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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used to characterize the stream input from the dump.
The estimated changes in selected water quality parameters as the result
of deep percolation in a wet year are shown in Table 14. Even this worst-
] case estimate indicates a very small effect on the water quality in the
J stream. The sodium adsa.rption ratio (SAR) downstream of the waste pile was
~ computed by using the computed downstream concentrations of sadiun, calcium,
f
I and magnesium.
1 1 The active waste dump rests on alluvial material directly adjacent to
the stream. The alluvium provides a degree pf storage, in addition to that
~~ in the dump itself, and tends to cause seepage into the stream to occur at
a reduced rate, but over a longer period of time. Thus, the discharge of

~ 0.01 cfs from the waste material, based on a 30 day seepage period, may be
' larger than actually occurs. The small seep observed during this investi-
gation issued from the refuse pile near the contact between the waste and
the native ground., and was several feet higher than the water table in the
alluvium. Apparently, the seepage occurred from a water table perched with-

in the dump. Evidence of other perched water 1n the pile was not observed -,
and it is believed that the bulk of deep percolation enters the alluvium
I before discharge to the stream. Figure 14 compares the composition plots
of alluvial waters with that in the adjacent stream. The alluvium shows
concentrations of sodium and sulfate that are elevated in respect to the
l stream beyond that attributable to the overall elevated salt concfantration.
In the case of spolum, a similar elevation was observed in the alluvium at
the Maxwel_1 Mine where 1t was not passible fora refuse pile to have caused
the change in composition. However, the shift in composition toweird in-
~ creased sulfate ~nas not observed elsewhere. Table l: shows a substantial
concentration of sulfate in seepage from the waste pile and, in all probability,
the seepage is responsible for the shift in composition.
The elevated levels of sulfate in the waste dump are somewhat: surprising
i in view of the fact that all other data on subsurface waters indicate sodium-
bicarbonate waters. There is evidence to suggest that the observed sulfate
~ does not derive from sulfuric acid production from pyrite. Four samples
of the waste dump materials were analyzed for pyritic sulfur, showing only
,
low quantities ranging from 0.03-0.04 percent. Also, the pH of 8.0, low