The city of Charleston recently spent almost $400,000 to address some of its most notorious spots for "sunny day" flooding.

These include the low-lying stretch of Morrison Drive just south of the Ravenel Bridge; the Wraggborough Homes neighborhood around the East Bay Street Post Office; and the intersection of Wentworth and Barre streets.

Each area has received a new “check valve,” a special device inserted in a drainage pipe or culvert designed to stop high tides from pushing saltwater back through and onto the streets.

Diane Aghapour has lived on Gadsden Street, just a few doors down from Wentworth, since 1989, and she has noticed sunny day flooding — also known as nuisance flooding — grow steadily worse, particularly during the past 15 years.

"It came to the point where we warned people who were visiting to use Beaufain, not Wentworth, because you don't want people driving through it," she said. "We've probably had four to five cars by now that have had rust damage. We have learned our lesson about that."

"We're hoping to get some relief," she added.

Two dozen and counting

Earlier this year, the city installed 17 check valves at assorted locations around Cannon Park and Colonial Lake downtown and West Ashley's South Windemere neighborhood.

Since then, however, it continued to test whether similar valves would work in other spots, said Frank Newham, a senior engineering project manager with the city. During these tests, the city inflates a balloon inside a drainage pipe before a high tide, then checks to see if it stopped water from backing up onto neighboring streets.

The tests are done on days when there's no rain. The check valves don't help streets drain from a heavy rain: They only keep high tides from entering the city. The tests led to seven new valves, and more may be coming soon, Newham said.

The city installed its largest ever check valve, 54 inches in diameter, near Morrison Drive. This week, it placed one almost as large, 48 inches, underneath Beaufain Street. 

"The world-famous Wentworth and Barre street lake will go away, hopefully," Newham said. "That intersection floods at just a normal high tide."

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wentowrth and barre

Flooding at Wentworth and Barre streets often gets so bad that the city closes off the streets, as it did on Sept. 10, 2017. Grace Beahm Alford/Staff/File

How they're built

The city had check valves in place for years, but major flooding since 2015 prompted Newham and City Councilman Mike Seekings to tour the city, examine where water was deepest and take a fresh look at the city’s storm drain infrastructure. That work led to the tests and the push for new check valves.

“The more we put in, the more they seem to work,” Seekings said. “It’s been satisfying because we’ve been able to see some results quickly.”

The work found solid support at City Hall. Mayor John Tecklenburg ran on a vow to examine what minor tweaks can be done to improve the city's storm drains — in addition to support for larger projects.

And they're not just being installed downtown. Several have been put in place in West Ashley's South Windemere neighborhood, and the city is looking at testing in the area near Montclair Street and Ashley Hall Road.

"I think council understands that these valves are a good short-term fix for tidal flooding,” Newham said.

As a 16-member crew worked under Beaufain Street on Thursday morning, Charles Rooke, owner of B&C Land Development Inc., explained that the biggest challenge was the tight timing. Earlier in the week, his crews dug a hole in the street and cut open the top of the concrete culvert. 

But the main work resumed shortly after 6 a.m., a few hours before low tide. Crews had just a few hours to clear muck from the culvert, install the valve, seal it with concrete, and let the concrete cure. The few pumps helped keep the work area dry, but they're no match for a high tide.

Much of that work had occurred by 9 a.m., dead low tide, and Rooke felt good. "It went great," he said.

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Check valve

The check valve, shortly after its installation but before its concrete seal has cured. Robert Behre/Staff

'A Band-Aid'

As the city installs check valves, some residents are preparing, not for sunny day flooding, but major flooding from hurricanes and tropical storms.

Some are elevating their homes. Others are looking at buying temporary flood barriers — sizable structures that they could place around their homes before a big storm hits.

Veronica Goodrich, who lives near Colonial Lake, said several of her neighbors are evaluating the costs and potential benefits.

"These are barriers that are not attached to anything. They’re temporary. You can put them up before the flood and you can take them down after the water recedes,” she said. "I don’t see any other option at this point. ... We’re just like sitting ducks.”

Aghapour said she hopes the check valves help, but the larger problem stems from major flooding from torrential rains and tropical systems.

"The bigger issue we're all working so hard to get our city to prioritize is funding for real relief, funding for building a seawall around Lockwood," she said. "That's going to be the bigger solution. This is kind of a minor little Band-Aid to help us through. We appreciate that — I don't want to appear ungrateful for that — but it is a Band-Aid."

"At least we won't be rusting out so many cars."

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High Tide Flooding

Flooding from high tides can shut down most traffic on Morrison Drive, right, near Sanders Clyde Elementary School, left. Grace Beahm/Staff/File 

Reach Robert Behre at 843-937-5771. Follow him on Twitter @RobertFBehre.