Concrete for CATS

Project marked the largest yet for Seretta's mid-Atlantic division

By Bea Quirk

Seretta Construction Mid-Atlantic LLP doesn't do much government work, but when one of its major general-contractor clients, Charlotte-based Edifice, asked the concrete company to bid on a bus maintenance facility for the city of Charlotte, it gave it a shot.

The $3.7 million contract is the largest Seretta has been awarded since opening its Charlotte division in May 2002.

"Seretta stood up to the plate on this one," said Kyle Hanrahan, senior project manager for Edifice. "This project requires expertise in concrete, and they do it with excellent quality."

The $38 million project encompasses five buildings on 25 acres for the city-owned Charlotte Area Transit System: a two-story, 36,000-sq.-ft. office building; 72,500-sq.-ft. maintenance building; 27,000-sq.-ft. fuel and wash facility; 33,000-sq.-ft. paint and body facility; and 400-car parking garage. There are also nine bus shelters.

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The existing facility was built for 200 buses yet is now taking care of a 300-bus fleet. This new facility is being designed in anticipation of a 400-bus fleet by 2010.

About 600,000 sq. ft. of concrete is used throughout the site. The three precast buildings for bus maintenance feature floors with 8-in.-thick concrete slab - instead of the standard 4-in. - with two mats of reinforcing steel. The bus shelters are made of concrete with metal canopies. Concrete 10 in. thick will also be used for the paving, which covers 300,000 sq. ft.

"We went with concrete paving because, with the weight of the buses (up to 40,000 lbs. each with passengers) over time, asphalt just wouldn't work," said Brad Miller, manager of operations for CATS. He is acting as the owner's co-project manager with Michelle Haus, who is representing the city's Engineering and Property Management Division.

"This is not a run-of-the-mill project," said J. Scott Hosking, Seretta division vice president based in Charlotte. He said the job requires a lot of handwork by skilled craftsmen. For example, a mineral shake-on hardener - in the form of a fine powder - is being applied by hand to all the surfaces to add durability.

In addition, the floors of the bus facilities will be heated. This means that after one layer of rebar is in place, a plumbing contractor installs German-made flexible tubing above it. Concrete workers then add the second layer of rebar but must work with extreme care not to puncture or rip the tubing. Extensive handwork is also required because the floors have a number of recesses.

Because of the handwork and the cramped nature of the site a laser screed can't be used to pour the concrete. A line system pump is being used instead, but that means pours are limited to 5,000 to 7,000 sq. ft. at a time.

"It's a slower project than we're used to," Hosking said. But even with some delays caused by rain, the project is slated to be finished on time by February. Work began in October 2003 and is inspected by city inspectors and an independent company hired by the city.

All five buildings are going up concurrently with up to 250 workers onsite and 100 subcontractors and vendors. A supervisor has been assigned to each structure. "We use a short-track scheduling program and have lots of meetings to coordinate all the activity," Hanrahan said.

Shortages and price increases in concrete and rebar have not negatively impacted the project, but there have been some changes. Hosking said Saturday pours were eliminated, and he and other contractors have ordered materials well ahead of time in case of delays. He did that with dowel baskets, which then arrived well before they were needed. With space onsite at a minimum, he had to store them at the supplier until they were needed.

"Everyone has been dealing with shortages - even down to the chain-link fence supplier," Hanrahan said. "We've come close and been nervous, but we haven't been impacted by shortages yet."

Thanks to Seretta's contract with its longtime concrete supplier, prices were locked in well before the increases. "The cost of the project isn't being impacted," Hosking said.

The local project architect - which has a representative onsite every day - is Morris Berg Architects. "We went through an extensive planning stage when we talked to the people who actually maintain the buses and who operate them. so we know what functions will be performed in each building," Miller said. "The result was a detailed design criteria book that was used as a guide for the architect."

The site sits on a major thoroughfare connecting the center city with a newly developing area, the South End. Residences and commercial uses are mixed throughout the area, which necessitated some design considerations. The maintenance buildings are located in the inner part of the site so they are not visible from the street, and the precast concrete structures feature a brick façade.

Adjacent to the site will be a maintenance facility for CATS' light-rail system, which is just beginning construction. Haus said the maintenance facility project is currently out for bid.

Project Team:

Owner: Charlotte Area Transit System
General Contractor: Edifice Inc., Charlotte
Concrete Contractor: Seretta Construction Mid-Atlantic LLP, Charlotte, a division of Seretta Construction, Altamonte Springs, Fla.
Architect: Morris Berg Architects, Charlotte