PERMFILE40846

• Permit No: C1981013
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 06 HYDROLOGY, GEOLOGY, AND WATER QUALITY
• Media Type: D
• Archive: No

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TABLE 12 Water Balance Calculations
NORMAL YEAR WET YEAR
I Eva W I Eva W
] (in) (in) `(in) (in) (in) (in)
Apr 1.66 1.66 0 2.92 2.20 .72
I .day 2.15 2.15 0 2.94 2.94 0
Jun 1.44 1.44 0 3.81 3.81 0
Jul 2.86 2.86 0 4.55 4.55 0
I Rug 2.85 2.85 0 3.07 3.07 0
Sep 1.05 1.05 0 2.02 2.02 0
`
oct l.la l.ia
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13.15 13.15 0 19.39 18.67 .12
Hydrologic Balance Summary - It is estimated that the annual average pre-
cipitation at the Allen Mine is 16.92 inches. Approximately 3.77 inches
of water are lost to evaporation and sublimation during winter months.
Based on the calculations on the previous pages, deep percolation in most _,
years will be essentially zero; that is, all peroipitation will evaporate
from the soil (or runoff). Ouring xet years, as much as .72 inches of water
may be attributed to subsurface runoff. The total area of the dump is
8.6 acres and the estimated total subsurface runoff during a wet year is
approximately .52 acre-feet.
Effect Of Dump On Stream Quality
The above computation indicates that in a normal year, there will be
;. no subsurface runoff (deep percolation) from the refuse pile. Iri a wet year,
the computed deep percolation of 0.52 ac-ft/yr converts to a mean discharge
of 0.01 cfs over a 30 day period and this discharge will enter the stream
during the .high flow period of spring runoff. One small se_p near the east
end of the refuse pile (immediately adjacent to well AL 2-1) was observed
during the spring, 1980. Again, the "worst case" situation is that of low
stream flow and the effects of the discharge from the refuse pile were com-
I• puted using a mean low flow of 3 cfs. Table 13 presents the chemical analyse•
L of a water sample collected from the seep. Concentrations from Table 13 were ,
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