Item 18 - Appeal Application Nos. 2023-02 and 2023-03 for Cabrillo Town Center project

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MWD's Weymouth Filtration Plant, which operates at approximately 42 percent capacity during the winter and 65 percent capacity during the summer. Additional development accommodated under the Overlay Zone would increase water use within the City, thus increasing the need for water treatment services. As discussed above, MWD can meet 100 percent of the City's imported water needs until at least the year 2030. Beyond that date, improvements associated with the State Water Project supply, additional local projects, water conservation, and additional water transfers may be needed to adequately serve the City. The Orange County Water District (OCWD), which provides the groundwater supply to the City, anticipates that there would be sufficient groundwater supplies to meet projected future demand requirements in Santa Ana. Implementation of the Overlay Zone would not require or result in the construction of new water treatment facilities or the expansion of existing facilities, and impacts would be less than significant. No mitigation is required. Wastewater Treatment Implementation of the Overlay Zone would generate additional demand on the existing sewer system from increased sewage flows. New residential, commercial and office growth would generate wastewater that would require treatment. As described in the Existing Conditions section, wastewater service within the Overlay Zone area is provided by the City and the Orange County Sanitation District (OCSD). Wastewater from the City's system and OCSD is treated by the OCSD at their two treatment plants. The OCSD Treatment Plant No. 1 maintains a design capacity of 174 mgd and treats on average a flow of 90 mgd. Treatment Plant No. 2 maintains a design capacity of 276 mgd and treats on average a flow of 153 mgd. Plant No. 1 and Plant No. 2 are operating at 52 percent and 55 percent of design capacity, respectively. Therefore, each of the treatment plants serving the City is operating below their design capacity. The additional 1.106 mgd of wastewater, as stated above under Impact 4.13-4, would be distributed between OCSD Treatment Plant No. 1 and Treatment Plant No. 2. Each of these plants has the capacity to treat the full increase in sewage from the Overlay Zone. To illustrate the most conservative analysis, if the entire Overlay Zone's wastewater went to Treatment Plant No. 1, its average flow would increase to approximately 91 mgd, an increase of 1.1 percent, and the plant would still operate below its design capacity. If the entire City's sewage were directed to Treatment Plant No. 2, its average flow would increase to approximately 154 mgd, an increase of 0.6 percent, and the plant would operate below its design capacity. Because increased wastewater due to implementation of the proposed General Plan Update could be accommodated within the existing treatment infrastructure, expansion would not be required. Therefore, impacts to the wastewater treatment facilities associated with increased growth in the City would be less than significant, and no mitigation is required. OCSD maintains certain trunk sewer lines that may require expansion on an as needed basis due to incremental increases in sewage generation as a result of a new development. The City would also maintain local sewer lines and upgrades as part of individual projects. Implementation of Mitigation Measure MM-OZ 4.13-1 would ensure that any new development within the Overlay Zone does not result in an exceedance of an existing sewer conveyance capacity for City and OCSD facilities, and impacts would be less than significant. Cabrillo Town Center City of Santa Ana Technical Memorandum August 2023 City Council 18 — 639 10/3/2023