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("„ hI Mo Town C:^ nt � 13A of vti, Saantis. Ana Its v« w of I nv�mnm ntal NoNe A naly[�N Page 4 of b .kdfie 29, 2023 definition of the "high noise -producing activities," which should cease at 5PM, or the amount of reduction required to be achieved by noise barriers/blankets around equipment. OPERATIONAL IMPACTS HVAC Equipment Noise The MEMU EIR includes an analysis of HVAC noise associated with new developments in the overlay zone, starting on page 4.9-19. The calculation starts with the assumption that HVAC systems "can result in noise levels that average between 50 and 65 dBA, Leq at 50 feet from the equipment', then reasons that shielding around rooftop equipment might typically be expected to provide 15 dBA of noise reduction, resulting in a net noise level at 50-feet of 50 dBA. For equipment that runs 24- hours per day, the preparers point out that the relationship between the Leq noise level and the CNEL is 6.7 dBA, so that an Leq of 50 dBA at 50-feet would equate to a CNEL of 57. And since 57 CNEL falls below the proposed 65 CNEL significance threshold, the EIR concludes that HVAC noise is less than significant. • We see two problems with this calculation and less -than -significant conclusion: - Firstly, the estimate of HVAC unit noise seems too low for a mixed -use project that will likely have hundreds of HVAC units operating simultaneously. This is because the combined effect of multiple similar noise sources grouped together is calculated from the equation: Total Noise Level = Noise Level for Single Source x 10*LOG10 (Number of Sources) So, while we would expect that a single AC unit, serving a single apartment could produce a noise level of approximately 55 dBA at 50-feet, a grouping of 100 units (for example serving one section of the building) would have a total noise level of 55 + 10*LOG10 (100) = 75 dBA at 50- feet. Larger, commercial -grade equipment associated with the commercial and office portions of the project as well as ventilation fans for the parking structure (if required) would likely produce more noise than residential AC units, further adding to the noise sum for surrounding receivers. It is therefore likely that the analysis in the MEMU EIR substantially underestimates the total HVAC noise impact of the project. The second problem with the HVAC noise analysis in the MEMU EIR is that (like the proposed thresholds of significance) it overlooks the noise limits in the Santa Ana Municipal Code. The SAMC requires that noise from continuous sources — such as HVAC equipment — be limited to 50 dBA at night, unless the ambient noise level on the receiving property is greater than 50 dBA, in which case the ambient noise level becomes the noise limit. We expect that nighttime ambient noise levels on much of the Lake Dianne property are less than 50 dBA, so that the allowable limit for the combined noise of all HVAC equipment associated with the project is 50 dBA, not CNEL 65 as the MEMU EIR suggests. • For these reasons, we believe that the analysis presented in the MEMU EIR does not adequately demonstrate that HVAC noise associated with the Cabrillo Town Center project will be less than significant. Outdoor Amenities • The Cabrillo Town Center project would include a significant amount of active and passive open space and outdoor amenities, including a 7,500 square -foot roof terrace, which would accommodate uses such as outdoor dining, game terrace, and view deck.