Emergency closure and dewatering gates include vertical lift (one to two segments) gates, poiree gates, bulkheads, and stoplogs. These gates have seams, edges, and other areas that are favorable sites for zebra mussel accumulation. Potential problems include corrosion, paint deterioration, and unbalanced or excessive loading. The seals at the sill and vertically along the gate, if torn or otherwise unable to function properly, can also cause operational problems. Larger increased loadings, due to inclusion of sediment in mussel accumulations, may occur. There is not a great deal of overload capability designed into the operating machinery for these gates. The manner in which the mussels affect cathodic protection systems is unknown and a potential concern for all large gates.
Detection through occasional inspection is suggested. The gates can be cleaned and painted during regular dewaterings. Antifouling coatings can be used if economically justifiable. Some gates can be raised, inspected, and cleaned if required. Holding the gates in the open position (air drying) will kill any live mussels. The gates at heavily infested locks should be exercised at regular intervals during low-usage periods to assist cleaning and clearing operations.
Navigation Facility Components at Risk