ConsCom Hears About Shoaling Control Structure, Which Town Officials Hope To Never Build

CHATHAM – Thanks to shifting sands, the shoaling that has clogged the Stage Harbor entrance channel has slowed somewhat in recent months. But town officials have a plan to install a groin and a series of vanes made of sheet pilings that aim to deflect some of the sand moving south of Morris Island, rebuilding Crescent Beach. It’s an ambitious, creative, expensive structure that town officials hope they never have to build.

 It’s “a unique and unusual project, but I think it’s also safe to say we have a unique and unusual situation,” Coastal Resources Director Ted Keon told the conservation commission on Oct. 23. The most recent changes in the barrier beach resulted in a new inlet near Morris Island in 2017, the so-called Fools Cut, and the mostly east-to-west current through that inlet caused large shoals to migrate west, choking off the Stage Harbor entrance channel. The fast-moving water also scoured away Crescent Beach, the largely manmade spit that protects the harbor east of the channel, thinning the beach and raising fears of a washover.

 “We do not want that to breach. That would not be a good scenario,” Keon said. A break in the beach could essentially reopen the harbor’s original inlet, which was filled and moved to its current location by the Army Corps of Engineers in the late 1960s, according to documentation filed with the conservation commission.

 Working with consultant John Ramsey of Sustainable Coastal Solutions, the town has developed a plan to install a 640-foot-long temporary structure made of vertical sheet piles like the ones used for harbor bulkheads. The structure would extend southwest from the beach to form a continuous groin and would then zig-zag to the southeast in a series of 11 separate vanes. The goal is to redirect sand so that it nourishes Crescent Beach rather than simply flowing west to clog the channel.

 While Keon said the approach is a reasonable one, “I’m going to be very upfront and forward that I hope we never have to build this.” The vanes would require extensive permitting, would cost an estimated $7 million, and would be somewhat unsightly, requiring warning lights to keep boaters away.

 “This project isn’t going to be needed forever,” Ramsey said. Based on the predicted cycles of the barrier beach, the Fools Cut should eventually fill in as North Beach migrates south, slowing and then stopping the flow of sand. When that happens, the sheet piles would be removed the same way they were installed, using a machine that vibrates the corrugated steel to move it through the sand.

 “What we’re proposing is actually relatively small compared to what they did back in the ‘60s,” Ramsey said. The Army Corps relocated the harbor inlet and then installed wooden pilings to try and steer sand away. When this project is complete, all materials will be removed from the area, he said. “We’re not intending to cut anything off and leave it in place, like the Army Corps did with their wood piles,” Ramsey said.

 In recent years, a large shoal has established itself on the southwest corner of Morris Island, naturally deflecting the current away from Crescent Beach. That development is a hopeful one, he said.

 “The erosion of Crescent Beach has slowed, which is great. But again, it’s not repairing itself — it’s not growing,” Ramsey said. 

 Keon said the town wants to have the vane project ready to implement, should it become necessary.

 “We don’t want the changes that are happening out there to progress to the point where we need to do this, and then we don’t have approvals in place in order to implement something,” he said. “This is really preparing the town for the future.”

 The planned structure would involve sheet piles that extend a couple of feet above the water, with navigation lighting and warning signs to keep boats away. 

 “This is not going to be the prettiest structure, if constructed,” Ramsey noted.

 The multi-million-dollar cost is also something that the town is not eager to take on, Keon said.

 “The cost of this is not small, but the cost of our dredging program is not small either,” he said. At the peak of the shoaling, the county and federal dredges were clearing the harbor channel frequently — at taxpayer expense — and navigational access was still tricky at times.

 The unique proposal certainly poses a number of questions for the conservation commission, which generally opposes the use of manmade structures to control erosion. It’s also challenging that the project lacks a certain start or end date; it also proposes building the vanes within a pre-identified zone off Crescent Beach, but no specific location has been identified yet.

 “You’re asking for a little bit of a blank check, depending on how conditions change, and we like specificity,” commissioner Janet Williams said.

 The conservation commission continued its review until Dec. 4.