Chamber gates include miter gates, submersible vertical lift (one to three segments) gates, sector gates, submersible tainter gates, vertical lift gates, and bubbler systems (used for ice and debris control). These gates have many locations that appear favorable for accumulation of zebra mussels. Concerns include corrosion, paint deterioration, and unbalanced or excessive loading. The horizontal seals at the sill and the vertical seals along the gate, if torn or otherwise unable to function properly, can also cause operational problems. The susceptibility of bubbler systems to zebra mussel infestations is unknown. Instrumentation bubblers commonly use some form of nitrogen gas as a drying agent, and bubbler systems used for ice and debris control. The high velocity air flow associated with bubblers is generally a hostile environment for zebra mussels. Project operators, however, should observe the effectiveness of their systems during the active season. Excessively low bubbling rates may mean the bubbler manifold is partially clogged. The manner in which the mussels affect cathodic protection systems is unknown and a potential concern for all large gates.
Locks located on streams that are prone to zebra mussel infestations should be exercised regularly to ensure that the recesses are kept clear of large accumulations of mussels. The gates should be cleaned and painted during normal dewaterings. Antifouling coatings may be economically justifiable. Lock operators should be aware of the possibility of changed mechanical loads. Whenever conditions, such as deflections of the gate leaf, indicate an unusual loading condition, visual inspection using divers may be warranted. Larger increased loadings, due to sediment being combined with mussel accumulations, may occur. There is not a great deal of overload capability designed into the operating machinery for these gates. Potential problems associated with miter gates, above, also apply to submersible lift gates. These gates can be raised, inspected, and cleaned if required. Holding the gates in the open position (air drying) will clear the gates of live mussels. The gates can be painted with an anti fouling paint to reduce future infestations.
Navigation Facility Components at Risk