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TO PREVENT EROSION AND RE-SILTING BEFORE THE WATER REPORTS <br /> TO THE RIVER. THE PONDS ARE DESIGNED TO HOLD A SEDIMENT <br /> LOAD OF ONE-TENTH ( 1 / 10) ACRE-FOOT OF SEDIMENT PER ACRE OR <br /> DRAINAGE AREA. THE PONDS CAN RETAIN MORE THAN THE RUNOFF <br /> FROM A 10YR-24HR STORM EVENT WITH A FULL SEDIMENT LOAD. THE <br /> RUNOFF WILL BE RETAINED UNTIL THE WATER HAS CLEARED, AT <br /> WHICH TIME THE MANUALLY OPERATED DISCHARGE GATES WILL BE <br /> OPENED. AFTER DRAINING. THE GATES WILL BE CLOSED TO CATCH <br /> FURTHER PRECIPITATION RUNOFF . <br /> WATER QUALITY IS ALSO MAINTAINED THROUGH MEASURES OTHER THAN <br /> SEDIMENTATION PONDS AND DIVERSIONS . FILTERING RUNOFF <br /> THROUGH BALES OF HAY IS A SEDIMENTATION CONTROL METHOD TO BE <br /> USED AS AN ALTERNATIVE TO SEDIMENTATION PONDS. SEDIMENTATION <br /> PONDS ARE EXPENSIVE BOTH IN TERMS OF MINING COSTS AND IN <br /> COST TO THE ENVIRONMFNT AS THEY DISTROY MUCH GRAZING AND <br /> FORAGING GROUND THAT WOULD OTHERWISE BE UNAFFECTED. THE <br /> BALES WILL BE SECURED TO THE GROUND IN A LINE INTERSECTING <br /> THE DRAINAGE FROM REVEGITATED AND LIGHT-DISTURDANCE AREAS . <br /> THE SEDIMENT BUILD-UP BEHIND THE FILTERS WILL BE REMOVED AND <br /> SPREAD OVER THE MINE REFUSE TO ACT AS A SUBSOIL AND BARRIER <br /> HORIZON WHEN THE REFUSE PILES ARE FINALLY REVEGITATED. <br /> SMALL LIGHT-ACTIVITY AREAS HAVE BEEN SURFACED WITH CLEANED <br /> GRAVEL IN ORDER TO PREVENT SILTING OF RUNOFF WATERS . THE <br /> AREAS IMMEDIATELY AROUND THE AIR INTAKE AND EXHAUST SHAFTS <br /> HAVE BEEN SURFACED WITH SIX INCHES OF GRAVEL AS AN <br /> 7 <br />