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exhibiting flow in excess of 20 gpm, and the sample is analyzed for <br />the same partial list of parameters as surface water samples. <br />D. Stream Buffer Zones <br />1. The Division previously approved surface or underground mining <br />activities within 100 feet or through a perennial stream or stream <br />with a biological community. This decision was based on a finding <br />that the original stream channel will be restored, water quality and <br />quantity shall not be adversely affected, and appropriate riparian <br />vegetation will be reestablished. The buffer zone variance was <br />granted for the water pump station on Trout Creek, and for the <br />facilities azea along Oak Creek (4.05.18(1)) For these azeas, the <br />Division also finds that: a) the surface coal mining operations will <br />not cause or contribute to the violation of applicable water quality <br />standazds, and b) during and after mining, the water quantity and <br />quality, and other environmental resources of the stream shall not <br />be adversely affected (4.05.18(1) , as revised). <br />E. Probable Hydrologic Consequences (PHC) of Mining <br />Section 2.5 in Volume 3 of the permit application contains an assessment <br />of the hydrologic consequences of the Edna Mine. Those consequences <br />(with PHC page number or other reference) are summarized below. <br />Projected Impacts <br />1. Post-mining infiltration rate of meteoric water -Annually, 1.95 inches <br />of meteroic water will infiltrate from the ground surface into the <br />subsurface (page 2.5-88). <br />2. Spoil saturation -The infiltrating water will saturate spoil in the toe <br />(northwestern, down-dip end) of each backfilled pit (Exhibit 2.5-25). <br />3. Spoil leachate quality - As the infiltrated water percolates through [he <br />spoil, it will become mineralized to form a spoil leachate having an <br />average total dissolved solids (TDS) concentration of 3000 mg/1 (page <br />2.5-96). This compazes to TDS of less than 600 mg/1 in this <br />stratigraphic sequence prior to mining. <br />4. Dischazge of leachate from pit -From the saturated spoil in each <br />backfilled pit, the leachate will dischazge into the bedrock in the walls <br />of the toe of the pi[, and to the ground surface as spoil springs (Exhibit <br />2.5-25). <br />Edna Mine 20 Permit Renewal No. 4 <br />