Upper Mississippi River lock filling and emptying system: hydraulic model investigation

Abstract : Navigation improvements including lock extensions are being investigated for several existing projects on the Upper Mississippi River (UMR). A hydraulic model study was conducted to evaluate filling and emptying system design alternatives for the extension of lock No. 22 and lock No. 25. A 1:25 scale model was constructed to determine the range of lock performance for both locks. The filling system flow capacity was not significantly changed from the original non-extended lock design. The filling time for acceptable chamber performance with the 4.57-m (15-ft) lift was 23.1 min. This filling time was achieved with a 23-min valve. The focus of the study was to determine emptying performance for multiple options of emptying gates built in the extended portion of the lock chamber river wall. Several emptying system designs were studied. The type 2 and 3 design provided the best chamber performance during the emptying operation.