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

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The San Francisco Public Utilities Commission’s $2 billion Biosolids Digester Facilities Project is replacing aging solids-treatment infrastructure at the Southeast Treatment Plant, which handles over 80% of the city’s wastewater. The upgrade aims to improve odor control, earthquake and sea-level-rise resilience, and long-term operational reliability.<br /><br />Using a construction-manager/general-contractor delivery model, the project engaged Malcolm Drilling as its Foundation Core Trade Partner during design. Early collaboration with the owner, construction manager, and design team allowed the contractor to contribute construction expertise, evaluate options, and conduct early field testing. For example, load tests supported the selection of Continuous Flight Auger piles in place of some drilled shafts, saving cost and time.<br /><br />The site’s difficult ground conditions—including soft, compressible Young Bay Mud, connected aquifers, existing foundations, and active rail lines—made excavation support especially challenging. Testing showed that a proposed 70-foot Cutter Soil Mix wall would not adequately control groundwater. The team instead selected a deep, reinforced-concrete diaphragm wall for the approximately 41.5-foot-deep Facility 610 excavation. Extending about 158.5 feet below grade, the wall provided structural support and groundwater cutoff while meeting strict movement limits. Monitoring during excavation recorded wall movements of approximately 0.5 inches or less, with groundwater drawdown limited outside the excavation.<br /><br />Construction required extensive coordination among concurrent foundation, shoring, dewatering, and excavation activities. At peak, the site handled about 80 concrete-delivery trucks and 80 spoil trucks per day through limited access points. The project also met local business participation goals by engaging San Francisco subcontractors.<br /><br />The paper concludes that early specialty-contractor involvement improved constructability, design decisions, coordination, and project efficiency. The collaborative approach helped the team address complex technical and logistical constraints and achieve meaningful cost and schedule savings.

Keywords

San Francisco Public Utilities Commission

Biosolids Digester Facilities Project

wastewater treatment

foundation core trade partner

construction-manager general-contractor

continuous flight auger piles

diaphragm wall

groundwater control

young bay mud

constructability collaboration