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CVFA Digester Gas Project,
Sacramento MUD, Elk Grove, CA

Water Works Engineers (WWE) was the design engineer and Overaa was the Construction Contractor for the Design-Build Digester Gas Delivery Project for the Sacramento Municipal Utility District (SMUD). SMUD implemented a digester gas cleanup project to optimize the energy recovered from up to 2500 scfm of digester gas produced at the Sacramento Regional Wastewater Treatment Plant (SRWWTP). The project was constructed at the Central Valley Financing Authority (CVFA) Power Plant in Elk Grove, California. The primary goal of the project is to remove hydrogen sulfide, siloxanes and moisture from the digester gas so that the gas meets the criteria of PG&E Rule 21 Section C.

Digester gas from SRWWTP is currently burned in the Heat Recovery Steam Generator (HRSG) duct burner at the CVFA Power Plant. Construction of the improvements resulted in the delivery of clean, dry digester gas, which is injected into a natural gas pipeline at approximately 600 psig that feeds the more efficient Consumnes Power Plant (CPP). The point of injection is a fenced-in yard located at the edge of the CVFA power plant boundary. The net energy generated by the digester gas cleanup project helps SMUD meet its renewable energy goals.

WWE services on the project included preparation of construction plans and specifications and assistance during construction phase. Major equipment design included iron sponges; refrigerant dryer; carbon filters (existing); post-compressor digester gas heat exchanger, desiccant dryers; analyzers, electrical, controls and instrumentation; and piping. Project included significant mechanical, electrical and civil design.

Refrigerant Dryer Skid with Iron Sponges in Background