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Flow hydraulics and mixing characteristics in and downstream from Brandon Road Lock, Joliet, Illinois

July 31, 2018

The Brandon Road Lock and Dam on the Des Plaines River near Joliet, Illinois, has been identified for potential implementation of aquatic nuisance species (ANS) control measures. To provide additional information concerning the flow hydraulics and mixing characteristics of the lock and downstream approach channel, the U.S. Geological Survey performed a detailed study of the site between December 2014 and October 2015, which included the collection and analysis of bathymetric, hydrodynamic, and dye tracer data. Synthesis of these data allowed a characterization of the site for future use in feasibility studies of potential ANS control technologies. The results of this study show a highly dynamic system driven primarily by lock operations but influenced by channel characteristics, industrial withdrawals, and meteorological forcing. Lock operation produces rapidly varying flows in the downstream approach channel, including transient oscillations that produce bidirectional flows. When the lock is not in operation, flows in the approach channel are primarily driven by leakage and wind forcing. Uniform concentrations of dissolved constituents in the lock chamber can be achieved by injection of the constituent into the existing lock filling and emptying system; however, valve and gate leakage can inhibit the mixing at the downstream end of the lock and substantially affects the ability to maintain a treated lock chamber at a uniform target concentration at tailwater level. Proper understanding of these hydraulic factors should be accounted for if the lock is to be used to deliver any dissolved constituent or operated in a way to prevent upstream passage of floating ANS. Moreover, extremely variable flow conditions including bidirectional flows and upstream return flows must be considered when implementing any ANS control technologies in the approach channel.