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City of Santa Ana Addendum to the <br />MainPlace Mall Transformation Proiect Fashion Square Commercial Center Final EIR <br />Although the Project site is larger than 5 acres, the applicable SCAQMD localized <br />thresholds for a 5-acre site from the "Final Localized Significance Threshold <br />Methodology" document's mass rate look -up tables are used to provide a conservative <br />screening analysis. This is conservative because it estimates emissions from the larger <br />area and concentrates them into a 5-acre site. If the emissions from the larger area are <br />less than the thresholds for a 5-acre area, it can be assured that impacts would be less <br />than significant. <br />The closest sensitive receptor is 300 feet from the Project site; therefore, the LST <br />values for 100 meters (328 feet) were used. As identified in Table AQ-3, the operational <br />area source emissions would be below the LSTs. Therefore, operational LST impacts <br />would be less than significant. No new impact would occur. <br />Table AQ-3: Localized Significance of Operational Emissions <br />Activity <br />NO: <br />CO <br />PM2.e <br />PM10 <br />Area Source Emissions <br />2 <br />158 <br />1 <br />1 <br />LST Screening Threshold <br />(conservatively 5 acres at 100 meters) <br />226 <br />2,112 <br />15 <br />49 <br />Exceed SCAQMD Threshold? <br />No <br />No <br />No <br />No <br />Source: Air Quality Assessment, 2019 <br />Toxic Air Contaminants <br />In urban communities, vehicle emissions contribute significantly to localized <br />concentrations of air contaminants and CARB has issued advisory recommendations for <br />siting new sensitive land uses in proximity to sources associated with TAC's and <br />recommends performing site specific environmental evaluations. Because the Project <br />site is located within an urban community approximately 150 feet northeast and 150 feet <br />south of 1-5 and SR-22, respectively, which have substantial daily vehicle and truck <br />volumes, the contaminants generated from the roadway were identified by an HRA <br />prepared for the proposed Project to provide risk estimates related to air contaminants <br />that are reflective of anticipated exposures experienced at the site. Emissions from <br />vehicle traffic along both freeways were calculated using information derived from traffic <br />count, vehicle fleet profile, vehicle speed data collected by the California Department of <br />Transportation (Caltrans) Annual Average Daily Traffic (AADT) census. <br />The Health Risk Assessment (HRA) determines that with incorporation of MERV 13 (or <br />equivalent) ventilation systems, as proposed, the highest hourly average diesel PM10 <br />emission concentration at the site resulting from truck traffic on the freeways would be <br />0.11 pg/m3. The highest expected annual average diesel PM10 emission concentrations <br />at the site would be 0.049 pg/m3 (HRA 2019). The HRA conservatively assumes no <br />cleaner technology with lower emissions in future years. As shown in Table AQ-4, the <br />highest calculated carcinogenic risk at the Project site would be on the first floor and the <br />117 <br />