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  • Location: Chincoteague National Wildlife Refuge, Accomack County, Virginia

The Fish and Wildlife Service manages thirteen impoundments covering 2,650 acres to provide fall and winter habitats for waterfowl and a spring stopover habitat for migrating shorebirds. Water control structures are used to manipulate impoundment water levels to meet specific habitat requirements of objective wildlife species. During significant storm events, like Hurricane Sandy, storm surge from the Atlantic Ocean breaches the berms of the impoundments and fills them with salt water. The existing water control structures limit the outflow of saltwater from the storm surges, which negatively affects the freshwater impoundments. The project involved the analysis of the existing water control structures for seven interconnected ponds to determine the drain times during storm events such as Hurricane Sandy.

The proposed water control structures were to provide a 10-day drain time for storm surge events. The tidal fluctuations of the Atlantic Ocean were also considered in the existing and proposed drain times of the water control structures. Hydraulic Engineer responsible for hydraulic analysis utilizing Bentley PondPack for the existing and proposed seven water control structures. The project scope was to increase overall outflow capacity to mitigate adverse saltwater intrusion impacts in the freshwater vegetative communities.

B&N implemented an innovative water control structure design to provide a sufficient weir length and a stop log structure to set the water level needed for the targeted bird species for the winter and summer seasons.

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