Gates Foundation Headquarters, Geotechnical Services

GeoEngineers’ geotechnical solutions help site, design and build this marquee green development project in Seattle

Practices

Location

Seattle, Washington

The Bill & Melinda Gates Foundation is a private family foundation that funds education, health and development programs around the world. The Gates family envisioned building a new world headquarters for the foundation on urban land in Seattle, Washington. GeoEngineers was fortunate to be involved from the very beginning—long before a site was selected—and remained on the project through the environmental cleanup, building design and construction phases.

GeoEngineers’ geotechnical engineers collaborated with the integrated project team from the conceptual phases to final design for the foundation’s campus development. The final design for the 12-acre site consisted of a parking garage and three six-story office buildings that offer a combined 1.3 million square feet of office space.

The project presented an array of complicated geotechnical problems for GeoEngineers’ geotechnical experts to solve, including:

  • Highly variable groundwater conditions and the presence of compressible fill and clay soils across the site.
  • Two immense water tanks—one to hold rainwater and the other to optimize cooling—were called for in the sustainable design, each requiring detailed geotechnical analyses to meet stringent performance requirements.
  • A 6-foot-diameter, 100-year-old brick sewer lay beneath the planned basement level and was not to be disturbed by the excavation or building loads.
  • Geotechnical designs had to accommodate GeoEngineers’ significant environmental remediation plans for the site.

GeoEngineers’ environmental studies, analyses, and extensive experience with brownfields projects were also a critical part of the site-selection and design process. For a full discussion of the GeoEngineers’ environmental work on the project, see the related project profile.

Approach

  • Collaborated with the project team throughout design to identify the most cost-effective foundation and shoring solutions
  • Provided sophisticated geotechnical analyses for unique design issues to provide the team with a detailed understanding of the anticipated loads and structural response
  • Developed design recommendations for temporary shoring systems that consisted of both soil nail walls and soldier pile and tieback walls
  • Created sophisticated shoring and foundation designs to accommodate the two water tanks
  • Assessed impact on the sewer and nearby area with extensive modeling of the excavation sequence
  • Provided full-time special inspection of shoring systems and part-time observation of foundations and site earthwork to confirm compliance with plans and specifications and to provide practical solutions to unique construction conditions

 

Results

  • Created highly efficient foundation and shoring systems
  • Kept project on budget and schedule with daily operational plan and integration with contractor
  • Facilitated effective communication and collaboration with the project team during both design and construction
  • Made recommendations that helped the general contractor protect existing infrastructure from adverse impacts during construction
  • The foundation campus was awarded LEED©-NC (Leadership in Energy and Environmental Design for New Construction) Platinum certification from the United Stated Green Building Council, and is the largest, non-profit LEED©-NC Platinum building in the world.
  • The project also provided GeoEngineers with the opportunity to advance the understanding of soldier pile and tieback shoring systems through a full-scale demonstration project that identified opportunities for significant cost savings on future projects along with improved performance of below-grade basement walls. See the related news story for more information about the soldier pile and tieback demonstration project.

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