SEDIMENT POND REMOVAL OF PRECIPITATES FROM NEUTRALIZED ACID ROCK DRAINAGE

摘要

Water containing neutralized acid rock drainage flows from the Carlton Tunnel, an 11-kilometer long tunnel that drains the regional ground water table that includes the Cripple Creek Mining District, located the Rocky Mountains of Colorado, USA. Settling ponds are used to remove chemical sediment that forms in the approximately 88 liters/second of water that flows from the tunnel, so that the discharge water can meet Total Suspended Sediment (TSS) water quality limits. The precipitate is made up of micron-sized particles, and is extremely difficult to remove from the water by conventional sedimentation ponds. The behavior of these particles has been evaluated using physical, chemical, and optical testing of the sediment, together with physical and chemical testing of the water conveying it. The results are used to develop an advanced design for sedimentation of colloid-sized particles. The pond system has been redesigned using this method and removes sediment to below the required permit limits.