Slurry Wall Design Techniques and Construction Practices Over the Last 50 Years in Northeastern United States

Slurry walls, also known as diaphragm walls, were first introduced to the United States in the early 1960s for deep excavation projects. The technology was patented in the late 1940s by ICOS in Italy. The first major application of slurry wall technology occurred in the mid-1950s for the Paris Metro Line 8, where the technique was used to create a 100-foot (30-meter) deep excavation. The slurry wall was laterally supported by bracing and tieback anchors. After a decade of successful development and demonstration, slurry walls were introduced to the U.S. in the early 1960s. The first major U.S. application of slurry walls took place in the late 1960s for a 70-foot deep excavation in Lower Manhattan, New York City, during the construction of the foundations and below-grade structures for the original World Trade Center Towers. The slurry wall was supported by multiple levels of high-capacity strand tieback anchors installed in rock. The construction proved successful, providing lateral support for the deep excavation and effective groundwater control, enabling foundation construction in the dry. Following the success of the World Trade Center project, slurry wall technology was widely adopted in major U.S. cities. It became essential for constructing tall buildings requiring significant below-ground space for parking and other facilities, deep subway stations, and shafts for launching and retrieving tunnel boring machines. The technology allowed for safe excavations, worker protection, and the safeguarding of adjacent structures, reducing construction risks for contractors, owners, and the public. This paper explores the advancements in slurry wall analysis, design, and construction methods over the past 50 years, with a focus on case histories from northeastern U.S. cities, particularly Boston, New York City, Baltimore, and Washington, D.C.