On April 29, a sinkhole measuring nearly 600 sq ft opened up on one of the busiest thoroughfares in downtown New Orleans.
Mark Jernigan, director of the New Orleans Department of Public Works, says the city awarded an emergency repair contract last week to Hard Rock Construction in what is estimated to be a $5 million, six-month job. The work will entail repairing and reinforcing collapsed walls of an underground tunnel, backfilling the space and resurfacing the damaged sections of Canal Street.
"We're working to implement a creative engineering solution to a complex problem under emergency conditions. It's very unique to find a tunnel in the middle of downtown New Orleans, especially one with temporary end walls," says Jernigan.
The 700-ft-long, 98-ft-wide tunnel was constructed in 1966 as part of a plan to run a elevated Riverfront Expressway alongside the French Quarter. After the tunnel was built, the idea was shelved and it sat idle for decades. In the late-1990s, part of the tunnel was converted into underground parking for Harrah's Casino, which now sits on top of it.
In mid-April, inspectors from Harrah's Casino called City Hall after they noticed signs that a tunnel wall had started to deteriorate. The city barricaded the area of roadway above and began inspections before it eventually collapsed.
Jernigan says while the tunnel was constructed from concrete and mostly supported by steel I-beams, the temporary timber end walls were left in place. Decades of deterioration took its toll and a significant rain event in mid-April finally compromised the structure. While repairs are being performed at the site of the collapse, engineers will also survey the rest of the tunnel and the other endwall.
"We're going to do some additional testing and investigation on the Poydras Street side to confirm the extent of the damage and the structural integrity," says Jernigan.
The situation exemplifies the challenges New Orleans faces with its deteriorating infrastructure. The city has an estimated $9.3 billion backlog of work to overhaul the city's crumbling roads and underground pipes. Mayor Mitch Landrieu says an estimated 40% of the city's water is leaking out of its century-old pipes.