The 2006 Water Treatment and Transmission Improvement Program (WTTIP) EIR identified improvements to water treatment processes at the Orinda Water Treatment Plant (WTP). Due to changes in the identified improvements and in conformance with CEQA, the Project prepared a Supplemental EIR to the WTTIP EIR. The Project includes demolition of an existing maintenance building and construction of a new disinfection facility comprised of a new above-ground two-story maintenance and ultra-violet electrical (MAUVE) building with a below-grade UV structure and a below-grade chlorine contact basin (CCB), two electrical buildings, a standby generator, pipelines and vaults, and other supporting facilities. The MAUVE building with UV structure and the CCB would be adjacent and fully integrated facilities. Maintenance activities and associated uses previously housed in the existing maintenance building that will be demolished will be incorporated into the Project disinfection facility and grounds maintenance building with associated parking at the Orinda WTP site. The Project will also install landscaping around the Orinda WTP perimeter, remove vegetation, replace existing and install new security fencing, and restore the site following construction.