Water+ Treatment Plants Resiliency and Improvements Project Addendum

Water+ Treatment Plants Resiliency and Improvements Project Addendum

The project consists of significant improvements at both of the City's drinking water treatment plants: Sacramento River Water Treatment Plant (SRWTP), located north of downtown, and E. A. Fairbairn Water Treatment Plant (FWTP), located east of Sacramento State University. These improvements replace critical treatment infrastructure past its useful life, improve resiliency to address environmental and regulatory changes impacting drinking water, and increase the drinking water treatment capacity at the Sacramento River Water Treatment Plant in order to ensure sufficient water supply to support projected water use increases through 2050. The initial phase would improve treatment reliability by replacing facilities at the end of their effective lives. This phase of work would also provide treatment resiliency through the addition of ozone treatment to both the E. A. Fairbairn Water Treatment Plant (FWTP) and the Sacramento River Water Treatment Plant (SRWTP). In parallel with the initial reliability and resiliency improvements at both water treatment plants, the SRWTP raw-water supply and treatment capacity would be increased from 160 million gallons per day (MGD) to 235 MGD. Timing of the components of this phase will depend on available funding and project timing. Additional phases would be staged to meet the increasing City potable water demand through 2050 for an ultimate capacity of3 IO MGD at the SRWTP. No expansion of treatment capacity at the FWTP would be implemented due to limitations placed on withdrawal amounts from the American River. Specifically, implementation of the proposed project would involve the following components: • Replacement of aging infrastructure at both FWTP and SRWTP; • Integration of ozone into the treatment process at both FWTP and SRWTP; • Conversion from chlorine gas to sodium hypochlorite as the primary chemical for disinfection of the water at both FWTP and SR WTP; • Construction and operation of a secondary intake in the Sacramento River and pipelines for transferring water to SR WTP; • Expansion of existing treatment processes at SR WTP to accommodate the additional capacity (including the grit basins, flocculation and sedimentation basins, filtration, and finished water storage); • Installation of pipe Iines between the existing Sacramento River Intake and the replacement intake and SRWTP; and • Improvement of the water transmission and distribution system in the vicinity of SRWTP to address critical hydraulic constrictions. Since certification of the EIR and project approval, the City proposes changes to the approved project that include an expansion of the existing eastern boundary of the SRWTP property to incorporate an adjacent City-owned parcel (Assessor Parcel Number 00 l-0061-026-0000), approximately two acres in size. The proposed changes also include the relocation, construction and operation of the new gravity thickeners infrastructure at this new area. The new gravity thickeners would be moved to the new area to provide additional space between this infrastructure and to improve access. The new area would include hardscape to accommodate the gravity thickeners and support maintenance activities. In addition, new vegetated areas or swales would be established along the perimeter of the new area to provide stormwater management. No new treatment infrastructure is proposed to be constructed and operated at the SRWTP. All other components of the approved project remain unchanged.

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Citywide, Northern California

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