The Oceanside Water Pollution Control Plant (OWPCP) was a secondary treatment plant handling one-third of San Francisco’s wastewater. The maximum treatment plant capacity was 65 million gallons per day, with an average daily dry weather flow of 17.5 million gallons. The facility was built in 1993 with 70 percent of the structure underground.
The objective of this project was to reconfigure the existing conventional single-stage anaerobic flow-through digestion process to a sequencing batch reactor, temperature anaerobic digestion process (SBR TPAD), replacing boilers, replacing the insulation and weather protection on the four existing digester vessels with closed-cell foam and tensioned fabric membrane, installing scum pumps and screening unit, and performing digestion process equipment improvements. The SBR TPAD upgrade was intended to produce a Class A biosolids product, which promoted sustainable heat recycling techniques and increased volatile solids reduction. The SBR TPAD system also contributed to bringing the OWPCP close to energy self-sufficiency.
The majority of the structure was underground, which created complexity for material handling. The biggest challenge was the logistics of performing the work within the existing OWPCP without affecting plant operations.