Working on the AIWW

Published Oct. 9, 2019
AIWW Dredging

The Charleston District is currently dredging the Atlantic Intracoastal Waterway in several places. Some of these area's haven't been dredged in 10 years. Learn about the dredging plan and how it will help.

If you’re enjoying your summer boating on the Atlantic Intracoastal Waterway in Charleston (obviously while wearing your life jacket), you might have noticed a large machine with a lot of pipes trailing behind it. Or maybe you saw bulldozers pushing dirt around to make big piles. The Charleston District has had a lot of work going on in the AIWW lately.

“The Corps has the authority to maintain the Atlantic Intracoastal Waterway,” said Jeremy Johnson, project manager. “As part of that, we not only dredge the waterway to its authorized depth, but we also maintain placement areas for the dredged material we remove.”

A cutterhead dredge recently removed 500,000 cubic yards of material from the bottom of the federal channel at Breach Inlet to restore that stretch of the AIWW to its authorized depth of 12 feet. This section is part of $9.4 million in supplemental hurricane disaster funding to remove approximately 1.5 million cubic yards of material from high shoaling areas between Charleston and Georgetown. Many of these sections haven’t been dredged in 10 years. The Breach Inlet dredging was completed at the end of July and the entire project should be completed by the end of the year.

The material was pumped into the placement areas between the Isle of Palms and Sullivan’s Island that had just been prepared. The perimeter dike walls were raised in three placement areas to create additional capacity for this project and what would be pumped in from future projects. Crews first raised the dikes in one area so that the dredging project could begin, then continued in the other two areas while the dredging project happened. This $3.5 million project was completed in May.

“We haven’t seen this amount of work on the AIWW in the previous 10 years,” said Johnson. “The District is proud to be able to keep the channel at a depth to allow for commercial and recreational boaters to pass through without issue.”

The dredging cycle consists of four parts: dredging, drying, ditching and diking. Material, like that from Breach Inlet, is pumped into a placement area where it is then left to dry out. Backhoes then come in to create ditches in the material to allow remaining water trapped inside to drain out. 

Finally, bulldozers move dried material and compact it on existing dikes, raising the elevation of the perimeter of the placement area.  This creates capacity for future pumping of material into placement areas, ensuring that the dredging cycle can continue into the future.