Site-Specific Sediment Deposition Model for Dredging Planning: Case Study of Olmsted Locks and Dam

This study develops a site-specific analysis of sediment transport for the in-the-wet construction of Olmsted Locks and Dam on the Ohio River using the HEC-RAS model. Results from the analysis are used to assess the frequency of need for dredging. Toffaleti's sediment transport function is used herein and is calibrated to the United States Army Corps of Engineers (USACE), Louisville District measurements of sediment concentrations. We apply the calibrated model to historical river flow along the excavated portion of the streambed, during dam construction. We make predictions over a simulation period for deposition in the excavated area without considering the shell placements that are actually made or any dredging to remove deposited sediment. One notable trend on sediment deposition in the excavated area is that approximately half of the long-term predicted deposition occurs within the first six months. Our results show that trapping efficiency of the transported sediment load follow a similar trend starting at less than 10% and dropping to 1% within a half a year. The results of this analysis are useful for other planning dredging operations where in-the-wet construction will be performed.