Event Date
The Biosolids Digester Facilities Project (BDFP) is part of a multi-billion program to update and replace the aging Southeast Water Pollution Control Plant (SEP) in San Francisco, California. The program involves the construction of new solids treatment, odor control, energy recovery, and associated facilities for the San Francisco Public Utilities Commission (SFPUC). The BDFP will produce higher quality “Class A” biosolids, meet projected wastewater treatment needs through 2045, reduce odors, and improve the ability for critical facilities to withstand a 7.8 magnitude earthquake. Geotechnical challenges include non-engineered fill, soft, compressible clay, strong seismic shaking, liquefiable soil deposits, and a confined aquifer. A comprehensive seismic and geotechnical investigation was carried out to provide foundation solutions for the various biosolids digester facilities. The analyses included developing design acceleration response spectra and analytical modeling of the foundation systems to optimize foundation design for multiple facilities under challenging subsurface conditions. Below grade structures required extensive drainage and dewatering design to address the impacts of the confined aquifer. For the main digester complex, a slurry diaphragm shoring wall extending over 150 feet in length was constructed to cutoff seepage, and over 500 micropiles were installed to resist hydrostatic uplift forces. A full-scale lateral and vertical load-test program for large diameter drilled shaft foundations was also performed to optimize the foundation design. The foundation design will significantly enhance the system resiliency of the new biosolids digester facilities against geotechnical and seismic hazards.
Speaker Bio
Dr. “Neel” Neelakantan has over 35 years of research and consulting experience in geotechnical engineering, with over 32 years of management, design, and construction experience in the San Francisco Bay Area. He has served as the principal in charge or the lead geotechnical engineer for several large infrastructure projects including SFPUC’s Biosolids Digester Facilities Project (BDFP); SFPUC’s Bay division Pipeline No. 5, Harry Tracy Water Treatment Plant Improvements, the new Bay Tunnel, the BART Earthquake Safety Program, etc. His Bay Area project experience also includes the BART Extensions Program in the early 1990’s; bridges and other highway structures; airport facilities including runways, taxiways, and aprons; dams and reservoirs; water and wastewater treatment facilities; flood control projects; and tunnels and pipelines.