The Central Artery/Tunnel (CA/T) Project relocated Boston’s elevated Central Artery below ground. The CA/T tunnel walls used soldier pile tremie concrete (SPTC) slurry walls as a component of the final structure. During later stages of construction, engineers discovered inclusions, clay pockets, and incompletely-filled areas in the SPTC walls. In response, CA/T performed a survey of the walls and then required tunnel constructors to perform their own evaluations of wall irregularities, and to design and implement repairs. SGH provided investigative services and designed wall repairs for multiple construction contracts of the CA/T project.