COASTAL OBSERVER

To keep pace with rising sea level, a drainage plan for Pawleys Island calls for raising the roads – 6 inches at a time over the next 15 years. Coupled with maintenance and new infrastructure, that’s a $31 million undertaking at today’s prices and nearly 50 percent more with inflation factored in.

And that’s only the start.

A package of projects is still being compiled that will extend over the following 35 years to rebuild and expand drainage infrastructure.

“We’re talking new pipes, new inlets to capture areas that are currently under-served, expanding existing systems,” said Aaron Akin, water resources project manager at the engineering firm SeamonWhiteside.

When Akin and his colleague Ryne Phillips present the final draft to Town Council next month, it will include the cost estimates and a plan for funding the work.

The firm started work in 2024 on the drainage master plan. After surveying the existing infrastructure, the engineers created a computer model that predict the level of flooding under various combinations of tides, rain storms and rising seas over 50 years.

“As you know, a lot of the drainage structure here is very old,” Akin told the council last week. “A lot of it is just not designed to handle a lot of today’s events.”

Some of couldn’t be found since it is either under water or buried in the marsh along Pawleys Creek.

Over the summer, the engineers proposed a pilot project that would create a berm along the creek side of Myrtle Avenue near the Pawleys Island Chapel. As the master plan was refined, that project became less of a forerunner and more of an outlier, said Town Administrator Dan Newquist.

The town received $250,000 in the state’s 2023 budget for drainage work, and that money has yet to be spent. The goal is still to apply that to a pilot project, Newquist said.

“We don’t want to ask for another extension,” he said.

It makes sense for the town to adapt the streets to serve as perimeter defenses against rising water, Akin said. “The roadway along the marsh is one of the lowest areas on the entire island, and that’s where you critical infrastructure is. That’s your emergency access. That’s a huge safety issue.”

The typical tide today rises 3.5 feet above sea level. More than a quarter of the island’s roads are at  or below 4 feet in elevation.

The extreme high tides rise about 5.25 feet, higher than most of the island’s roads.

“You have about 80 percent of your roadways at risk of being overtopped at least one or two times a year, with a very large percentage – probably about 20 percent – at risk of being overtopped on any given day,” Akin said.

The extreme tides that reach 5.25 feet a couple of times a year now will occur every other day 50 years from now if projections are correct, he added.

The work is intended to deal with the extreme tides and nor’easters, but not major storms.

“If a new Hugo comes through, leave town,” Akin said, referring to the 1989 hurricane.

The first phase of the proposed work  would raise portions of Myrtle Avenue to 4 feet with additional asphalt. Going higher will require going wider, Akin said, so the right-of-way along the creek will also rise.

That would be coupled with  a cleanout of drainage systems and their outfalls and the installation of devices to keep the tide from flowing into the drains. That would ensure that the elevated roads don’t trap stormwater on the landward side, Akin said.

The cost of that phase is estimated at $5.7 million today and $6.5 million in another two and a half years. The town will receive $2 million from the capital project sales tax passed by Georgetown County voters last year.

Phillips said the best way to use that money is to leverage grants or other outside funding. 

“We have a story to tell,” he told the council. “The grant isn’t about engineering. It’s about telling a story.”

Some grants can be sought by the town, but with only Newquist and Town Clerk Corey Higdon to do the work, Phillips suggested hiring a firm to handle larger grants.

The master plan envisions three more phases, with another 6 inches added to the road elevations until they are all at 5.5 feet.  After the minimum elevation reaches 4.5 feet, the plan calls for $5.2 million of infrastructure work in the Birds Nest section on the south end, around Town Hall and at the north end of Myrtle Avenue.

Future drainage improvements include underground chambers to store stormwater so it can be released gradually into the ground or creek. Even with those improvements, the plan calls for road elevation to continue to rise until they are 7 feet above sea level in 50 years.

The state Department of Transportation actually owns the roads and drainage structures on the island. No one expects the agency to actually fund the town’s plan, but Akin said it will be important to build on the town’s partnership with DOT. 

“With a lot of the maintenance and cleaning work, they’re going to be able to do it a whole lot cheaper and it’s their drainage so they’re going to be responsible for it,” he said.