Photo Courtesy of National Corvette Museum

Crews formulate a plan to recover eight classic American sports cars that fell into a massive sinkhole that opened up on Feb. 12 under the showroom floor at the Corvette Museum.

The Corvette Museum, where eight collector cars were swallowed suddenly by a sinkhole, now has another large hole—this time in the side of the atrium housing the cars, so a crane can go in and retrieve the vehicles.

Construction, engineering and geological experts have been at the Bowling Green, Ky., facility since the Feb. 12 incident, examining the building and the sinkhole, which is now said to reach 60 ft to 70 ft wide and about 60 ft deep.

The recovery team will stabilize the building; remove the cars, two of which are covered by dirt in the pit; refill the chasm and repair the floor, a 40-ft-dia section of which fell as the sinkhole opened up, leaving electrical and communication wires dangling over the hole. "The good news is the building is in good condition—the building foundation, the structure," said Mike Murphy, CEO of Scott, Murphy & Daniel LLC, the local construction manager and the company that built the museum in 2004.

"We live with underground cave systems. In our business, we run across this on a monthly basis," Murphy said at a news conference. "We're 25 miles from Mammoth Cave. It's a karst area."

Stabilization of the circular 12-story atrium, a separate structure that merely attaches to the rest of the museum, is scheduled to be completed in early March. The entire job is planned for completion in mid-August.

Each week, repair crews have been working five 10-hour days and eight-hour Saturdays, according to Wendell Strode, museum executive director.

"The sinkhole happened within the parameter of the building," Murphy said. "The foundation systems are such that, while we are in repairs, we will secure those so if [another] sinkhole happens— even outside of here—it will not affect the structure again."

Workers have removed four panels and part of a supporting I-beam from the exterior wall and built a "bridge" that levels the interior and exterior areas and allows the crane to enter.

Parts of the atrium floor have been cut out so that reinforcing concrete can be added. Also, a raised, circular pedestal for a 1983 'Vette has been removed.

Views of the site from a Western Kentucky University drone, which flew over and into the hole, allowed "close-up images of the soil, some of the [collapsed soil] and the concrete above," says Matthew Dettman, WKU professor of civil engineering and an expert in sinkholes.