Swan Quarter Flood Wall
BackgroundSwan Quarter, located in Hyde County, North Carolina has experienced chronic flooding episodes. Hurricanes and tropical storms traveling up the East Coast have flooded the town multiple times, causing almost a billion dollars in damage. The storms damaged physical property and jeopardized the town’s long term economic viability by compromising the local agriculture industry. The town was in need of a solution that would protect 2,400 acres against flood damage.
Project ScopeThe project, which created a 17.7 mile long dike, was completed over several phases. The first series included the construction of a 6 foot high flood wall composed of synthetic sheet piling and composite round pilings were chosen over traditional materials because they offer a much longer service life than steel or concrete. ShoreGuard sheet piling met all of the stringent specifications and provided proven performance in flood wall applications. ShoreGuard uses the most advanced technology of any vinyl sheet piling. The XCR Technology provides industry leading protection against UV degradation and enhanced chemical resistance. To meet the necessary strength requirements the design also featured two horizontal aluminum wales as well as a structural aluminum cap. CMI’s ArmorWare wales and cap met the engineer’s specifications of strength and corrosion resistance as well as provided the community with color options.
PerformanceThe NRCS is tasked with protecting the economic wellbeing of productive agricultural land. Hyde County is one of North Carolinas largest and 65% of its land is used for farming and agriculture. The county, which is elevated only a few feet above sea level is vulnerable to storms and wind tides. The community now has an additional 8 feet of flood protection from dikes, flood gates, drainage canal and flood walls. The additional protection reduces potential flood damages for 120 homes and businesses, decreases utility and community service disruptions and protects farmland from being contaminated by saltwater. In August of 2011, 90 MPH Hurricane Irene moved through the Swan Quarter area. All the residents of Hyde County were asked to evacuate in preparation of this dangerous
ConstructionFor the 6 foot exposed height flood wall, engineers specified 24 foot long sheet piling with 16 feet driven into the ground. The site’s soil boring reports indicated moderate blow counts and conditions ranging from cohesive heavy clays to sandy loamy clays. During the driving they also encountered various debris. The contractor chose to use CMI’s patented installation equipment, the PileClaw Mandrel to assist the driving of the 24 inch wide box profile sheets. CMI’s PileClaw Mandrel was attached to a 50 ton crane to drive the sheet pile. As the project progressed, the crew was setting up and driving each panel 16 feet into the ground in less than eight minutes. ShoreGuard 425 brown panels were chosen for this project to match the natural surroundings. Coordinating bronze ArmorWare Cap and Wales were chosen to add additional strength and rigidity to the flood wall. Composite fiberglass pipe piles were driven every 4 feet and tied into the wall. CMI UltraComposite round piles are offered in multiple diameters and wall thickness and are driven with conventional driving equipment such as vibratory and drop hammers. These piles are the only composite pipe piles in the world that are manufactured in an ISO 9001:2008 production facility and are pultruded to maximize impact strength for increased drivability.
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