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For temporary construction disturbance, the effective disturbance area will be minimized to the extent
<br /> reasonably feasible, and the affected stream channel, banks, and any affected floodplain areas will be restored to
<br /> • their original configuration through backfilling, compaction, grading, and placement of armoring (as
<br /> appropriate). Disturbance areas will be reseeded with TCC's standard riparian seed mix.
<br /> For long -term road or railroad crossings, culverts or other appropriate designed flow structures will be installed
<br /> to safely pass the design flows in compliance with applicable provisions of Rule 4.03, and inlets will be armored
<br /> to protect against erosion. If the road/railroad is approved as a permanent postmining feature, the associated
<br /> drainage structures will remain in place. If the road/railroad crossing is to be removed as a part of mine
<br /> reclamation, the affected stream channel, banks, and floodplain areas will be restored at that time, as previously
<br /> described.
<br /> Impacts of Mine Water Discharge
<br /> The relatively continuous discharge of mine water to Foidel Creek constitutes a significant proportion of total
<br /> streamflow during low flow periods. This will result in perennial flow in Foidel Creek, while the mine is
<br /> discharging to Foidel Creek. When the Fish Creek dewatering site is operating (typically limited to the spring
<br /> and early summer runoff period), it can represent a significant portion of the Fish Creek flow. Runoff flows in
<br /> Foidel Creek should increase during the period when the mine is discharging. Projected mine inflows through
<br /> the life of the mine have been re- estimated based on current data and are discussed in the Ground Water PHC
<br /> section, Ground Water Inflow to the Mine. The maximum discharge to Foidel Creek from Pond D and the l ORT
<br /> Boreholes is expected to be approximately 1,200 gpm on a temporary basis, and approximately 400 -600 gpm on
<br /> an averaged annual basis. Maximum discharge from the Fish Creek Boreholes and Site 115 will range up to
<br /> 1,200 gpm, however, average annual discharges will range from 55 to 300 gpm (due to seasonal limitations).
<br /> Mine Discharges
<br /> 411 The 1998 inflows and the estimated future mine inflows are shown in Exhibit 51, Table E51 -4. Projected mine
<br /> discharges are shown on Exhibit 51, Tables E51 -6 through E51 -8. The mining rate used in these projections
<br /> was 8,000,000 tons per year. An increased mining rate will not affect the maximum flow rates, but only move
<br /> them forward in time. The mine groundwater inflow numbers are discussed above in the Ground Water Inflow
<br /> to the Mine section.
<br /> Mine inflows will be discharged and through the Fish Creek and 10 -Right boreholes. During periods when
<br /> these pumps are not operating the sumps below the boreholes fill with mine inflow water. The (1998/1999) Fish
<br /> Creek pool volume was estimated to be 546,000,000 gallons (1675 acre -ft, Ground Water Inflow to the Mine,
<br /> Mine Water Balance). When both pumps at either the Fish Creek or 10 -Right boreholes are running they are
<br /> capable of discharging at approximately 1,000 gpm, although this rate may be increased to 1,200 gpm if
<br /> warranted. The annual average pumping rate is estimated to be 300 gpm for the Fish Creek installation and 400-
<br /> 600 for the 10 -Right installation. Operationally, pumping rates will be maintained at levels sufficient to keep
<br /> the underground water storage reservoirs below the target freeboard elevations relative to the mine seals.
<br /> In June 1999, a system to recycle some of the water that is produced underground was completed. This system
<br /> could recycle over 175 gpm, with an average annual recycling rate conservatively estimated at 100 gpm. The
<br /> system was designed to allow for the addition of some makeup water, if needed to dilute any salt build -up.
<br /> However, it did not take into account that additional water could be used to replace surface uses of water such as in
<br /> the truck -wash, road watering, and the preparation plant, further decreasing the water discharged from Site 109.
<br /> Three cases are presented. In Case I (Exhibit 51, Table E51 -6) all the water is pumped from Site 109 except the
<br /> WMD inflow to the Fish Creek Borehole sump. In Case 2 (Exhibit 51, Table E51 -7), after the water level in the
<br /> sump is lowered, 245 gpm of water is transferred into the sump from the eastern and northern parts of the mine. In
<br /> Case 3 (Exhibit 51, Table E51 -8), water is continuously diverted into the sump, and the discharge rate from Site 1
<br /> • 15 increased, to compensate for the diversion.
<br /> The average water quality discharged from the Site 115 was estimated by incrementally averaging the average
<br /> conductivity in the water in storage with the estimated conductivity of the WMD ground water inflow
<br /> PR09 -08 2.05 -151 04/27/09
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