ASHTABULA RIVER SEDIMENT REMEDIATION PROJECT: SLURRY TRANSPORT, DEWATERING, DISPOSAL, AND WATER TREATMENT

摘要

In September 2006, contaminated sediment dredging commenced on the Ashtabula River Remediation project under the authority of the Great Lakes Legacy Act. As part of this construction project approximately 382,000 cubic meters of contaminated sediments were hydraulically dredged from the river, transported 4.3 kilometers overland through a double-walled HDPE pipeline with three 500 Hp centrifugal booster pumps, dewatered utilizing geotextile tubes, and disposed of in a TSCA-permitted landfill specifically constructed for this project. Water from the dewatering process was treated through a 19,000 liter per minute water treatment plant, permitted by OEPA and operated under an NPDES permit. Dredging was completed on October 14, 2007. Dredging and processing operations were scheduled to take place on a 24-hours per day, 6 1/2 days per week (scheduled 1/2 day off per week for maintenance). Production during the 2006 dredging season average less than 610 cubic meters per day due to difficulties in the transport, dewatering, and water treatment systems. Upgrades to these systems during the 2006/2007 winter shutdown greatly improve production rates during the 2007 dredging season. Dredging production during the 2007 dredging season averaged over 1,760 cubic meters per day. Technical details and performance characteristics are provided regarding the transport, dewatering, disposal, and water treatment operations. Additionally, the authors discuss lessons learned during the operations that improved performance in the later stages of the project and will inform decision-making on future sites.