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4.8 Nolse this time, it may be possible that construction activities could occur as close as 25 feet from sensitive receptors. This would result in these sensitive receptors experiencing vibration impacts above the threshold of 85 VdB, in which case this impact would be potentially significant. Implementation of mitigation measures MM4.8-1 through MM4.8-4 would help to reduce this impact, but not to a less -than - significant level; therefore, this impact would remain significant and unavoidahle. 4.8.4 Cumulative Impacts The geographic context for the analysis of cumulative noise impacts depends on the impact being analyzed. For construction impacts, only the immediate area around the project site would be included in the cumulative context. For operational/roadway related impacts, the context is existing and future development in the City of Santa Ana. This cumulative impact analysis considers development of the proposed project, in conjunction with ambient growth and other development within the vicinity of the proposed project in the City of Santa Ana. Noise is by definition a localized phenomenon, and significantly reduces in magnitude as distance from the source increases. The analysis accounts for all anticipated cumulative growth within this geographic area, as represented by full implementation of the City of Santa Ana General Plan Framework and development of the related projects provided in 'Table 3-3 in Chapter 3.0 (Project Description). Increases in noise at sensitive uses would occur as a result of construction of individual projects pursuant to the Transit Zoning Code the proposed project, along with other construction in the vicinity. Other construction that may occur in the vicinity of the Transit Zoning Code area would contribute noise levels similar to those generated by individual development projects. Where this development adjoins a proposed project's construction, the combined construction noise levels would have a cumulative effect on nearby sensitive uses. Noise is not strictly additive, and a doubling of noise sources would not cause a doubling of noise levels; however, cumulative construction noise levels would be in excess of 65 dBA CNEL at nearby sensitive receptors. As discussed under Impact 4.8-1, Section 18-314(e) of the City Municipal Code limits construction activities to between the hours of 7:00 A.M. and 8:00 P.M. Monday through Saturday, and also prohibits construction activities on Sundays and public holidays. Because compliance with this construction time limit is required by the City Municipal Code, the proposed project and all other cumulative development would be exempt, and the cumulative impact associated with construction noise in the Santa Ana area would be considered less than significant. Similarly, because construction -related noise generated under the proposed project would be exempt from established noise standards, the construction of the proposed project would not be cumulatively considerable and the cumulative impact of the project would also be less than significant Other development projects within the City of Santa Ana could potentially introduce residential development into areas that currently exceed the 60 dBA CNEL standard for residential uses. However, such residential development would have to be constructed so that noise levels within exterior living spaces do not exceed the 65 dBA CNEL standard as set forth in the Noise Element of the General Plan. Since any potential new residential development within the City would be required to mitigate through site and building design, insulation and other noise preventative measures, the proposed project's impact City of Santa Ana Transit Zoning Code (SD 84A and SD 848) EIR 4.839