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Jekyll Creek Dredging Begins March 18

Corps to use new techniques to manage dredge sediments.

Tyler Jones - CRD Communications Specialist | March 10, 2019

A contractor for the U.S. Army Corps of Engineers is set to begin dredging Jekyll Creek north of Downing Musgrove Causeway to the St. Simons Sound on March 18.

Cottrell Contracting, of Chesapeake, Va., will remove about 200,000 cubic yards of sediment from the eastern 75 feet of the channel, which is part of the Atlantic Intracoastal Waterway. Crews are slated to arrive on scene on Monday, March 11.

The corps and other groups have had long-standing navigational concerns over the Jekyll Creek portion of the Atlantic Intracoastal Waterway. It is the shallowest point in more than 160 miles of Georgia’s portion of the waterway. Jekyll Creek has not been dredged since 1998, and its sediments are fine-grain with very low sand content, often called “pluff mud.”

The aim of this pilot project is to develop economically efficient and environmentally acceptable methods of managing dredge material. This $6 million, federally funded project will bring the channel’s depth to 10 feet and is expected to be complete April 27. Undoubtedly, there will be changes to the schedule during this project, based on weather and other unforeseen conditions. The website at https://coastagadnr.org/jekyllcreek will be updated as changes occur.

The removed sediment will be placed in two locations using new methods meant to keep Georgia’s sediments in the coastal system and help keep marshes healthy.

The first sediment-placement location is north of Jekyll Creek in the St. Simons Sound, about 800 feet south of the St. Simons Pier. This location, commonly called the “Deep Hole,” is naturally deeper than surrounding areas in the sound and is between 60 and 80 feet deep. For comparison, other areas in the channel are dredged to about 38 feet deep. About 97 percent of the dredged sediment will be placed in the Deep Hole, where tides naturally spread materials. This sediment will be deposited by pipe near the bottom of the Deep Hole, about 5 feet from the sea floor. Commercial and recreational traffic through the sound will not be impacted by this sediment placement. Scientists with the Jacksonville, Fla. based firm LG2 Environmental Solutions will monitor the movement of the placed sediment for up to two years.

The remaining dredge sediments will be placed on nearby marsh using a spray technique new to Georgia known as “rainbowing.” About 5,000 cubic yards of sediment is scheduled to be pumped onto the marsh north of the Jekyll Island Airport from April 20 to April 25. This area of marsh has a lower elevation, which makes it susceptible to saltwater inundation as sea level rises. The sediments will be sprayed into the marsh onto a 5-acre area in a thin layer surrounded by coconut-fiber containment logs. The goal of spraying dredge sediments into this area is to raise the elevation 1 to 2 inches in some places and up to 1 foot in others, allowing new marsh grass to grow atop it at higher elevations. Another 5-acre location to the north will act as a control area for the project. Scientists from Georgia Southern University and the University of South Carolina will monitor the placement and control areas for a two-year period to see how the thin-layer placement of sediments affected the marsh. The corps has had previous successes with thin-layer placement in New Jersey, Maryland and Louisiana.

These techniques are part of a “beneficial use of sediments” pilot project and have never been performed in Georgia. The primary goal of the project partners is to proactively explore whether these techniques can be used in the future to build a more resilient Georgia coast.

In designing this pilot strategy, the corps’ Jacksonville and Savannah districts worked with the corps’ Regional Sediment Management Center of Expertise, as well as other federal, state and nonprofit agencies. The Georgia Department of Natural Resources’ Coastal Resources Division (CRD), the Jekyll Island Authority (JIA), the environmental nonprofit The Nature Conservancy, the National Oceanographic and Atmospheric Administration (NOAA), the U.S. Fish and Wildlife Service and the U.S. Environmental Protection Agency (EPA) were all involved in developing the pilot strategy. Planning began in 2016 with a visit to the site by the corps’ South Atlantic Division commander. In subsequent months, the Corps held stakeholder meetings and public hearings while coordinating with CRD and JIA.

CRD conducted side-scan sonar and water quality surveys of the deep hole site in June 2017 with additional surveys at both material placement sites in October through December of 2017. CRD also helped coordinate imagery and elevation data at the thin-layer placement site.

JIA and The Nature Conservancy purchased an elevated monitoring camera system to provide imagery of the project as it progresses. The public will be able to access this camera’s feed after dredging begins. For more information, please call CRD at (912) 262-3140.

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