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ͭͲͱͱʹ-ͬͰ Noise Memo.docx ͱ Warner Avenue Footlab NOISE PREDICTION MODEL To fully describe the exterior operational noise levels from the Project, Urban Crossroads, Inc. developed a noise prediction model using the CadnaA (Computer Aided Noise Abatement) computer program. CadnaA can analyze multiple types of noise sources using the spatially accurate Project site plan, georeferenced Nearmap aerial imagery, topography, buildings, and barriers in its calculations to predict outdoor noise levels. Using the ISO ͵Ͳͭͯ-ͮ protocol, CadnaA will calculate the distance from each noise source to the noise receiver locations, using the ground absorption, distance, and barrier/building attenuation inputs to provide a summary of the noise level at each receiver and the partial noise level contributions by noise source. The noise level calculations provided in this noise assessment account for the distance attenuation provided due to geometric spreading, when sound from a localized stationary source (i.e., a point source) propagates uniformly outward in a spherical pattern. A default ground attenuation factor of ͬ.ͱ was used in the CadnaA noise analysis to account for mixed ground representing a combination of hard and soft surfaces. OPERATIONAL NOISE ANALYSIS This section analyzes the potential stationary-source operational noise impacts at the nearby receiver locations resulting from the operation of the proposed Warner Avenue Footlab Project. OPERATIONAL NOISE STANDARDS The City of Santa Ana noise control guidelines for determining and mitigating non-transportation or stationary noise source impacts from operations in neighboring residential areas are found in the Municipal Code [Section ͭʹ-ͯͭͮ]. Section ͭʹ-ͯͭͮ indicates, “The following noise standards, unless otherwise specifically indicated, shall apply to all residential property within a designated noise zone.” The performance standards found in Section ͭʹ-ͯͭͮ limit the exterior noise level to ͱͱ dBA Leq during daytime hours (ͳ a.m. – ͭͬ p.m.) and ͱͬ dBA Leq during nighttime hours at residential receiver locations The City of Santa Ana noise ordinance is included in Appendix A. OPERATIONAL NOISE SOURCES The Project-related exterior noise sources are expected to include roof-top air conditioning units, trash enclosure activity, and parking lot vehicle movements. To estimate the Project operational noise impacts, reference noise level measurements were collected from similar types of activities to represent the noise levels expected with the development of the proposed Project. While sound pressure levels (e.g., Leq) quantify in decibels the intensity of given sound sources at a reference distance, sound power levels (Lw) are connected to the sound source and are independent of distance. Sound pressure levels vary substantially with distance from the source and diminish because of intervening obstacles and barriers, air absorption, wind, and other factors. Sound power is the acoustical energy emitted by the sound source and is an absolute value that is not affected by the environment. The Project reference operational and sound power levels are summarized below in Table ͭ. The reference project operational noise levels are based on the Project-related noise source activities shown in Exhibit Ͱ.