2D Hydrodynamic Investigation of Olmsted Cofferdams

The Olmsted Locks and Dam are currently being constructed on the Ohio River just downstream of Lock and Dam 53 at river mile 964.4. The original Olmsted construction plan called for an in-the-dry ITD construction using a four-phase cofferdam configuration however, as a cost saving measure, planners changed the original plan to construct the dam using an in-the-wet ITW construction process. Cost and schedule concerns with ITW have US Army Corps of Engineers USACE leaders investigating all options to minimize overall project cost, time, and navigation impacts. Thus, USACE Louisville District LRL has proposed a two-phase cofferdam plan to replace the ITW construction. To evaluate the effect of the newly proposed cofferdam configurations an Adaptive Hydraulics Model AdH was developed to provide current velocities and depths for the Ship Tow Simulator STS for pilots to evaluate the navigability of the proposed cofferdam configurations. In addition, the AdH model was used to evaluate areas of scour around the cofferdams qualitatively. Two stages and discharges were simulated. A maximum velocity through the navigation passes are from 10-18 feet per second fps, and bed shear stresses are estimated at 14-75 Pascals PA. Both could negatively affect the viability of this two-phase cofferdam construction alternative.