The SOMA Hotel project included a 9-story luxury Hotel on a lot approximately 100ft x 180ft in the Mission Bay District in San Francisco CA. Foundation's scope of work included the installation of over 400 H-Piles and a sheet pile shoring system.

The Project:

Foundation was listed to install over 400 H-Piles to construct a new luxury hotel in San Francisco, CA.  Due to existing soil conditions and to reach bedrock material, driven H-Pile at lengths from 215ft – 230ft was the selected choice for the deep foundation scope.  To reach these depths, the H-Pile was installed in 3 separate pieces.  Thus, a total of 1,209 pieces were driven and 806 splices were made, respectively.

Since each pile cap needed to be excavated, Foundation design-built a sheet pile shoring system that provided an adequate, safe working environment.

  • 20 indicator piles were driven and each was PDA tested
  • Over 16,000 man-hours were logged with no safety incidents

Challenges:

  • Because of the less-than-ideal footprint of the job site, the erection of the crane and unloading of material overlapped into the surrounding public areas.
  • Delivery coordination of material.  Since Foundation was not provided a laydown area, it was critical for our team to administer the logistics each pile delivery.
  • Pile installation.  In detail, the project footprint was within 1′ of an existing structure.  As a result, at times, the H-Piles were installed within inches of that structure.  When driving these piles, there was no room for error.

Innovative Construction Techniques:

  • Due to noise constraints, pile driving could only occur Monday – Friday, 8 am – 5 pm.  As a result, Foundation prioritized daily productions to ensure the schedule was met.
  • Planning ahead which provided cost savings.  Since the sheet piles needed to be removed, Foundation worked with the contractor to leave heavy equipment on the project site.  This saved the owner additional costs of mobilizing equipment to extract the sheet pile.
  • Due to the PDA testing Foundation conducted it was discovered, along with Geotechnical and Structural Engineers, blow counts could be reduced from 120 blows per foot to 75 blows per foot.  This helped reduce the number of days on the project schedule.