required to
maintain dry working conditions, but because treatment of the discharged water was not required, no record
of mine pumping was kept until 1973. Mine pumping records are available, however, from 1973 to 2000.
Pumping from the lowest level of the mine, the spiral decline between 2,200 feet and 1,900 feet was
discontinued on May 19, 1998 and the decline was allowed to flood. Pumping from the 19 Level was
discontinued on May 24, 2000 and the mine has been filling with water since this time.
Groundwater inflow to the mine between 1973 and 2000 varied from about 75 gpm to over 600 gpm
depending on mine development and construction activities (Figure 1). Mine operations that affected the
rate of groundwater inflow and pumpage included:
1. Deepening of shafts and mine expansion. Typically, higher inflows occur during the initial shaft
sinking and mine expansion, and decrease with time as water is drained from storage in the
bedrock. For example, mine inflow increased from about 200 gpm in 1975 to more than 600 gpm
in 1976 during sinking of the #3 shaft. In the 2 years after the completion of the #3 shaft, pumping
from the mine declined to a low of about 300 gpm.
2. Installation of drainage/dewatering boreholes. During the late 1970's and early 1980's drainage
from dewatering boreholes completed on the 19 Level increased mine inflow from about 300 gpm
to 600 gpm before declining to near 300 gpm again in 1981.
3. Plugging of productive boreholes that intersect permeable pegmatites or fractures. In 1994,
• boreholes that intersected pegmatite veins were grouted and mine inflow decreased from about 300
gpm to 150 gpm.
•

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1970 1975 1980 1985 1990 1995 2000 2005
YEAR
Figure 1. Groundwater Inflow to the Schwartzwalder Mine, 1973-1999

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4109B.071113 Whetstone Associates