Charleston roads buckle and crack as ground beneath settles - The Post and Courier

Charleston roads buckle and crack as ground beneath settles | SC Climate and Environment News | postandcourier.com

For about 350 years, Charleston's peninsula has expanded outward, pushing against the natural boundaries of the harbor, the Ashley and the Cooper rivers.

From Union Pier in the east to Lockwood Drive in the west, and from Magnolia Cemetery in the north to White Point Gardens in the south, roughly half of the modern-day peninsula is built on some form of "reclaimed" land.

Now that artificially made ground is sinking, causing roads across the city's historic peninsula to warp and distort — and there's no "one-size-fits-all" solution to the problem.

"The quick thing to do is resurface it, which is great because it smooths it out," said Christina Butler, author of "Lowcountry at High Tide: A History of Flooding, Drainage, and Reclamation in Charleston, South Carolina." "But every time you put another layer of concrete or asphalt down, you're adding weight, which is going to make the road settle even faster."

Land reclamation is a misleading name, as the process doesn't "reclaim" anything. It pushes out the physical borders of a landmass using landfill. As the debris beneath compacts over time, that ground starts to settle and sink.

The rate of sinking depends on the landfill type, which comes in a variety of different forms depending on the era, Butler said.

A more recent example would be the Hagood dump, a mid-20th century project on the peninsula's west side that would later form the foundation for much of the area west of Hagood Avenue. Butler said most of the foundation for that part of the peninsula is sanitary garbage without organic materials that can rot and decompose. Today, Hagood Avenue is infamous for potholes and its rough condition, and it's vulnerable to tidal flooding on sunny days and stormwater flooding on rainy days.

The road connecting Brittlebank Park crumbles on the sides as the earth sinks beneath it, Wednesday, June 26, 2024, in Charleston. Broad swaths of the peninsula were built on artificial land. Now that ground is sinking, and roads across Charleston are buckling and cracking as a result.

"Traveling along Hagood Avenue today with its frequent flooding, scarce sidewalks and unwelcoming street design is rarely a pleasant experience," a 2023 report from Charleston's Design Division bluntly noted. "It’s a route taken by those that absolutely have to, which is often Medical District commuters and neighborhood residents."

Under former Mayor John Tecklenburg, the city was planning a substantial overhaul of Hagood Avenue which would have included efforts to address flooding and elevate the road. A city spokesperson said plans to improve that part of the peninsula are still in the works, with further details likely coming later this year.

The city of Charleston landfill off Hagood Avenue and Fishburne Street in the marsh of the Ashley River, from 1964. The landfill destroyed the naturally occurring Gadsden Creek.

Fishburne Street and Lockwood Drive, which also sit on top of the Hagood Dump, are also sinking.

"The field at Joe Riley Park, in the years since it's been built, they've had to redo that whole field because of the sinking action that's happened there," said Tom O'Brien, Charleston's director of public service. "The stabilization of unstable ground is just a really difficult situation to deal with."

The West Side isn't the only area that's sinking. Grace Bridge Street, located on the East Side near the Cigar Factory, is another road built on landfilled ground.

"The kids love to bike on it because it's like a little mini roller coaster," Butler said. "That area was filled with a lot of organics, and then some of the later filling was that sanitary fill. It has settled so much that it looks like little ocean waves."

The sidewalk has formed into wave-like ridges on Grace Bridge Street, Wednesday, June 26, 2024, in Charleston. Broad swaths of the peninsula were built on artificial land. Now that ground is sinking, and roads across Charleston are buckling and cracking as a result.

Sinking roads can cause more than just potholes. As the ground sinks, sewage infrastructure pops up above the ground. Buttressed by infrastructure underneath, it's going down at a slower rate than the heavy asphalt around it.

"It's basically like hitting a boulder when you're driving, if you're not paying attention," Butler said.

Charleston isn't the only city built upon mountains of garbage. Other coastal cities such as New York, Boston and Newport also artificially extended their boundaries using similar processes. But Charleston's marshy ground makes it somewhat unique and a bit more vulnerable, Butler said.

So what's the solution to the Holy City's sinking roads dilemma? The answer is tricky, and no potential solution is easy.

On not-so-solid ground

Many of the peninsula's roads — including major thoroughfares like Hagood Avenue, Morrison Drive, East Bay, Meeting and Calhoun streets — are administered and managed by the South Carolina Department of Transportation.

Rob Perry, DOT's deputy secretary for engineering, said it's possible to rebuild and reinforce roads in marshy and soft-grounded landfill areas. But it can be a disruptive and expensive process.

"You'd probably have to close and detour," he said. "That would be one of those things that would be a long-term closure."

Large pockets of water often collect after rain on Hagood Avenue, Wednesday, June 26, 2024, in Charleston. Broad swaths of the peninsula were built on artificial land. Now that ground is sinking, and roads across Charleston are buckling and cracking as a result.

Perry said the department takes a data-driven approach to determining how to spend its annual resurfacing allocation. The department sends out teams to scan the surfaces and sub-surfaces of its roads, and then uses that to inform a list of routes with the greatest need. This year, the department has $719 million in the pot, which needs to cover everything from interstates to "secondary routes" like Hagood Avenue.

No peninsula roads are on the schedule for 2025, but the department is planning a resurfacing project on Spruill Avenue in North Charleston, which doubles as State Road 32.

Butler floated other potential infrastructure ideas. She noted that builders are increasingly turning to a product called "thirsty concrete." It's a porous and lighter material that supposedly can withstand the weight of heavy traffic. It also allows water to pass through the material, limiting pooling and stormwater flooding.

Gravel roads might be another solution in the same vein, but that solution comes with caveats. It could kick up dirt. It would force people to drive slower. Although, Butler noted, that second detail might actually be a net benefit.

Potholes litter the road where Fishburne Street and Lockwood Drive intersect, Wednesday, June 26, 2024, in Charleston. Broad swaths of the peninsula were built on artificial land. Now that ground is sinking, and roads across Charleston are buckling and cracking as a result.

"No one needs to be going that fast through neighborhoods that flood, anyway," she said. "As a downtown resident who cycles, I would love people to be going a little bit slower and the floodwater to go more quickly."

As roads around Charleston sink, they could also become more vulnerable to flooding. Ocean levels around the city are set to rise by roughly a foot over the next 25 years, according to the National Oceanic and Atmospheric Administration.