Historical NotesLeo M. Halley was a civil engineer who worked for the PANYNJ’s World Trade Engineering Design Division, which oversaw construction of the World Trade Center in the 1960s. Of note, Halley was closely involved with the creation of the site’s slurry wall, built as a concrete foundation beneath the buildings for the purpose of keeping water from the nearby Hudson River out of the worksite. In 1966 or 1967, in recognition of his contributions to that project, Halley was awarded a
plaque whose materiality and design reference the tiebacks which serve as a distinctive visual and functional feature of the Slurry Wall itself.