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City of Pleasanton 2023-2031 (6th Cycle) Housing Element Update Errata Final EIR 3-30 FirstCarbon Solutions https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480022/EIR/4 - Final EIR/21480022 Sec03-00 Errata.docx Wastewater Treatment The RWTF handles wastewater from the city (aside from the wastewater from the Ruby Hills housing development, which is treated at the LWRP). The City currently owns 8.5 mgd of secondary treatment capacity from the RWTF. The RWTF includes secondary, tertiary, and advanced recycled water treatment facilities. The current average dry-weather wastewater- flow design capacity of the secondary treatment facilities is 17 mgd with an ultimate required capacity of 20.7 mgd at buildout of the 2020 UWMP in 2045. 10.4 mgd of this influent is projected to originate from the DSRSD service area and the remaining 10.3 mgd of influent is projected to originate from the city. DSRSD RWTF is permitted to operate the secondary treatment facilities up to 17 million gallons per day on average dry weather flow. A permit change for the secondary treatment facilities will be required for DSRSD to increase the secondary treatment capacity to treat additional influent flow at buildout (2045). Conventional secondary treatment methods include primary sedimentation, activated sludge secondary treatment, chlorine disinfection, and effluent pumping. A portion of the secondary effluent undergoes the tertiary treatments of sand filtration and ultraviolet (UV) disinfection, which has a treatment capacity of 16.2 mgd. Backup facilities exist to handle times of low or high demand, with a capacity of 3 mgd. Page 3.15-35, Third Full Paragraph In response to ZONE 7-4, the following paragraph has been revised: Water Supply and Groundwater Contamination As described above, because of PFAS contamination in the city’s groundwater, the City has determined that all groundwater supply wells for the city may be taken out of commission no later than the first quarter of 2023. Currently, groundwater makes up approximately 20 percent of the total water supply for the City, and, if the existing groundwater supply wells are taken out of commission, this 20 percent will not be available to the City without treatment or additional supply sources. Zone 7 has not identified any impacts to Zone 7’s water supply for the city as a result of the elevated pollutants of concern in groundwater. However, as state regulations concerning PFAS continue to evolve, they have the potential to impact ZONE 7’s well production, similar to the City’s groundwater supply. The City will continue to coordinate with Zone 7 regarding impacts to Zone 7 groundwater supply associated with PFAS. The elevated pollutant level in the city’s groundwater supply directly affects water supply available from local groundwater supply wells for any development application consistent with the Housing Element Update. The City’s total projected water supply minus the approximate 20 percent groundwater supply is shown in Table 3.15-8 for the years 2023, 2024, 2025, 2030, 2035, 2040, and 2045. These updated values represent the projected water supply available for the City after decommission of the groundwater wells. Page 3.15-36, First Paragraph In response to ZONE 7-5, the following paragraph has been revised: