Another Step Forward for Atlantic Station

$2 billion development coming alive with SouthTrust Tower completion

A change in the building's height and a desire to achieve LEED certification were among the hurdles the construction team of Hardin Construction and Smallwood Reynolds Stewart Stewart had to overcome on this first commercial office building for Atlanta's Atlantic Station.

by Scott Judy

Atlanta's $2 billion Atlantic Station development, billed as a "live-work-and-play" destination, took another step toward full realization with the recent completion of its first commercial structure, SouthTrust Tower.

General contractor Hardin Construction of Atlanta was on schedule to deliver the 24-story, $40 million core-and-shell project April 1. Getting to that point involved some fancy footwork by Hardin and project architect Smallwood Reynolds Stewart and Stewart of Atlanta, as the parties juggled significant project changes, including additional floors and a desire to attain LEED certification.

Getting Started

Hardin started work in December 2002. The project required three levels of parking underneath the building, and, at the time, 17 stories above that. Changes came quickly, however.

"As we were coming out of the ground with the foundations, the owner (Atlantic Station LLC) decided it might be a 20- or 21-story building," said Skip Loman, construction manager for Hardin. The construction team redesigned the building's caisson-based foundation system, adding caissons.

The site was a tough one for the foundation contractor, Long Foundation of Tarrant, Ala. The contractor encountered steel slag dumped on the former Atlantic Steel site while drilling the approximately 30 caissons, which ranged from 10 to 40 ft. in depth.

"If they hit the slag we had to cut the slag out," Loman said, adding that this material was then hauled to an EPA- and city-approved site.

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The site wasn't all bad, though. A section of solid bedrock granite also sat beneath the project. When the contractor found these sections, caisson depth was minimal and installation easier.

Still, "Getting the foundations in probably took a month longer than we had anticipated," Loman said. "The cost of dealing with the rock was probably twice of what the original caisson contract was. It was a pretty intensive rock job."

Even as the structure progressed vertically, the owner made changes in the building's height.

"By the time we got to the lobby level they were pretty sure they were going to go at least 20 stories, so we beefed up the structure in the middle of the building, and then they added a 22nd floor - all while we were going up," Loman said. "We were about halfway up the building when they finally decided how many floors it was going to be."

Brian Leary, vice president of design and development at Atlantic Station LLC, said the change in the building's height was a byproduct of the development's popularity.

"Increasing the building's height during construction is a good problem to have," Leary added. "It says that the demand for an Atlantic Station address was greater than even we expected."

With the new height, the building now needed more elevators - a trick considering the core was already designed.

"We had to get two more elevators into the building, within the same sized core," Loman said. "We were able to sneak an extra elevator in the two high-rise banks without actually changing the core."

Accelerating

As the project moved forward, the team continued to feel the impact on the schedule of both the initial delay with foundation work and the building's expansion upward. Though the project had grown in scope, the original 16-month schedule remained fixed.

To make up time, Hardin worked with formwork contractor Southern Pan Services of Lithonia, Ga., and other subs to speed the structural concrete stage to a rate of one floor every five days. Mostly, Loman said, "It was just a lot of overtime."

There was actually more to it than that. The concrete contractors used a concrete mix that would reach specified strengths within 24 hours, and then staged crews through roughly 15-hour days.

"We would start a pour at 2 a.m. and by 7 a.m. the finishers were leaving the site," Loman said. "By 8 or 9 a.m. they had the control lines popped and the columns [contractors] were on the slab by noon and were pouring columns by 3 or 4 in the afternoon.

"They were stressing cables the next morning and dropping tables. So 24 hours after they poured on it, they were stressing cables and dropping them."

This was the scenario for all floors above the first two. These typical floors measured 13 ft. 4 in. floor-to-floor and were built with two pours per floor.

Other concrete contractors included AmeriSteel of Duluth, Ga., reinforcing steel; Precision Concrete of Alpharetta, Ga., placing and finishing; and DSI of Tucker, Ga., post-tension cables. The project topped out Sept. 25.

Outside, Inside

Curtain wall comprised of a combination of metal panels and granite makes up the exterior of the building. Subcontractor JAMCO, Marietta, Ga., handled the erection of the curtain wall system and installed the granite into it. This part of the project "went better than planned, better than scheduled," Loman said.

A two-story screen wall encircles a portion of the roof's perimeter, adding to the building's perceived height. The screen wall system is illuminated from within.

Interior work is relatively limited. Hardin and its subcontractors are finishing out six floors for SouthTrust Bank, and other contractors will complete interiors on eight others.

Here, though, the owner threw the construction team another, final curve - the desire to go for LEED certification.

"We got word they wanted to go LEED about halfway up the structure," Loman said. Still, the timing wasn't too bad, just prior to getting final documents for the interiors. Also, because it's a core-and-shell project, interior work wasn't too extensive.

"The core-and-shell materials is not a whole lot," he added. "It's mainly the main lobby." For this reason, the building will likely earn the indoor air quality credit.

"The lobby is primarily either marble or granite," Loman said. "You don't really have the high-VOC paints and caulks, as most of it is hard-surface materials. And we're using low-VOC paints and adhesives and caulks."

He said a major reason the project had a chance at attaining this certification in the first place was that it is part of a brownfield redevelopment, which is what Atlantic Station is considered.

Another factor in favor of achieving LEED was Atlantic Station's use of a central chiller plant for the entire development, meaning the SouthTrust building doesn't have a chiller, and all air-conditioning units are CFC-free.

The building is expected to earn points for the use of local materials and recycling because of the curtain wall is made up of recycled aluminum.

The commitment to LEED certification was important to the owner.

"It started with the site remediation and clean-up of the former industrial facility, continued with the installation of [the] sanitary and stormwater system, set a national precedent through a partnership for Smart Growth and air quality improvement with the U.S. Environmental Protection Agency and took the next logical step with the commitment to 'green' building construction," Leary said.

"Too much of what is built today is fully a function of a short-term proforma that gives no value to sustainable measures that not only positively affect the built environment on day one but pay back not only the building owner but the community as well over time," Leary added. "Instead of adding 3-5 percent to the capital cost of a building we are able to reduce that closer to 1 percent and then recover that cost through the more efficient operation of the building."

Hardin's Loman is pleased with the end results.

"I'm going to be real proud come April 1 when we turn it over," he said in February. "It's a really neat deal for this whole development and Atlanta. They've been talking about it, and it's becoming a reality."

Key Players:

Owner: Atlantic Station LLC, Atlanta
General Contractor: Hardin Construction Co., Atlanta.
Architect: Smallwood Reynolds Stewart Stewart & Associates, Atlanta