ST. PETERSBURG - A walking tower crane high enough to require clearance from the FAA will soon be a fixture right downtown on Second Street S. It will lift 60-foot-long steel trusses, concrete planks, portable toilets, even trailers.
They will be hoisted to the top of McNulty Garage, where 85 loft-style condominiums will be built. The McNulty Lofts are already almost sold out; their prices ranged from less than $200,000 to nearly $600,000.
When construction cranks up, it will be one of the more unusual building projects downtown.
For a start, the six-story complex will be built on top of a seven-story garage, meaning the work begins 87 feet in the air. On the ground around the garage are busy downtown streets, limiting construction room even more.
"There are a couple of challenges on this project," said Pate Clements, general contractor with the Murray Co., which is building the lofts. The project is being done by a subsidiary of Echelon Real Estate LLC.
"We will have limited work space on the ground," Clements said. "The sheer height, getting all that material from the ground to the elevation" will require the crane, which has an arm going straight up that is 200 feet high, and then it bends and another portion is 120 feet long.
It is tall enough that Federal Aviation Administration clearance was needed, and it will be marked with a light and a flag. The crane is being built specifically for this job. At 31 feet wide and 45 feet long, it is as long as a tractor-trailer and three times as wide, Clements said.
"We will have all the storage trailers, mechanical and electrical, underneath on the bottom level of the parking garage," Clements said. "The crane, at different times, will lift the trailers up to the level we are working on.
"We will get everything up there. Usually it would sit on the ground (around a development) for the duration of the project. We won't have enough room for that."
Also, all the subcontractors usually on a project at the same time won't be able to be up top together because there is too little room. They will "be from 14 to 15 sub categories," of workers that need to be on top of the garage, Clements said. These include steel erectors, concrete pourers, precast beam handlers, tile layers, plumbers, masons, carpet layers, painters, electricians and glazers. The crane will lift them and their equipment up as they are scheduled.
This won't be the first vertical expansion for Murray Co. of Clearwater. It added one to the Columbia Largo Medical Center. Clements said vertical add-ons are not regular but getting more frequent.
"As the ground gets more and more costly, it becomes more and more prudent to think vertical."
Builders will start the McNulty Lofts project by chipping away at the concrete posts on top of the garage. They will be looking for the couplers placed there when the garage was finished in 1998. In anticipation of adding on later, the garage was strengthened and prepared when it was built.
Reinforced steel bars bent into cages will be threaded into each of the couplers and 8-foot concrete posts poured around them. These posts will become the supports for the ground floor of the lofts. Once the concrete is poured, it takes seven days to cure.
To test the posts, a sample of the concrete is taken from each batch used. Out of the samples, 24-inch-high and 8-inch-round cylinders are made and taken to a laboratory where they are checked for strength with a hydraulic press.
"The pressure gets greater and greater. When it crushes (the cylinder), it gives the lab a reading," Clements said of how much weight each post can hold. The requirement for McNulty Lofts is 4,000 pounds per square inch of concrete.
Once the posts have cured, steel beams are set between the columns and then covered with precast hollow core concrete planks. The steel beams are laid in one direction and the planks in the cross direction.
When the precast planks and steel trusses are needed, they will arrive by the truckload.
"We don't have any staging area. So we will have just-in-time delivery for each component," said Clements.
For the trusses, that means a lot of trucks. Each floor requires nine trusses. Each truss arrives in two pieces; otherwise it would be too big to move. For one floor, that means 18 trailers, Clements said.
The trusses are being made in St. Petersburg.
"Every single subcontractor, with the exception of the crane, is a local subcontractor," Clements said. "The construction dollars are staying here in the community."
Murray will have five to seven people on the job per day, but trades people will total between 150 and 200.
"It will be a couple of hundred additional people per day down here eating lunch, buying parking," Clements said.
On the street level of the garage is Midtown Sundries, a popular restaurant that plans to stay open during construction, as will four floors of the garage.
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