CHARLESTON, SC (AP) Plans to blast the spans of the old twin Cooper River bridges across Charleston’s shipping channel have been scuttled. Instead the spans will be lowered mechanically onto barges to be removed.

Previous blasts which demolished sections of the bridges over Town Creek, the channel between Charleston and Drum Island had mixed results.

In October, when a span of the Silas Pearman across Town Creek was dropped into the water, the explosives did not break the steel into sections as planned. A cleanup expected to take only a day lasted almost three weeks.

The Pearman and the parallel Grace Memorial Bridge linking Charleston and Mount Pleasant closed last July after the $632 million Ravenel Bridge opened. The Ravenel is the longest cable-stayed bridge on the continent.

The demolition contractor, the Jay Cashman/Testa Corp. Joint Venture has hired another firm to lower the spans. Mammoet, a firm from the Netherlands with expertise in such work, will handle that portion of the work.

The contractor will pay the added cost of using the other company, said James Law, a spokesman for the state Transportation Department.

No date has been set, but Law said the span of the Pearman Bridge, built in the 1960s, will be lowered first. The Grace Bridge, a narrow two-lane bridge, was built in 1929.

The superstructures can be lowered at 40 ft. per hour and that would mean the work could be done and the channel closed for only about 12 hours, Law said.

Before the $60 million demolition project began, it was agreed the shipping channel should be closed no more than 24 hours. There are penalties in the contract if the channel is closed longer.

The new plan was quickly approved by the Coast Guard.

“I expected the DOT and the contractor all along to submit something worthy of approval,” said Coast Guard Capt. John Cameron. “The usage of the channel is significant.”

The State Ports Authority will work with the contractor to set dates for lowering the spans, said authority spokesman Byron Miller.

Law said explosives will still be used to bring down remaining sections of the bridges away from the shipping channel. There will be as many as six more blasts although no dates have been set.

Today's top stories

Growing Interest in Construction Careers Among Younger People Means Jobs Filled, Deadlines Met

Larry Young Paving Tackles Grade-Separated Interchange in Texas

Caltrans, Crews Working to Repair Highway Landslides

FIRSTGREEN Industries Launches ROCKEAT Electric Skid Steer Loader

'Tiltrotator Effect' Increases as Energy Consumption Goes Down

VIDEO: Birmingham, Ala., Awarded $14.5M Fed Grant to Revitalize Its 'Black Main Street'

Pettibone Celebrates 75th Anniversary of Cary-Lift

Fay Preps Way for Pittsburgh International Airport Modernization Project