An historic proposition
Mid-1800 warehouses preserved at New Orleans Marriott site

By Sam Barnes

An appreciation of history has been essential during construction of a concrete parking basement at the new Marriott Convention Center Hotel in New Orleans.

An owner stipulation that two 150-year-old warehouses be incorporated into the $35 million hotel required some inventive preliminary work so excavators and pile drivers could work within the confines of the warehouse walls.

Three similarly sized cotton warehouses originally occupied the site, but only two of the warehouses have historic significance. The third was demolished to make way for the hotel's 14-story tower.

"We had to brace the walls all the way around before doing anything on the inside of the buildings," said Ken Flower, project manager with design-build contractor Carl E. Woodward LLC of New Orleans. Structural engineer Jeffrey Thomas Avegno Inc. of New Orleans designed the bracing system.

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Boh Bros. Construction LLC of New Orleans drove perimeter sheet piles 6 ft. inside the basement walls to prepare for the excavation. The 35-ft.-long sheet piles were left in place to serve as forms for the basement floors and walls.

"After pouring the concrete for the basement floors, it was physically impossible to pull the sheet piles out," Flower added.

All of the excavation had to be performed without the benefit of a de-watering system, which would have negatively impacted adjoining properties. To compensate, the Carl Woodward crew performed numerous "mini" excavations.

"We'd excavate a small portion of it and immediately put in a concrete dry bottom, while pumping out any type of surface water," senior project manager Legier Kuhner said. "We'd pour it against the sheet piles and lock those in."

The basement slab reaches 5 ft. thick in pile cap locations and the walls are 1 ft. thick. Once complete, the one-level basement garage will reach about 50,000 sq. ft. and include 108 parking spaces.

Boh Bros. Construction drove timber and precast concrete piles as foundation for the basement and hotel using a "follower" to drive the piles to the desired depth.

"Because of our proximity to the Mississippi River we knew the pile driving was going to be challenge," Kuhner added. "In many locations the piles would hit 'refusal' before getting to their final location. We'd just excavate around it and cut the pile off."

"When it's all said and done, the warehouse walls will look much like they did from the outside," Kuhner said.

Flower said there is currently a major push to get the hotel dried in to the seventh floor by July so that mechanical and electrical crews can begin work on the lower floors.

CECO Concrete Construction LLC of Slidell began construction of the hotel tower with a significant shoring operation this spring. The shoring is being performed in two phases, one to build the hotel tower and one to build an adjoining two-story section. Separate crews are performing each phase.

Nearly all of the concrete pours begin at 2 a.m. and finish by 7:30 a.m.

"The hotel is made entirely of concrete, 95 percent of which is post-tensioned with some minor reinforcing steel in the two-story section," Flower said. The hotel's fourth through 14th floors have 7.5-in.-thick slabs and the bottom floors measure 8 in.

The lower floors will support a ballroom, lobby and restaurant.

The exterior of the building will be made of brick and glass fiber-reinforced concrete panels supplied by GFRC Cladding Systems of Garland, Texas. Precast erection was expected to begin in late spring.

About 90 percent of the panels have already been manufactured, Flower said. The architectural precast is being produced in a variety of dimensions.

The deliveries will be made to the site "just in time" and the panels will be lifted and placed directly from the truck.

"We'll keep moving forward with the precast erection; it should never really stop," Flower added. "We hope to have the entire structure dried in by mid-October."

Mechanical work will require the installation of three large chillers on top of the hotel tower and interior work will include some aesthetic installations within the hotel lobby. The hotel will have three elevators that service all floors and one elevator that will service the first two floors.

"The lobby is going to have the nicest finishes, including a lot of millwork cladding on walls and columns," Flower said.

A ballroom on the first floor will have a two-story-high ceiling and a steel joist and metal roof. Concrete beams measuring up to 18 by 30 in. will run throughout the ballroom.

Carl Woodward performed design of the hotel as part of a joint venture with Trapolin Architects of New Orleans.

"Trapolin has a lot of experience with building projects in the downtown area and we felt their experience would greatly expedite the project," Flower said. Although design began in 2001, permit delays pushed groundbreaking to early 2003.

Once finished in May, the 331-room hotel will measure about 326,000 sq. ft. and have a 47,000-sq.-ft. basement.

Useful Resource

For up-to-date information about the hotel's progress, go to: http://marriott.com/news/