by : Nicholson Company
- Location: New York, NY
- Owner: Port Authority of New York & New Jersey
- Technique(s) Utilized: Anchors, Diaphragm Walls, Jet Grouting, Secant Pile Walls, Micropiles
- Subsurface Conditions: Fill over sands and silts with till and/or decomposed rock over hard Manhattan schist bedrock
- Approximate Key Quantities: Diaphragm Wall - 40,000 square feet, Jet Grout Columns - 122
Secant Pile Wall - 10,000 square feet, Slurry Wall - 6,000 square feet, Tieback Anchors - 285
A decade after the devastating attacks on the heart of New York, the city continues the remarkable process of rebuilding the former site of the World Trade Center (WTC). Nicholson has been at the site and an integral part of the process from the beginning – from securing the area for search and rescue to being a part of the extraordinary and ongoing reconstruction work, which began in 2006.
PROJECT BACKGROUND
With the opening of the World Trade Center Memorial, slated for September 11, 2011, downtown New York City will become more congested than ever. On a normal day in the city, 200 commuter buses make daily stops in the Financial District, in addition to the dozens of tour buses canvassing the streets at any given time. With the opening of the WTC Memorial, it is estimated that an additional 200 tour buses will be making their way into the city on a daily basis. The additional buses compound an ongoing problem for New York City in that parking is at a premium, but they also echo the security concerns that have become a reality for the city's visitors and tenants since the attacks. In response to these issues, the Port Authority of New York and New Jersey commissioned the construction of the World Trade Center Vehicle Security Center and Tour Bus Parking Facility (VSC.) The VSC will function as part of the comprehensive, state-of-the-art plan for the screening of buses, trucks and cars entering the WTC and its parking facilities through the basement level. This below-grade structure requires a five-story deep basement with connecting ramps into the West Bath tub Area, which includes the 9/11 Memorial Site and Museum, the new Freedom Tower and the PATH subway line.
THE WORK
Nicholson has served an integral role in the construction of the World Trade Center Vehicle Security Center and Tour Bus Parking Facility (VSC).
The initial scope of Nicholson's work at the VSC, which was carried out in JV with EE Cruz, was to create a water-tight excavation, measuring 220 ft. by 450 ft. and reaching a depth of 60 ft. The first phase of the project included the installation of a 40,000 square foot diaphragm wall with 210 tieback anchors, as well as 160,000 cubic yards of bulk excavation, 10 jet grout columns, 320 rock bolts, 6,000 square foot temporary slurry wall, cast-in-place concrete, compensation grouting and pipe struts.
The diaphragm walls installed by Nicholson will form the southern part of the VSC, which will include a parking area to accommodate the increased number of tour buses entering the WTC.
In March of 2011, Nicholson began working for Yonkers Construction on the earth support and water cutoff phase of development, which includes 10,000 square feet of secant pile wall, 75 tieback anchors, 15 micropiles (200 tons) and 122 jet grout columns with lengths ranging from 15-40 feet.
THE RESULT
Working in the heart of one of the most heavily populated cities in the world creates a unique and ongoing set of challenges. Nicholson's exposure to those challenges, beginning with the initial excavation of the site following the attacks, and continuing on through the latest phase of the VSC's development, has been a critical success factor.
The VSC, which is slated to open in 2012, will contain approximately 50 tour-bus parking spaces in total, which should effectively accommodate the additional tourist traffic entering the newly rebuilt WTC.
