55C - RESO - BRISTOL ST IMPROVEMENTS

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ENVIRONMENTAL IMPACT REPORT ADDENDUM Bristol Street Widening Phase IIIB — Washington Avenue to 17" Street trenching, paving, and development of ancillary structures. During construction activities, emissions from heavy equipment exhaust, delivery trucks, and fugitive dust would be generated for a short duration. To accurately determine the significance of air quality impacts from construction activities, construction emissions are quantified and compared to the significance thresholds set by the SCAQMD. Project- specific data, such as construction timelines and dimensions of the Project site, along with general operating guidelines, were used as inputs to the SCAQMD's California Emissions Estimator Model (CalEEMod) (version 2011.1.1) to quantify construction emissions. As shown in Table 2, emissions calculated by this model were compared to the SCAQMD's regional significance thresholds to determine whether project emissions would result in a significant air quality impact. As shown in Table 2, emissions attributable to construction of the proposed Project were found to be below the significance thresholds adopted by the SCAQMD for all the analyzed air pollutants. Because emissions were found to be below the SCAQMD's significance thresholds, Project related construction emissions are not considered by the SCAQMD to result in a significant air quality impact. In addition, mitigation measures included in the 1990 FEIS/EIR would further reduce construction- related air quality impacts. TABLE 2 PROJECT RELATED CONSTRU Demolition voc NOx CO S02 PM10 P102.e 9 70 44 <1 12 3 Trenching 5 41 19 <1 2 2 Grading 8 60 34 <1 6 4 Paving 3 16 11 <1 2 1 Maximum 9 70 44 <1 12 4 SCAQMD Threshold 75 100 550 150 150 55 Exceeds Threshold? No No No No No No Source: Air Quality Assessment Report (URS 2013a). Notes: VOC = volatile organic compounds; NOx = nitrogen oxides; CO = carbon monoxide; S02 = sulfur dioxide; PMio = particulate matter less than less than or equal to 10 microns in diameter; PM2,6 = particulate matter less than less than or equal to 2.5 microns in diameter. An assessment of regional emissions associated with the operations phase of the proposed Project was also conducted which compared emissions with and without the proposed Project. Air pollutant emissions generated by roadway vehicles are quantified based on emissions rates that vary based on vehicle speed. Because the proposed Project would increase the roadway capacity along Bristol Street, traffic congestion would be alleviated and average vehicle speeds would increase along improved roadway segments. Table 3 shows the emissions that would occur with and without the proposed Project based on the average vehicle speeds. As shown in Table 3, air pollutant emissions would be less under the With- Project Alternative as opposed to the No Project Alternative due to the lower emission rates associated with higher average vehicle speeds. The SCAQMD has established significance thresholds to determine whether the operations phase of projects would result in significant impacts to regional air quality. The proposed Project would result in air pollutant emissions which are below these significance thresholds I 1 -334 (PER- 02 -0I) CITY OF SANTA ANA (11/25/2013 REV2) 132897 CM PAGE 23 55C -38