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Chabot Dam Seismic Upgrade - EBMUD


Key Features 


  • 135-foot high and 500-foot long sluiced fill and wagon fill earth dam constructed in 1892

  • 17 continuous Cement Deep Soil Mixed (CDSM) shear walls, embedded into bedrock, installed at downstream toe of dam

  • 500-foot long, 30-foot deep, and 7-foot wide seepage trench excavations


Geotechnical Challenges


  • Complex bedrock conditions abruptly varying between shallower volcanic rock and deeply weathered and sheared metamorphic rock

  • Soil includes 30 to 70 feet of liquefiable fill and areas of undocumented fill and construction debris

  • Complex testing and inspection of fill materials in seepage trench with very limited access


Innovative Solutions


  • Continuous CDSM panel walls used to strengthen dam and mitigate seismically induced deformations

  • Developed QC methods and criteria with project CM, Design Engineer, and DSOD to ensure achievement of design needs in complex and challenging geologic conditions

  • Seepage trench used to reduce hydraulic gradient and increase dam stability

As an integral part of the Construction Management (CM) Team, A3GEO worked closely with the project CM (Kleinfelder), design engineer (Terra Engineers), owner (EBMUD) and the contractors while performing geotechnical inspections during CDSM installation and testing, seepage trench construction and dam embankment fill placement.  CDSM construction was completed in November 2016.  Seepage trench and dam embankment construction is currently underway.

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