a hydroelectric power installation including a pre - existing gated spillway with upstream bulkhead slots and bulkhead service crane and hydroelectric generating modules configured to fit the existing upstream bulkhead slots . each module including a plurality of turbines , generators , and associated switchgear . the installation may include a trash rake operated on the pre - existing bulkhead service craneway . the hydroelectric installation is configured to meet all of the original navigation project design criteria including generating modules that can be raised above flood water as high as the associated radial gates and that are able to be safely lowered in front of a failed radial gate to serve as the emergency bulkhead the slots for which the modules exclusively occupy .