2nd and PCH

Long Beach, CA

The Geopier Impact® system was chosen to provide superior mat and footing settlement control, while also reducing the potential for liquefaction

  • Owner: CenterCal Properties, LLC
  • General Contractor: WE Oneil Const
  • Geotechnical Engineer: Twining, Inc.
  • Structural Engineer: Ficcadenti Waggoner and Castle
Client's Challenge

The project consists of constructing a 220,000 square foot multi-level mixed-use development with column loads of up to 980 kips and all loads up to 18 kips. The new structure will provide retail, dining and parking while overlooking the Long Beach Marina and Alamitos Bay area.

Subsurface Conditions

Subsurface conditions consist of moderately to highly compressible clay and liquefiable sand layers in the upper 20 feet, underlain by stiff clay and silt and loose to medium dense sand and silty sand. Groundwater was encountered at 10 feet. Western Ground Improvement (WGI) and Geopier Foundation Company (GFC) were requested to provide a ground improvement solution to reduce compressibility of the clay and silt and liquefaction settlement of the sandy soils.

Geopier® Solution

The Geopier solution consisted of using over 3,000 Rammed Aggregate Pier® (RAP) Impact® elements. The displacement RAP elements were installed to depths of about 28 feet below finished grades to reduce the compressibility of the soft clay and silt under a 5,000 psf bearing pressure and to mitigate liquefaction related settlement in sandy soil to levels acceptable to the design team. During construction a pressurized oil line and an old clay storm sewer pipe were identified to be within 2 to 10 feet of RAP supported footings. Due to concern for damaging the utility lines during RAP installation and applying foundation stress to the utility lines during and after building construction, WGI and GFC worked with the design team and general contractor to revise the installation methods near these lines. A combination of pre-drilling and grouted aggregate were used to minimize possible damage to the utilities and to transfer footing stress to below them. All piers were installed without damage to the utilities.