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of any liner cannot be guaranteed, probably results in a mazginal difference from the hydrologic situation which <br />• would exist if the liner was not employed. <br />The existence of the liner is not believed to have caused the occurrence of the backfill discharge near the CYCC <br />Sediment Pond F. This discharge occurs from a vertical culvert in the spoil which was used for wash down of <br />trucks at the surface mine operation. The reason this discharge began to occur in ] 984 is that pumping of the well, <br />which had maintained the water level in the spoils below the ground surface, ceased at this time. <br />The natural water level in the downdip portions of the spoils is above Bound surface as indicated by several <br />existing backfill seeps and springs in the area which are not updip from the liner. Spoils discharge to ground <br />surface results from recharge to the spoils at higher elevations and the lower permeability of the downdip <br />undisturbed bedrock which causes a buildup of water levels in the vicinity of the old high-walls. <br />Alluvial Aquifers <br />Ground water exists under unconfined conditions within alluvial deposits of the major surface drainages in <br />Twentymile Park. These aquifers consist of shallow deposits of unconsolidated streamlaid material, and are located <br />within the floodplains of the major drainages. In the permit and adjacent areas, such aquifers are located in the <br />floodplains of Foidel, Middle, and Fish Creeks. The unconsolidated streamlaid material, which comprises the alluvial <br />• <br />r1 <br />L J <br />PR 03-06 2.04-22.1 05/07/03 <br />