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6. Leachate impacts on alluvial water ,— Leachate transmitted to Trout <br />Creek alluvium through the unmined wedge of bedrock at the toe <br />of the pit will not cause material damage to Trout Creek alluvial <br />water because the leachate will be sufficiently,diluted by the <br />- fresher, alluvial water (PAP, page 2:5- 104). (Leachate will not <br />discharge to Oak Creek alluvium because Oak C reek is not in <br />hydraulic communication with the former pits.) <br />Leachate impacts on surface, water,- Leachate discharging to the <br />ground surface in spoil springs will not cause material damage to <br />surface water in Trout Creek because the leachate will be <br />sufficiently diluted by the fresher stream water (PAP, page 2.5- <br />104). Maximum TDS of 1186 mg/1 (page 2.5A -7) is predicted for <br />- Trout Creek immediately downstream from the Edna Mine. <br />Leachate will not discharge to Oak Creek surface water because <br />Oak Creek is separated by topography from the former pits. <br />8. Pre -law leachate vs. post -law leachate -. Spoil springs that pre -date <br />SMCRA will hinder recognition of the hydrologic impacts <br />resulting from mining completed since the enactment of SMCRA <br />(PAP, page 2.5 -104). <br />Duration of elevated dissolved solids in leachate — The elevated <br />dissolved solids will persist for a few hundred years (PAP, page <br />2.5 -105). <br />:Observed impacts <br />1. Post - mining infiltration rate of meteoric water — Continuous spoil <br />spring flows totaling several hundred gpm indicate that meteroic <br />water is annually infiltrating into the approximately 1,186.4 acres <br />of permitted disturbed ground surface (annual hydrology reports). <br />Creek or to the bedrock's subcrop beneath the creek's alluvium <br />(PAP, Exhibit 2.5 -25). <br />Spoil saturation The formation of spoil springs indicates the <br />infiltrating meteoric water has saturated spoil in the toe <br />(northwestern, down -dip end) of each backfilled pit (annual <br />hydrology reports). <br />C1980 -001 Edna Mine Permit Renewal No. 6 <br />3. Spoil leachate quality TDS has fluctuated around 3500 mg/1 in <br />the only spoil well, WR -1 (annual hydrology reports). <br />24 <br />