How tunnels could surface as threat

By JEFF WILKINSON - jwilkinson@thestate.com

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Two underground drainage tunnels big enough to drive a Thunderbird through are causing design problems for the six-story, $20 million condo and parking garage project in Five Points.

The tunnels, built in 1927, run under the northwest corner of the old Kenny’s Auto Supply lot. They are the main conveyance for storm water in the flood-prone urban village.

The issue is that the city needs access to the tunnels should something go wrong.

Tunnels large enough to walk through converge between Devine and Greene streets in Five Points.

/C. ALUKA BERRY/CABERRY@THESTATE.COM

Link: Five Points interactive feature
TUNNEL Q&A

Q: When were the Five Points tunnels built and why?
A: The tunnels were built in 1927 as drainage tunnels. One stretches, generally, from Palmetto Health Baptist, at Taylor and Sumter streets, to a cavernous junction roughly underneath After Hours Formalwear in Five Points. There, it is joined by a tunnel from Martin Luther King Jr. Park. The two then run in tandem to Maxcy Gregg Park. They are the main storm water conveyance for that huge area.
Q: Have they ever been used for anything else?
A: Amateur urban spelunkers have been sneaking in for years. (We don’t recommend it.) And who knows what has gone on down there through the decades. Historians we spoke to, however, knew of no other “official” use.
Q: If they are so big, why does Five Points flood?
A: It’s not the size of the culverts, but the restricted flow of Rocky Branch Creek from Maxcy Gregg Park south that is the problem. Think of it as a bathtub with an adequate drain, but where the doggone pipe (the creek) is too small.
Q: Are there any other tunnels in Columbia?
A: You betcha. Robert Mills, the United States’ first architect and designer of the Washington Monument, included several tunnels in his design for the Columbia Canal in the early 1820s. The tunnels run under the canal. They channel storm water to the Congaree River, protecting the integrity of the canal levees.
Q: What about the legend of a downtown tunnel from the State House?
A: When the renovations at the State House were completed in 1998, workers swore there were no tunnel entrances. But the legend continues. Supposedly there are entrances in the graveyard of a downtown church, in the Arcade on Main Street and in the basement of a Main Street office building. But the tunnel is still a mystery. If you findit, call us.
— Jeff Wilkinson

Developers say they can work around the tunnels by leaving undeveloped space above them that would accommodate a backhoe.

“We’ve set up our structural design to straddle the culvert,” said Stan Harpe, who is building the project with partner Ron Swinson. “We’ve known that it’s been there since day one, and made sure that our structural guy knew about it.”

But city engineers aren’t sure it will be so simple.

Utilities director John Dooley is weighing myriad scenarios surrounding the drainage tunnels, which run parallel to each other and are 7 feet tall by 14 feet wide and 7 feet tall by 8 feet wide.

The city has to grant an easement to build the structure on top of the tunnels — something that usually doesn’t happen even over a run-of-the-mill sewage line.

For instance, Richland 1 had to redesign its new track complex in Owens Field Park because of a sewage line.

Because of the size of the culverts, repairing them if they fail might require more room than the design allows.

“This is not your typical 12-inch pipe in the ground,” Dooley said. “How do we get in there? We need horizontal clearance as well as vertical clearance. They can bridge the tunnels, but access is the key.”

Also, if the tunnels collapse for some reason, or the soil around them is washed away, the ensuing sink hole could threaten the integrity of the structure, he said.

Former city manager Miles Hadley said one of the tunnels caved in some years ago, collapsing the floor of a children’s dance studio near what is now After Hours Formalwear.

“The building could cause problem for the tunnels, and the tunnels could cause problem for the building,” Dooley said.

The condo project, dubbed 5 Points South, is a dramatic departure for Five Points.

It’s a high-density, mixed-use, three-quarter-block development more reminiscent of Midtown Atlanta or the Fourth Ward in Charlotte.

A Walgreens drug store will anchor the corner of Saluda Avenue and Blossom Street. A bank will be located at Santee and Blossom streets. And space for a restaurant or store will be available mid-block on Devine Street.

More than 200 public parking spaces will be located on the second and third floors of the building — a priority for many Five Points merchants.

Under an agreement still under negotiation between the developers and the city, the public would pay about $6 million to build the two decks.

The city will own the spaces and keep the income, building at a price lower than it could get the spaces for otherwise, Mayor Bob Coble has said.

The top three floors will feature 27 town-house-style condominiums, from 1,400 to 1,800 square feet each.

Parking for residents will be segregated in personal, fourth-story garages. The price of the condos has not been set, Swinson has said, but they will be “high-end.”

Swinson and Harpe’s plan would place interior and exterior parking spaces on top of the tunnels, giving workers easier access if necessary.

City engineers and the developers’ structural engineer are huddling to try to find a compromise that will allow the building to go forward — a light at the end of the tunnel, if you will.

“We’ll have to investigate to see what’s down there,” said Steve Gantt, assistant city manager for operations. “They’ll have to figure out how they can do it.”

Reach Wilkinson at (803) 771-8495.

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