Deep Soil Mixing and Ground Improvement on the Transbay Terminal

Transbay Terminal is a transportation complex in the South of the Market area of San Francisco, roughly centered on Mission Street and Howard Street, Beale Street, and 2nd Street west and east. Malcolm Drilling was one of the Joint Venture partners of DND Construction, which performed the Cement Deep Soil Mixing (CDSM) shoring and ground improvement scopes for Balfour Beatty Infrastructure, Inc. on the Transbay Transit Center project in San Francisco, California.  The project consisted of 45,700 cubic yards/379,000 square feet of overlapping soil mixed columns measuring 3 feet in diameter with 2 feet in the center. Depths were predominantly 105 feet, although the buttress ground improvement and a portion of the shoring wall extended up to 120 feet deep.  Flange beams with lengths of 95 feet and 120 feet in length were installed in every other column. The project also included remobilizations to facilitate the shoring wall’s crossing of multiple active city streets.