Harry Tracy Water Treatment Plant Long-term Improvements Project, San Bruno, California

Construction activities in progress for the new treated water reservoir. Image courtesy Water System Improvement Program (WSIP) Peninsula.

The HTWTP treats water from the Crystal Springs Reservoir System to be supplied throughout the Northern Peninsula. Image courtesy Water System Improvement Program (WSIP) Peninsula.

The 11 million gallon treated water reservoir enables the plant to supply up to 140 million gallons of emergency water a day when completed in December 2014. Image courtesy Water System Improvement Program (WSIP) Peninsula.

The Harry Tracy Water Treatment Plant (HTWTP) is located approximately 1,000ft east of the San Andreas Fault in San Mateo County, San Bruno, California, US.

Owned by San Francisco Public Utilities Commission (SFPUC), the plant treats and delivers water stored in Crystal Springs and San Andreas reservoirs to the people throughout the Northern Peninsula. It is also the only source providing emergency water to the San Francisco Peninsula.

In March 2011, construction was launched on a $283m improvement project involving seismic retrofits and electrical upgrades to enhance the plant’s treatment capacity. Construction was completed in April 2015.

Details of the HTWTP improvement works

The improvement project primarily involved replacement of the existing 6.5 million gallon and eight million gallon treated water reservoirs with a new 11 million gallon treated water reservoir. It also included the construction of five new filters, replacing the existing 0.5 million gallon washwater tank, conversion of washwater clarifiers to equalisation basins, installation of new high-rate clarifiers, and completion of hydraulic improvements to various treatment units.

Other works included the installation of a new ozone generation facility, sedimentation basins, sludge thickening and dewatering facilities, an effluent pipeline and a raw water pumping system, as well as electrical and instrumentation upgrades.

The largest and most complex part of the project is the new 11 million gallon treated water reservoir, which is capable of supplying up to 140 million gallons of emergency water per day. The reservoir, supported by 88 columns, is built to withstand earthquakes along the San Andreas Fault.

There are six major shutdowns during the ongoing upgrade works. The electrical works include relocation of all electrical equipment in the west chemical building, which was demolished, moving plant operations into phase 3 of the operations building, and installation of three new ozone generators. A 480V emergency power system was installed in the ozone building area.

Other works included the replacement of the ozone destruct units and ozone destruct blowers. The new 4,160V standby power generator will also be commissioned for operations.

Contractors and suppliers for the project

SFPUC awarded Kiewit Infrastructure West (KIW) a $174m construction contract for the HTWTP improvement project in 2011. The draft environmental impact report (EIR) for the proposed improvement works was prepared by ICF International. The alternatives analysis report was prepared by Parsons as part of the planning phase.

Geotechnical engineering analysis and geotechnical and geological exploration for the design of the HTWTP long-term improvement project was conducted by Geotechnical Consultants.

Mass Electric Construction (MEC) provided its technical expertise to perform the electrical works at the HTWTP improvement project.

R&W Concrete Contractors conducted some of the concrete works at the WTP. Construction Testing Services and Construction Management & Engineering Professionals (CMPROS) were also involved in the project.

Design and construction management services were provided by JTD Engineers. Avila and Associates were contracted to help the improvement project meet the necessary regulatory requirements.

STRUCTUS is the structural sub-consultant for the improvement project. It provided filtration improvements, seismic retrofit design for the two existing flocculation basins and long-term improvements to other civil structures, including the existing operations building, gallery building, ozone building and office and storage building.

PMA Consultants was appointed to monitor the project performance in coordination with the contractors.

History of the San Bruno plant

The 80 million gallon a day capacity HTWTP, formerly named San Andreas Water Treatment Plant, was built in 1972 at an estimated cost of $7.6m. The facility is spread across 52.3 acres of land in an unincorporated area of San Mateo County near the City of San Bruno and the City of Millbrae.

It was upgraded in 1992 with an estimated investment of $55m, increasing its capacity to 1,160 million gallons a day. The upgrade works involved the installation of ozone pre-treatment and construction of new filtration units to meet the water needs of the region until 2030.

In 1994, the plant was renamed the Harry Tracy Water Treatment Plant.

Benefits of the HTWTP improvements project

The upgrade project is part of the larger $4.6bn Water System Improvement Programme (WSIP), which involves rehabilitation and expansion of the 100-year-old Hetch Hetchy Regional Water System. The WSIP involves more than 80 projects, covering seven countries from the Central Valley to downtown San Francisco.

The upgrades at HTWTP improve the quality of drinking water for San Francisco and San Mateo County.