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The proposed apartment building is required to have mechanical ventilation systems or other means of <br />natural ventilation as required by the Uniform Building Code. Typical construction that complies with <br />the Uniform Building Code provides approximately 20 dBA of exterior to interior sound reduction. <br />Based on the noise analysis some of the proposed residential units would be exposed to exterior noise <br />levels that would require more than 20 dBA noise reduction. Therefore, upgraded window treatments <br />would be required to achieve the City required interior noise levels. Table 6 shows the calculated <br />exterior noise levels at each receptor site on the project along with the required exterior to interior noise <br />level reduction and the required window sound class transmission (STC) for windows of all residential <br />units that face Sunflower Avenue and Flower Street to meet the required interior noise level standard of <br />45 dBA CNEL. The City does not have exterior or interior noise standards for commercial land uses. <br />Therefore, window upgrades to reduce interior noise levels for the proposed non-residential amenities <br />on the site including the leasing office, mail room, fitness center, bike cafe, club room and business <br />center/conference room, parcel room are not required. <br />The following measure is recommended to reduce interior noise levels of the residential units that face <br />Sunflower Avenue and Flower Street to meet Santa Ana Municipal Code section 18-313. <br />Mitigation Measure No. 9 All residential units that face Sunflower Avenue and Flower Street shall <br />have acoustic windows with STC ratings shown in Table 6 of the Noise <br />Report.32 <br />Operational Noise Impacts <br />The operational activities associated with the proposed project have the potential to impact the nearby <br />school, multi -family attached residential dwelling units, and single-family detached residential dwelling <br />units. Specifically, these activities include parking lot noise and air conditioning units. <br />Land uses surrounding the site consist of an elementary school to the north, multi -family attached and <br />single-family detached residential dwelling units to the east, multi -family attached residential dwelling <br />units to the south (across Sunflower Avenue), and multi -family attached residential dwelling units to the <br />west (across Flower Street). The nearest existing sensitive receptors are the school playfields located <br />adjacent to the north and the multi -family attached residential dwelling units located adjacent to the <br />east. <br />Noise associated with parking lots includes, but is not limited to Idling cars/trucks, trucks diesel engines, <br />exhaust systems, trailer coupling, air brakes, warning signal, doors closing, and starting engine noise. <br />Noise levels associated with parking lots typically range between 44-63 dBA Ley at a distance of 100 <br />feet. <br />The City of Santa Ana Municipal Code Section 18-312 includes exterior noise level standards of 55 <br />dBA during the daytime (7:00 AM to 10:00 PM) and 50 dBA during the nighttime (10:00 PM to 7:00 <br />AM). In addition, Section 18-315 of the Municipal Code states that it is unlawful for any person to create <br />any noise which causes the noise level at a school while it is in use to exceed the noise limits as <br />specified in Section 18-312 prescribed for the assigned noise zone in which the school is located. <br />The proposed project includes the development of the site with 226 multi -family attached residential <br />dwelling units and an associated parking structure. This use is consistent with the surrounding <br />residential uses and would not cause a substantial permanent increase in ambient noise levels or <br />as Legacy Sunflower Project, Noise Impact Analysis, Gandinni, January 23, 2019. <br />Legacy Sunflower Apartments Page 83 <br />Mitigated Negative Declaration —March 14, 2019 <br />751-169 <br />