Culvert valves and racks include navigation project components, such as tainter valves, butterfly valves, and vertical lift valves. High velocities and regular use inhibit attachment so that these valves are considered unlikely to have problems with zebra mussel fouling. Added weight for operating machinery, improper sealing, seal deterioration, corrosion, and paint deterioration are potential (but unlikely) problems for these valves and racks.
Normal usage, or periodic operation for low usage locks, should keep the sealing tracks clear. Valves can be cleaned on scheduled dewatering and rehabilitated. An upstream bulkhead must be installed before inspecting and cleaning. Therefore, early detection and careful observations of performance are needed. Once the bulkhead units are placed, the gate can be fully exposed to atmosphere, cleaned, and a protective coating applied, as required. High pressure water and scraping may be needed. Seals and sealing surfaces can also be inspected and repaired. In periods of low flow, the gates can be operated regularly to clean the side and bottom sealing surfaces.
Racks with large bar spacings (commonly, 15 cm) that are regularly exposed to high velocity flow, such as at lock culvert intakes, are unlikely to accumulate large numbers of zebra mussels. When accumulation does occur, then unbalanced flow, excessive loadings on the bars, corrosion, and slower operation may result. A program of operation can be instituted for rarely used locks. Antifouling coatings may be worthwhile for some locks, particularly those that are rarely used. Removable screens can be raised, cleaned, and replaced.
Navigation Facility Components at Risk