2011-09-26_PERMIT FILE - C1981012 ‎(24)‎

• Permit No: C1981012
• IBM Index Class Name: Permit File
• Doc Date: 9/26/2011
• Section_Exhibit Name: EXHIBIT 08 HYDROLOGY AND GEOLOGY INFORMATION
• Media Type: D
• Archive: No

52
~' used to characterize the stream inpu~ 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
stream. The sodium adsorption ratio (SAR) downstream of the waste pile was
1 computed by using the computed downstream concentrations of sodium, calcium,
and magnesium.
' The active waste dump rests on alluvial material directly adjacent to
the stream. The alluvium provides a degree of 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
f alluvium. Apparently, the seepage occurred from a water table perched with- . .
l in the dump. Evidence of other perched water in the pile was not observed
and it is believed that the bulk of deep percolation enters the alluvium
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
stream beyond that attributable to the overall elevated salt concentration.
In the case of sodium, a similar elevation was observed in the alluvium at
the Maxraell Mine where it was not possible fora refuse pile to have caused
the change in composition. However, the shift in composition toward in-
creased sulfate was not observed elsewhere. Table 13 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
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, Tow