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Posted 7/11/2011

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By Sean McBride
Charleston District Public Affairs


Fort Sumter. The Morris Island Lighthouse. The USS Yorktown.

What do these three things have in common? They are all listed in the National Register of Historic Places and have all have received involvement from the Charleston District. The Corps of Engineers constructed Fort Sumter prior to the start of the Civil War. In 2008, the Charleston District completed an erosion-control project at the Morris Island Lighthouse to protect its foundation. Now, the District has completed a concept study on options for protecting the USS Yorktown to extend its life into the future.

The Patriots Point Development Authority (PPDA) requested planning assistance from the Charleston District to study the different options of constructing a cofferdam around, and making repairs to, the 68-year-old World War II era vessel. A cofferdam is an enclosure constructed in water to provide a barrier and allow for a dry work environment within the structure.

In the Water Resources Development Act of 1974, Congress authorized the Corps of Engineers to assist the states in preparation of plans for the development, utilization and conservation of water and related land. Using this authorization, the Charleston District agreed to a 50-50 cost-share of the study to assist the PPDA in completing an analysis of the alternatives for various types of cofferdams in order to complete crucial repairs to the aging vessel.

Three types of cofferdams were considered: portable, temporary and permanent. A portable cofferdam is best suited for small repairs on a structure, as it can be moved and reused. A temporary cofferdam is constructed around the structure and is used for larger repairs, but can only be left in place for up to a year while undergoing repairs. A permanent cofferdam is best suited for long-term repairs and protection of the structure and lasts for approximately 25 years.

In the case of the USS Yorktown, a permanent cofferdam would allow for lighting of the ship’s hull as well as public and boat access to see around the ship. This could add an additional aspect to the many daily tours given on the ship and provide a unique sight at night if the ship were lit up.

The PPDA board of directors will ultimately decide which alternative they will use.

“Through the study, we were trying our best to offer the sponsor a range of possible options for the work that needed to be done,” said Dudley Patrick, project manager. “We’re providing solutions for the survivability of the USS Yorktown for future generations.”

Cofferdams are currently being utilized for other historic ships on the coast as well. For instance, the USS North Carolina, docked in Wilmington, NC, is currently utilizing a portable cofferdam while the USS Alabama, docked in Mobile Bay, AL has recently seen construction on a permanent cofferdam around the ship.

The USS Yorktown, one of only 2,430 remaining National Historic Landmarks in the US, has been a staple for tourists to the Lowcountry since 1975. Its iconic location on Patriots Point in the heart of Charleston Harbor serves many tourists each day looking to learn educational and historical information. Using a cofferdam system to make repairs to the hull of the Yorktown would enable the vessel to be preserved for many years to come.

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