1. The restoration of concrete surfaces with sprayed concrete is an efficient, highly mechanized, and comparatively economical method; and the work is of high quality. 2. The described method may be expeditiously employed in repairing surfaces while operating the structures; for example, in repairing lock chamber walls while operating the locks. 3. When it is possible to lower the water level in canals, sprayed concrete may be recommended as the most expedient method of placing a monolithic cover on stone paving or on a gravel base course; and also for resurfacing the protective slope covering. 4. Locating the equipment and materials on a self-propelled ship provides the greatest convenience and mobility for working on existing structures.