Explosives will bring down First Avenue East parking ramp

UPDATE: They're going to use some explosives after all.

On Saturday morning between 7 and 8 a.m., wrecking crews will implode the parking ramp in the 200 block of First Avenue NE to make way for the city's new convention center.

Rob Davis, the city's engineering manager, said Wednesday that the event will be of a falling building, as opposed to one being blown up.

Davis said the explosive charges will be set in such a way that the ramp falls in an easterly direction toward what had been Third Street NE. Vibrations will be monitored at the time of the implosion, he added, though the biggest issue will be the “dust plume” that results from the falling structure, he said.

Davis didn't know if the Iowa Department of Transportation intended to shut down Interstate 380 above and alongside A Avenue NE at the time of the implosion. Davis didn't expect dust to get to the Interstate.

“It's more a rubbernecking concern,” he said. It's likely to be an “interesting thing,” he said, watching the ramp fall while trying to drive.

To make way for the new convention center, the city is demolishing everything in the block between First and A avenues NE and Second and Third streets NE except The Roosevelt apartments. However, explosives will be used only on the First Avenue parking ramp in the demolition, much of which is complete, Davis said.

Craig Hanson, the city's streets maintenance manager, on Wednesday said traffic will be routed from A Avenue NE and First Avenue East near the implosion site on Saturday morning until the parking ramp comes down. The job is expected to be complete in an hour.

Hanson said many city departments, including the Fire Department and the Public Works Department, have studied the plans for the implosion and have signed off on them.

Hanson said he will assign a street sweeper to the downtown late Sunday night to clean up dust in time for the workday Monday.