9/11 Memorial Museum Slurry Wall Counterfort Structure

The 9/11 Memorial Museum at Ground Zero features an exposed portion of the World Trade Center Towers’ original basement retaining “slurry walls”, named for their method of construction. The 60ft high slurry walls are subject to immense soil and groundwater pressure due to their close proximity to the Hudson River. Originally, these walls were supported by the basement floor slabs of the World Trade Center. When the floor slabs collapsed on 11 September 2001, the walls were tenuously supported by the debris at the site, and then steel cables temporarily supported the walls as debris was removed. Guy Nordenson and Associates, working with Davis Brody Bond and Simpson Gumpertz & Heger, devised a method to support the approximately 270ft wide portion of the slurry wall within the 9/11 Memorial Museum that exposes a full height segment of the original wall while providing adequate waterproofing and blast protection. The solution was to link the existing slurry wall with a new concrete liner wall, formed by a series of vertical beams in the soil along the existing wall’s back-facing joints. Additional reinforcements support both walls.