The Benefits of an Early Contractor Involvement For A Mega Project In San Francisco-PPT Presentation

PPT Presentation

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The $2 billion Biosolids Digester Facilities Project is upgrading San Francisco’s Southeast Treatment Plant, which handles wastewater for more than 80% of the city. The work is intended to reduce neighborhood odors, improve operational efficiency and redundancy, and prepare facilities for earthquakes and sea-level rise.<br /><br />Malcolm Drilling was selected in 2018 as the foundation core trade partner under the project’s CMGC delivery method, with Brierley Associates as shoring designer. Early involvement—beginning 18 months before construction—enabled weekly coordination, development of logistics and schedules, and early pursuit of long-lead permits. It also supported value engineering, including substituting continuous flight auger piles for some drilled shafts and conducting onsite pile-load and dewatering tests.<br /><br />At Facility 610, the team constructed a 3-foot-thick reinforced diaphragm wall extending about 160 feet below grade around a large, 42-foot-deep excavation. The wall penetrated low-permeability Old Bay Clay to provide groundwater cutoff. Design and construction had to address active rail lines, high groundwater, tieback anchors that could conflict with future foundations, and connections to adjacent facilities. Coordination, design iterations, specialized drilling and grouting methods, and BIM clash detection helped manage these constraints.<br /><br />The construction sequence included diaphragm-wall excavation and concreting, dewatering, staged excavation and tieback installation, and construction of the mat slab. Monitoring showed satisfactory performance, with lateral wall deflections at Facility 610 limited to approximately 0.5 inches or less. Overall, the presentation demonstrates how early contractor participation can improve constructability, planning, risk management, and value on a complex infrastructure project.

Keywords

Biosolids Digester Facilities Project

San Francisco

Southeast Treatment Plant

wastewater infrastructure

diaphragm wall

foundation engineering

Malcolm Drilling

groundwater cutoff

earthquake preparedness

sea-level rise resilience