Zebra Mussel Control Facilities

Client: City of Baltimore

Location: Baltimore, Maryland

Services: Environmental engineering

In October 1993, the City of Baltimore selected KCI to design four Zebra Mussel Control Facilities in the State of Maryland. The measures were necessary to guard against the infiltration of a mollusk—Dreissena polymorpha, commonly known as the zebra mussel—into local reservoirs and river supplies, which provide raw and finished water to more than 1.6 million people in the City and five neighboring counties.

Zebra mussels were first sighted in the United States during the mid-1980s, apparently transported from Europe into the Great Lakes in the ballast water of freighters. At that time, few municipalities realized the significant threat the intruder posed or devoted the resources necessary to control the mussels, which multiply at exponential rates. With the species capable of producing as many as one million eggs per year, droves of free-swimming larvae called “veligers” attached themselves to the intake systems of hydroelectric facilities, refineries, steel mills, and automotive plants. The mussels quickly clogged gratings, valves, and pipes and fouled water supply and fire protection systems, causing critical water shortages and prompting emergency appropriations to remove the mollusk.

Since zebra mussels can survive out of water for several days, neighboring regions began worrying that the mollusk, caught up in the bilge of commercial or recreational boats, or attached to hulls, might be transported to new sites. Considering the mounting costs of measures to remove the mussels, concerned municipalities began investigating preemptive measures to counter the spread of zebra mussels in their areas.

Under the direction of the City of Baltimore Department of Public Works, the project team began studying and designing treatment systems and helping the City expand a public awareness campaign to control the infiltration of mussels into the reservoir system. Within nine-months, the team completed the research and design phase in accordance with a fast-track schedule, and the City awarded a construction contract to build four zebra mussel control facilities—three chemical treatment facilities located at the Liberty and Loch Raven reservoirs and the Susquehanna River and a thermal control facility at the Prettyboy Dam.

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