REP00790

• Permit No: C1982056
• IBM Index Class Name: Report
• Doc Date: 5/26/1987
• Doc Name: 1986 AHR Evaluation
• From: Cathy Begej
• To: File
• Annual Report Year: 1986
• Permit Index Doc Type: Hydrology Report
• Media Type: D
• Archive: No

Hydrology File - Foidel Creek Mine - 3 - May 27, 1987
Comparison with PHC
The following impacts were identified as the probable hydrologic consequences
of Foidel Creek Mine in the MLRD findings document:
1) Increased salt loading in streams draining the proposed permit area;
2) Increased sediment load in drainages within the proposed permit
area;
3) Temporary changes in the flow regime off Foidel and Fish Creeks;
4) A moderate change in the ion balance of the surface with drainage.
At this time, there does not appear to be any statistically significant salt
loading or sediment loading from the Foidel Creek Mine. While Foidel Creek's
upstream site (No: 14) shows considerably fewer salts, (avg. TDS = 693 mg/1)
than the downstream site (No. 2005/8; Avg TDS = 1912 mg/1) the surface water
site below site 14 and above the Foidel permit area (USGS 09243800) exhibited
similar salt concentrations to the downstream site (Avg TDS - 1885 mg/1)
indicating that the adjacent surface mine was the source of the salinity .
Ponds D and G effectively decrease sediment levels to concentrations lower
than the existing drainages.
Foidel Creek received contributions from Pond D (site 84) all year and
consequently probably flowed throughout the year despite unclear flow data
from 2005 following total drawdown for the purpose of backfilling the western
part of the pit. In 1986, mine discharge waters averaged 0.26 cfs and were as
high as 0.35 cfs while the maximum projected discharge from the Foidel Creek
portal was 0,278 cfs.
While discharges from the mine exceeded projections in the latter half of
1986, discharges from Pond D were lower in TDS and volume as spoils discharges
from the Area 2 Pit did not contribute to Pond D effluent during this period.
The Area 2 Pit, Foidel Creek's waste rock depository, refilled throughout most
of 1986 and the first half of 1987.
The predicted ion balance shift of the surface waters, from minewater
discharge of sodium-bicarbonate-laden waters has not occurred for two reasons:
1) the surface water in Foidel Creek is strongly influenced by calcium-sulfate
backfilled spoils springs water, and in addition; a northward migrating
calcium-sulfate spoils plume from Mine No. 1 is dominating the water quality
of the mine discharge waters: