31B - CUP - 1901 NORTH FAIRVIEW ST

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C €ty of Santa Ana Environmental Checklist Table 3 -18 provides the modeled noise levels for modeled receivers for opening year (2013) plus Phase 1, and opening year (2019) plus Phase Il scenarios for onsite receivers. Existing noise levels were not calculated because there are no existing onsite noise - sensitive receivers in the existing vacant condition. Table 3 -18. Exterior Modeled Noise levels from Fairview Street on Project Facilities Receivers M -1 through M -3 are the proposed residential patio locations that would be developed as part of the project. The residential patio locations are directed toward the central portion of the project site, and will receive noise shielding from the proposed building structures between the patios and Fairview Street. As shown in Table 3 -17, the noise model confirms that the proposed exterior residential uses would not exceed the City's 65 dBA exterior CNEL threshold. As a result, Fairview Street - related traffic noise impacts to the exterior residential areas would be less than significant. However, the building elevations that face Fairview Street will likely exceed the exterior threshold of 65 dBA CNEL, and this will likely cause the interior standard of 45 dBA CNEL to be exceeded. Similarly, Receiver M -4 is the location of Building G that is proposed to be used for classrooms. The modeled noise level at the far ade of the classroom building is approximately 73 dBA CNEL. Because no outside uses are planned at this location on the project site, the 65 dBA CNEL exterior threshold would not apply. However, assuming a 20 dBA insertion loss between exterior and interior environments, the interior noise level within the classrooms would be approximately 53 dBA CNEL, which exceeds the City's General Plan 45 dBA CNEL interior threshold. As a result of this threshold exceedance, Mitigation Measure N01 -2 is included to reduce the interior noise levels to a less -than- significant level. Mitigation Measure N01 -2: All residential and classroom /library units that face Fairview Street will be fitted with acoustically rated windows (minimum Sound Transmission Class rating of 35) to reduce exterior /interior noise transmission. Additionally, any residential doors with a direct exposure to Fairview Street will meet a minimum STC rating of 35 and be fitted with tight seals, and vents and ventilation openings will be designed to ensure that the interior noise levels of the habitable rooms do not exceed 45 dBA CNEL. Operational Noise ( Onsite Uses) Project Site Equipment Noise. The project site is currently vacant and undeveloped, and no noise is generated from its existing condition. As part of the operation of the project, heating, ventilation, I ne Academy Charter High School June 2012 Initial Study /M €tigated Negative Declaration 3 -77 ICF 00914.11 31 B -155 Modeled Opening Modeled Opening Year (2013) plus Year (2019) plus Project Noise Level Project Noise Receiver Receiver Location (dBA CNEL) Level (dBA CNEL) M -1 Building B outside family patio 59 60 M -2 Building A outside family patio 59 59 M -3 Building D outside family patio 55 55 M -4 Building 6 classrooms 73 73 Receivers M -1 through M -3 are the proposed residential patio locations that would be developed as part of the project. The residential patio locations are directed toward the central portion of the project site, and will receive noise shielding from the proposed building structures between the patios and Fairview Street. As shown in Table 3 -17, the noise model confirms that the proposed exterior residential uses would not exceed the City's 65 dBA exterior CNEL threshold. As a result, Fairview Street - related traffic noise impacts to the exterior residential areas would be less than significant. However, the building elevations that face Fairview Street will likely exceed the exterior threshold of 65 dBA CNEL, and this will likely cause the interior standard of 45 dBA CNEL to be exceeded. Similarly, Receiver M -4 is the location of Building G that is proposed to be used for classrooms. The modeled noise level at the far ade of the classroom building is approximately 73 dBA CNEL. Because no outside uses are planned at this location on the project site, the 65 dBA CNEL exterior threshold would not apply. However, assuming a 20 dBA insertion loss between exterior and interior environments, the interior noise level within the classrooms would be approximately 53 dBA CNEL, which exceeds the City's General Plan 45 dBA CNEL interior threshold. As a result of this threshold exceedance, Mitigation Measure N01 -2 is included to reduce the interior noise levels to a less -than- significant level. Mitigation Measure N01 -2: All residential and classroom /library units that face Fairview Street will be fitted with acoustically rated windows (minimum Sound Transmission Class rating of 35) to reduce exterior /interior noise transmission. Additionally, any residential doors with a direct exposure to Fairview Street will meet a minimum STC rating of 35 and be fitted with tight seals, and vents and ventilation openings will be designed to ensure that the interior noise levels of the habitable rooms do not exceed 45 dBA CNEL. Operational Noise ( Onsite Uses) Project Site Equipment Noise. The project site is currently vacant and undeveloped, and no noise is generated from its existing condition. As part of the operation of the project, heating, ventilation, I ne Academy Charter High School June 2012 Initial Study /M €tigated Negative Declaration 3 -77 ICF 00914.11 31 B -155