Event Date
The 50 at First development in San Francisco, California consists of the construction of 910-foot-tall tower over a 3- to 4-level basement. The subsurface consists of undocumented fill and compressible marine deposits over dense sand and stiff, but compressible clay. The excavation required to construct the basement removes some of the problematic soils; however, it brings the loads closer to the top of the compressible clay. Due to its weight and potential for settlement, the tower is supported on large-diameter drilled shafts that extend into bedrock (over 330 feet below street grades).
After completion of the foundations and basement in 2020, the project stalled; however, a revised 910-foot-tall tower is currently being redesigned, with construction expected to resume in 2027. This presentation will discuss some of the design and construction challenges related to the foundations and shoring for the development.
Speaker Justin Ray has worked at Langan for the last 14 years after graduating from UC Berkeley with his Master’s degree in Geotechnical Engineering. With Langan, he has provided geotechnical engineering services for numerous projects throughout the Bay Area and Sacramento, including commercial and residential developments for mid- and highrise buildings, and education and medical facilities. After spending 8 years in the Bay Area, Justin has been the geotechnical lead of Langan’s Sacramento office for the past 6 years.