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DENVER — CH2M HILL and the San Francisco Public Utilities Commission (SFPUC) earned the California Association of Sanitation Agencies (CASA) Technological Innovation and Achievement award for the joint concept development and final design of a sequencing batch reactor temperature phased anaerobic digestion (SBR TPAD) system for the Oceanside Water Pollution Control Plant (OSP) in San Francisco. The CASA awards recognize exceptional public clean water services, programs, and projects demonstrating industry-leading innovations that may serve as examples for other agencies to follow.

“We are proud to not only be recognized alongside SFPUC with the CASA Technological Innovation and Achievement award, but to also be working in close partnership with SPFUC on this important project,” remarked Dave Green, CH2M HILL Project Manager. “SFPUC has shown terrific foresight in meeting the long-term needs of their community and their ratepayers, and this project is a great example of how the organization is working to adhere to changing biosolids regulations while minimizing capital expenditures and expediting construction.”

In the late 1980s, CH2M HILL designed the original OSP, a high-purity oxygen secondary plant serving the west side of San Francisco. The treatment plant relies upon a conventional mesophilic, flow-through anaerobic digestion to treat approximately 30 percent of San Francisco’s biosolids that are land applied during the dry season (April through October). In order to meet new requirements for Class A biosolids treatment for land application in Solano County, SFPUC and CH2M HILL worked hand-in-hand to develop SBR TPAD to upgrade the previous model for the production of Class A biosolids while minimizing overall construction costs and maximizing the value of the existing facilities.

Intended to produce a Class A biosolids product, the SBR TPAD system works to promote sustainable heat recycling techniques, and increase volatile solids reduction to 64 percent. In addition to the solids produced from the wastewater treatment process, the SBR TPAD upgrades are designed to co-digest up to 30,000 gallons of grease trap waste per day that the plant receives from local haulers. The combined efforts of the co-digestion process and the SBR TPAD system are targeted to increase biogas production significantly, bringing OSP close to energy self-sufficiency via their combined heat and power systems.

The SBR TPAD project represents effective collaboration between CH2M HILL and SFPUC to successfully develop an innovative solution that can now be replicated by other wastewater treatment facilities without considerable changes to existing operation and maintenance. With the final design now complete, construction of the system is expected to begin this fall.