75B - PH - BRISTOL EIR FR CIVIC CENTER TO WASHINGTON(no exhibit 1)

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ENVIRONMENTAL IMPACT REPORTADDENDUM Bristol Street Widening Phase IIIA — Civic Center Drive to Washington Avenue of Bristol Street from Civic Center Drive to Washington Avenue to address existing and projected traffic congestion. Increases in roadway capacity would result in improvement in the LOS along Bristol Street. The improvement in LOS would result in increases in average vehicle speed and reductions in the amount of delay vehicles experience at intersections thereby resulting in both lower emissions and lower emissions rates associated with higher vehicle speeds. As such, the Project would continue to result in a beneficial impact. Implementation of the proposed Project would not result in greater impacts than previously analyzed in the 1990 FEIS /EIR. Mitigation Measures No additional new mitigation measures are required. d.) Expose sensitive receptors to substantial pollutant concentrations? A project could have the potential to expose sensitive receptors to elevated pollutant concentrations if it would cause or contribute substantially to elevated pollutant concentration levels or place the Project in an area with elevated pollutant concentrations. An evaluation of air pollutant emissions as it affects local sensitive receptors has been conducted for both the construction and operations phases of the Project. Localized Construction Impacts Localized air pollutant emissions are evaluated relative to the exposure of local sensitive uses to air pollutant concentrations generated by the proposed Project. These are pollutant concentrations which can be directly correlated to the health -based ambient air quality standards. This differs from regional emissions which were discussed previously in that regional emissions are used to assess how much air pollution is generated within an air basin and does not have a direct correlation with health effects. Localized Significance Thresholds (LSTs) have been developed by the SCAQMD for nitrogen oxides (NOx), carbon monoxide (CO), PMIo, and PM2.5• The LSTs determine whether project - related emissions would substantially contribute to or exceed the ambient air quality standards and expose sensitive receptors to excessive concentrations of air pollutants. The LSTs differ based on distance such that a greater allowance in air pollutant emissions is allowed for construction activities occurring further from a sensitive use and a lesser allowance in emissions is given for construction activities occurring closer to sensitive uses. Only short -term emissions occurring at the Project site for the Project's construction phase were included to determine if sensitive receptors local to the Project site would be adversely affected. Emissions generated by construction activities disperse rapidly with distance from the construction site. Individual construction phases were compared against the SCAQMD's LST significance criteria. As shown in Table 5, Project emissions would not exceed the EST screening level criteria for CO, nitrogen dioxide (NO2), PMIO, or PM2.5• Because emissions associated with this alternative would be less than the LST, onsite construction emissions would not be expected to exceed the federal or California AAQS at the nearest sensitive receptors. As such, no significant air quality impacts related to localized air pollutants would occur from the construction phase. TABLE 5 LOCALIZED SIGNIFICANCE THRESHOLDS ANALYSIS FOR CONSTRUCTION ACTIVITIES TRUCTION PHASE Demolition NOx 66 41 60 34 ANA 305 -011 (PER 02) CITY OF SANTA ANA (01/19/2015) YU 75B -52 CO PMI0 PM2.s