Planning ahead for Columbia expansion.

The long-awaited conceptual plans for the 6.8 million s/f expansion of Columbia University were unveiled this week revealing a design that will create a subterranean bathtub equal to the World Trade Center bathtub.

The scale of the multi-billion dollar project has prompted the team set up to plan the initial phases of construction to fast track the appointment of a construction management firm.

Though actual construction of the project is not due to beging until early 2008, the management firm is expected to be announced in January 2007 due partially to shifting pressures on developers to secure materials early during the worldwide construction boom.

"The amount of work that is going on has caused the dynamics to shift slightly. The construction manager will help us determine if we need to order materials, like the skin for the building or a foundation contractor earlier than we would have previously done. Issues of material availability have become much more acute in this sort of construction environment," said Marcelo Velez, assistant vice president for Manhattanville Capital Projects, a team headed by the Renzo Piano Building Workshop and Skidmore Owings and Merrill and including 40 professionals such as wind experts and geothermal technicians who planned the first phase of the underground expansion.

Other materials Velez suspects may have to be ordered well in advance of construction include curtain walls, which are only manufactured by three or four firms nationally, and whose production has been rumored to be locked up by Las Vegas developers for six months to a year.

The size of the tract roughly bordered by 125th street, 133rd street, Broadway and 12th Avenue in Manhattanville ranks among other boom-time mega-projects which officials hope could help revitalize the area by bringing over 7,000 jobs, connecting West Harlem to the West Harlem piers and bringing cultural resources to the community, according to La-Verna Fountain, assistant vice president of public affairs for Columbia University.

Velez said "This is really one of the most exciting projects to take place in New York City in the past 20 years and I feel fortunate to be a part of it."

Excavation workers will tunnel 100 feet below grade to a layer of relatively impermeable soil to build slurry walls that will protect the bathtub containing seven floors of underground space. The slurry walls were necessary because that site had an unusually low level of rock for Manhattan, which allowed the high water table to seep through. The grip of the slurry walls against the dense layer of soils should seal the water out until the floor of the bathtub is created, Velez said.

The slurry walls will be installed in sections of connecting panel which are 20 feet long each and will ring around the designated blocks. Later, the pile foundation will be poured, followed by the installation of the building ground floor slab. Finally the buildings will be created above grade.

"We are planning on tackling this project one city block at a time," Velez said.

Eight to ten feet of the dug-out sub-surface will ultimately belong to the city, and the dirt taken out will be reused by the utility companies for setting lines. The area beneath that space will belong to the University.

It was important for the University to create centralized underground spaces to keep the streets on the grid above clear for traffic and will include a central energy center for steam and chilled water to be filtered, a science support space, a loading dock, and a place to offload trucks below ground, Velez said.

Though the expansion has met some resistance in the West Harlem Community by residents afraid of gentrification and public approval processes have yet to be met, the university has been able to procure 65% of the private properties they will need to see the project through to completion, Fountain said.