May 08 2018

Renourishment Project Wraps Up

By Emma Woodham, Staff Writer for The Island Eye News

Great Lakes Dredge and Dock finished pumping nearly 1.5 million cubic yards of sand onto the beaches of Isle of Palms in the latest beach restoration at the end of March, wrapping a project that was more than a year in the planning.

Ten years have passed since such a large renourishment project was undertaken by the City, and the island has seen several significant hurricanes since 2008 including Joaquin, Matthew, and Irma just last year.

“The beach is our number one asset. It’s why we all live here, and it is why tourism dollars come in. If we don’t have a beach, we have nothing,” Mayor Jimmy Carroll said.

Coastal Science and Engineering, consultants for the City, began developing the project almost a year and a half ago. In February 2017, the city began to seek funding for the project. Ultimately, Isle of Palms was awarded grants from the South Carolina Department of Parks, Recreation, & Tourism and FEMA, and some funding was provided by the owners of Wild Dunes and its residents. Mayor Carroll explained that the residents of the island outside the resort did not foot any of the bill for the project.

“The cost was not paid by the residents of Isle of Palms. The dredging took place in Wild Dunes because it was their beach that needed dredging,” the Mayor said.

In July of 2017, the city began seeking bids from companies with the ability to tackle such a large-scale, extensive project. Great Lakes Dredge & Dock Company was ultimately awarded a contract of $11,875,000 to complete a renourishment of the beach on the northern end of the island, inside the Wild Dunes Resort. According to Steve Traynum, Project Manager for Coastal Science and Engineering, only a few companies in the country have ocean-certified dredges capable of handling projects of this scope.

One of the challenges that project planners faced was finding a suitable area to harvest the sand. A location was selected, but it was soon discovered that the area chosen was potentially going to be turned into an offshore historic district. The State Historic Preservation Area believes that this area is the graveyard of many old whaling vessels that were sunk by the Union Army during the Civil War to help in the Charleston Harbor blockade.

“We had to search for a new borrow area, which proved to be challenging due to the inconsistent sediment deposits offshore. Ultimately, we found enough suitable sand to complete the project,” Traynum said.

Great Lakes Dredge began unloading pipe at 53rd Ave. only a couple of days after Christmas. Over the next few days, the Dredge Illinois made its way down the East Coast from Virginia and docked in the Charleston Harbor around the beginning of 2018. In January, the city also received an amended SCDHEC permit that increased the maximum nourishment area in the project area, primarily due to the damage that the island sustained from Hurricane Irma.

On January 16, Great Lakes Dredge began working on the project. Dredge Illinois is a cutterhead-suction dredge whose cutterhead digs into the sand. It then sucks sand and water through a pipe behind the cutterhead, through a pre-laid pipe that runs along the ocean floor until it reaches the beach. As the sand built up on the shoreline, bulldozers were used to shape the berm according to the design. More sections of pipe were added as the project moved along the beach.

Throughout the project, Dredge Illinois had to return to the Charleston Harbor a couple of times for some minor repairs, but this phase of the project never met with any significant delays. In less than a month, Great Lakes Dredge delivered over 600,000 cubic yards of sand to the beach.

In late February, the project experienced some difficulty with mud rollers. These develop when a layer of soft mud builds up in the dredge pipe, and is deposited onto the beach. If mud rollers end up in the surf area, they can erode and wash away. In an effort to prevent more of these, Great Lakes Dredge moved their dredge away from that area. Crews on the beach also worked to remove the mud rollers that remained on the beach.

The project wrapped up on March 26, and Great Lakes Dredge quickly began to demobilize their equipment. The final step was tilling the areas of the beach that were recently nourished, being sure to leave the sand loose enough for turtles who may begin nesting in the coming months. Now that the sand has been placed, Traynum says it will take several months for the beach to adjust. He also added that the berm may overwash during unusually high tides or storm events, which may cause some ponding on the berm. However, it will create a more natural looking beach in the long run.

“The slope of the intertidal beach will change based on wave climate. Wind-blown sand will accumulate along the dune line and over time, dune vegetation will emerge along the berm,” Traynum said.

Because it has been a decade since the last major renourishment project, Mayor Carroll hopes that the beaches will last another ten years or longer. He realizes that the island will have to continue renourishing the beaches in the years to come but says that the city will have to wait and see what Mother Nature brings.

“It is the beach that draws in tourists, along with the history of Charleston. It is the beach that draws the crowds. If you build it, they will come. If you don’t have it, they won’t come,” Mayor Carroll said.

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