Repair of Dam Intake Structures and Conduits: Case Histories

Based on a survey of inspection reports, 29 percent of the maintenance and repair problems at Corps dams were observed in intake structures and conduits. Repairs to these structures did not perform as desired in better than 40 percent of the reported efforts and with better than 21 percent reported as failed. A number of products whose manufacturers literature indicated that their products were suited for application in a wet environment such as that found in intake structures and conduits failed. In some instances, the repair technique was at fault. In others, the product failed to perform as indicated. This report documents selected repair efforts to intake structures and conduits and presents them in a case history format that includes a project description and a history of the repair efforts. The project description identifies principal project features and gives a detail description of the deficiency being repaired to include its history and cause if known. The descriptions of repair efforts are presented chronologically for each project and include a detailed description of the repair products and techniques used and the performance of the repair if known. The two most common types of concrete deficiencies being repaired were leakage from cracks and joints and cavitation erosion damage to conduit passageways immediately downstream of gates. The most successful method documented for reducing leakage through both cracks and joints was chemical urethane grouting. The most successful method documented for withstanding cavitation damage was resurfacing of damaged area using a product call Belzona Magma Quartz. However, before a recommendation can be made, laboratory testing is needed to further substantiate the quartz products potential for cavitation repair. Also, because this product is extremely expensive, it may be more economical to repeat the resurfacing on a routine basis using an inexpensive patching material.