PERMFILE62071

• Permit No: C1982056
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Exhibit 35 Backfill Hydrology Evaluation
• Media Type: D
• Archive: No

•
Q = KIA
Where Q = Flow Rate (ft'/sec)
K = Permeability (ft/sec)
I = Hydraulic gradient (dimensionless)
A = Cross sectional area perpendicular to flow (ft~
In order to yield backfill discharge flow rates in the order of
200gpm, the average permeability of the backfill material must be
in the order of 10'5 ft/sec (Appendix II C). This value is within
the range of measured values and would appear to be reasonable.
The flow net analysis does appear to support the conceptual model
of the ground water flow system in the backfill area.
WATER QUALITY
Reliable water quality data for the backfill material is limited
to data from the Pond F Spring (Table 1). This data indicates
that backfill groundwater typically has total dissolved solids of
about 4000 mg/1 with sulfate, calcium and magnesium the domin-
antions. There is a slight drop in total dissolved solids and
• major ion concentrations during the spring high discharge period
(Table 1). Similar water quality characteristics were found in
the Seneca ZI lysimeter study (Bob Williams pers. comm.)
PROBABLE RYDROLOGIC CONSEQUENCES
The quantification of groundwater flow within the eastern
backfill area at Eckman Park gives a basis for estimating the
probable hydrologic consequences (PHC) of groundwater discharges
for the Eckmand Park and Mine # 1 operations. Updated PHC
analyses for Mine # 2, Mine #3 and the Middle Creek Mines cannot
be projected at this time. Once a comprehensive monitoring
program has been established in 1986 then these analyses may be
performed.
The water balance and flow calculations show that groundwater
flow in the eastern backfill approaches a closed system and that
it probably has achieved a steady state condition when considered
on an annual basis. Furthermore, the discharge from the eastern
area is reasonably well documented as almost all of the discharge
occurs at the Pond F Spring and at the Area 2 Pit. The conclu-
sion that may be drawn from this analysis is that the groundwater
discharges from the eastern backfill area are likely to remain at
the same level as at present.
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