Cutter soil mixing, tie back, internal bracing, and jet grouting columns multi-residential project on Block 9 in San Francisco consists of a 43-story tower and two smaller towers on either side. While it is being constructed as one building, it will have the appearance of a high-rise building bracketed by two low-rise buildings. In total, there will be 570 residential units, shared open spaces, amenities, and retail along Folsom Street. A shared underground car and bicycle parking garage will accommodate parking for all units.
For Malcolm, this project presented an opportunity to execute a well-planned and well-executed approach to support of excavation (SOE) on an extremely challenging site. At 6-stories deep, this project was the deepest planned excavation in the Transbay District at the time, and addressed difficult soil, bedrock and groundwater conditions, known deep obstructions, and provided tight deformation control for sensitive adjacent residential and freeway structures. The excavation was supported by a combination of cutter soil mix (CSM) walls, tie-backs, internal bracing, and jet grouting columns at the base to mitigate liquefaction concerns.