Hitting rock bottom to finish on top

 EE Cruz reaches substantial completion of top-down construction for Columbia University’s campus expansion

After three and a half years of hard work and dedication, EE Cruz and joint venture partner Nicholson Construction have reached substantial completion for the slurry wall and foundations portion of Columbia University’s West Harlem campus expansion.

Completed base contract work includes over 150,000 square feet of watertight slurry wall and 96 load-bearing elements to support the Jerome L. Green Science Center. Using top-down construction, EE Cruz tunneled under the first-floor slab to construct two sub-basement floors, while another construction team, under a separate contract, simultaneously constructed the building’s six-story superstructure. Constructing the structural slabs as excavation progressed eliminated the need for extensive temporary slurry wall bracing and tiebacks.

The team encountered numerous obstructions during the drilling and excavation phases of the project, but successfully removed over 100,000 cubic yards of soil through an opening left in the first-floor and basement slabs. Careful planning and coordination were required to deliver and place materials for structural concrete slab construction without disrupting the ongoing excavation through the single opening.

Once construction was complete for the lower foundation slab, the project team turned to construction of the building’s under slab drainage system. The drainage system, composed of perforated high density polyethylene tubing and washed stone, was installed on top of the foundation slab and tied into various drainage pits created during slab construction. 9,000 tons of drainage stone were imported and placed to build the 2.5-foot thick layer.

In March 2012 a contract change order added 206,000 square feet of slurry wall to the scope of work and increased the contract value by $46 million. This additional phase two slurry wall encircles the 17-acre campus. Future construction at the site will include additional buildings for academic research, parking, student housing facilities support and commercial space.

As of the writing of this article, the project team is working hard for a strong, successful close by the end of June.