2019-090 - Adopting the Mitigated Negative Declaration

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*:/ : 11-1 h WA of the project is no longer a required topic for impact evaluation under CEQA. Nonetheless, for the complete understanding of the public, it is noted that the project areas are not located within the 65 dBA CNEL contour per the City of Santa Ana's Noise Element, Exhibit 5, Transportation Noise Sources. However, no determination of significance is required. Skate Area Noise As described above, projectgeneratedoperational noise would not exceed City noise standards. However, implementation of the project has the potential to create an increase in ambient noise levels. Changes of 1 to 3 dBA are detectable under quiet laboratory conditions and changes of less than 1 dBA are usually indiscernible. A 3 dBA change in noise levels is considered the minimum change that is detectable with human hearing in outside environments. A change of 5 dBA is readily discernable to most people in an exterior environment whereas a 10 dBA change is perceived as a doubling (or halving) of the sound. The results of noise monitoring at ST-4 indicate that existing ambient noise levels are approximately 46 dBA L50 at the 60 Street Site during evening hours. Since a change of 5 dBA would be considered readily discernable, this is used as the threshold for potentially significant impacts. The results of ST-2 and ST-3 measurements indicate that L5o noise levels are approximately 54 dBA 5 — 25 feet from the edge of the skate area. The nearest residences to the proposed skate area are approximately 5 feet to the west and southwest. The existing garages on the southern property line would reduce noise levels by at least 5 dBA by breaking line -of -sight, resulting in noise levels of 49 dBA L5o at the residences to the south, which would not create an ambient noise increase of 5 dBA L5o or more. The single story residences immediately adjacent to the west and the two-story apartments immediately adjacent to the southwest could be exposed to ambient noise level increases of up to 8 dBA L50, which is considered potentially significant. Therefore, Mitigation Measure N0ISE-1, which provides two options, would be required to reduce this impact to a level of less than significant. Although noise from the skate area would be readily discernable from the adjacent residential uses, the noise increase would not be considered a substantial permanent increase in ambient noise levels in the vicinity given that the skate park operating hours would be restricted to 8 PM under MM NOI-1. Provided that skating area is closed by 8 PM, when residences are reasonably anticipated to conduct normal household activities, not before typical quiet hours to begin (e.g., 10 PM), even though some residences to the west and southwest could be exposed to ambient noise level increases of up to 8 dBA L5o, it would not be considered a substantial permanent increase. It should also be noted that Section 18.314 of the City's Noise Ordinance specifically excludes noise from activities conducted at any park or playground owned and operated by a public entity. Therefore, with mitigation, impacts would be considered less than significant. Alternatively, a 10-foot noise barrier wall could be constructed along the western and southern boundary to block the line of sight from the western and southwestern residences. With the minimum 10-foot barrier, the ambient noise increase is predicted to be reduced by at least 5 dBA. Therefore, the ambient noise increase would be reduced to 49 dBA L5o or less (i.e., up to 3 dBA increase). Therefore, compared to existing ambient noise levels of approximately 46 dBA L5o, the proposed project would not cause ambient noise levels to increase by 5 dBA or more (readily discernable to most people). Implementation of MM N0I-1 would ensure that impacts are reduced to a less than significant level. 75C-115