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

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VdB at a distance of 25 feet. Like noise, groundborne vibration will attenuate at a rate of approximately 6 VdB per doubling of distance. The groundborne vibration generated during construction activities would primarily impact existing sensitive uses (e.g., residences, schools, and hospitals) that are located adjacent to, or within, the vicinity of specific projects. These sensitive uses could sometimes be located as close as 25 feet to the construction site or as far as several hundred feet away. Vibration levels could reach up to 87 VdB at sensitive uses located within 25 feet of construction. For sensitive uses that are located at or within 25 feet of potential project construction sites, sensitive receptors (e.g., residents, school children, and hospital patients) at these locations may experience vibration levels during construction activities that exceed the Federal Transportation Administration's (FTA) vibration impact threshold of 85 VdB for human annoyance. So long as construction occurs more than 50 feet from sensitive receptors, the impact associated with groundborne vibration generated by the equipment would be below 85 VdB and thus would be less than significant. However, as specific site plans or constructions schedules are unknown at this time, it may be possible that construction activities could occur as close as 25 feet from sensitive receptors. This would result in these sensitive receptors experiencing vibration impacts above the threshold of 85 VdB, in which case this impact would be potentially significant. Implementation of Mitigation Measures MM-OZ 4.9-1 through MM-OZ 4.9-4 would help to reduce this impact, but not to a less -than -significant level. Therefore, it was determined that this impact would remain significant and unavoidable. During operation of the Overlay Zone, background operational vibration levels would be expected to average around 50 VdB, as discussed previously in this section. This is substantially less than the 85 VdB threshold for people in the vicinity of the project site. Groundborne vibration resulting from operation of the Overlay Zone would primarily be generated by trucks making periodic deliveries to the Overlay Zone. However, these types of deliveries would be consistent with deliveries that are made along roadways to commercial uses in the Overlay Zone and in the Overlay Zone vicinity and would not increase groundborne vibration above existing levels. Because no substantial sources of groundborne vibration would be built as part of the Overlay Zone, no vibration impacts would occur during operation of the Overlay Zone. Therefore, operation of the Overlay Zone would not expose sensitive receptors on or off site to excessive groundborne vibration or groundborne noise levels, and this impact was determined to be less than significant. Airport Noise The Certified EIR stated that the Overlay Zone is not located within an airport land use plan or within 2.0 miles of a public airport or public use airport. The nearest public airport to the project is the John Wayne Airport, which is located approximately 6.5 miles southwest of the Overlay Zone. Further, the Overlay Zone is located over 5,000 feet from the 60 CNEL noise contour for John Wayne Airport. Thus, no impact related to the exposure of people residing or working in the project site to excessive airport -related noise levels is anticipated. Cabrillo Town Center City of Santa Ana Technical Memorandum August 2023 City Council 18 — 600 10/3/2023