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

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noise impacts from rooftop mechanical equipment on nearby sensitive receptors would be negligible. First, most modern heat pumps are relatively quiet, with sound ratings of up to 60 decibels, equivalent to normal human conversation. Second, there would be no line -of -sight from these rooftop units to the sensitive receptors. Because the sensitive uses near the Project Site are one- to three -stories in height, there would be no sound path from the mechanical equipment to receptors that would be 20 to 45 feet lower than the roof of the Project. Third, the presence of the Project's roof edge creates an effective noise barrier that further reduces noise levels from rooftop HVAC units by 8 dBA or more. A parapet would further shield sensitive receptors near the Project Site. These design elements would be helpful in managing noise. For the townhomes, outdoor mechanical equipment for heating and cooling for each residence would likely be located on the ground level of each unit. This could include a ground -mounted heat pump that would generate noise during both heating and cooling sessions while air conditioners operate during cooling cycles. This equipment would include a number of sound sources, including compressors, condenser fans, supply fans, return fans, and exhaust fans. These units could be rated to generate a sound power between 51 and 76 dBA. Any off -site sensitive receptors would not experience elevated noise levels without a direct line -of -sight to these units. Given their location near each residence, any sound path from these units would be attenuated by the presence of the townhomes and structures in the Project, as well as the distance to off -site receptors (i.e., Cabrillo Park to the north, Lake Dianne Apartments to the northeast). As a result, noise from HVAC units would negligibly elevate ambient noise levels, far less than the 5 dBA CNEL threshold of significance for operational impacts. Regarding potential impacts related to composite outdoor uses, Exhibit 9F explains that the primary use of these spaces would be for human conversation, which would produce negligible noise increases. There are no amplified noise sources proposed at the Project. Vocal intensity increases about 0.38 dB for every 1.0 dB increase in noise levels above 55 dB. For example, the sound of a human voice at 60 dB would produce a noise level of 39 dB at ten feet, which would not elevate ambient noise levels at any of the analyzed sensitive receptors by more than 0.2 dBA Leq. Moreover, noise levels from human speech would attenuate rapidly with greater distance, resulting in a 33 dB noise level at twenty feet, and 27 dB at 40 feet. Table 9 in Exhibit 9F Resolution No. 2023-xx f 24 City Council 18 — 338 10/ 3