Construction of a new power generation and heat recovery building that allows the City of Santa Rosa to produce 4,400 KW of green energy through cogeneration. The new facility includes four spark ignited, high efficiency digester gas combustion engine generators, 12.47 KV paralleling switchgear, an electrical room, offices, and maintenance space. Scope also covered the design and construction of digester gas cleanup systems which provide siloxane, moisture, and H2S removal along with additional gas compression to support the gas blending system. Overaa self-performed the concrete, piping and equipment installations, functional testing and commissioning. We scheduled the project to maintain full operational capacity of the existing cogeneration plant during construction, utility tie-ins, start-up, and commissioning.