6 - GPA19-01; AA19-01_651 W SUNFLOWER AVENUE

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Legacy Sunflower Apartments Page 40 Mitigated Negative Declaration – March 14, 2019 SO2 1-hour average 24-hour average 0.25 ppm 0.04 ppm CO 1-hour average 8-hour average 20 ppm (23,000 µg/m^3) 9 ppm (10,000 µg/m^3) Lead 30-day average Rolling 3-month average Quarterly average 1.5 µg/m^3 0.15 µg/m^3 1.5 µg/m^3 Source: http://www.aqmd.gov/docs/default-source/ceqa/handbook/scaqmd-air-quality-significance-thresholds.pdf Local Air Quality Project-related construction air emissions may have the potential to exceed the State and Federal air quality standards in the project vicinity, even though these pollutant emissions may not be significant enough to create a regional impact to the SCAB. In order to assess local air quality impacts the SCAQMD has developed Localized Significant Thresholds (LSTs) to assess the project-related air emissions in the project vicinity. The SCAQMD has also provided Final Localized Significant Threshold Methodology (LST Methodology), June 2003, which details the methodology to analyze local air emission impacts. The Localized Significant Threshold Methodology found that the primary emissions of concern are NO2, CO, PM10, and PM2.5. Toxic Air Contaminants Construction The operation of the construction equipment that would be used to demolish, grade and construct the project would emit Diesel Particulate Matter (DPM), which is a carcinogen. However, the DPM emissions are short-term in nature. The determination of the risk from the short-term generation of DPM is considered over a 30-year exposure period because carcinogenic risk is directly related to sustain exposure. In contrast, construction activities would be limited to a period of approximately 24 months for the project based on the estimated construction schedule. Therefore, the duration of construction activities would represent a fraction of the 30-year exposure period used as the basis for assessing the significance of carcinogenic risk exposure. As a result, the project generated DPM would not represent a source of sustained DPM emissions. Therefore, due to the short construction period over the 30-year exposure period, the exposure to DPM due to the project would be less than significant. Operation The project proposes to develop the site with 226 multi-family attached residential dwelling units. Therefore, the project is not anticipated be a source of toxic air contaminants and sensitive receptors would not be exposed to toxic sources of air pollution. Short-Term Construction Impacts The construction activities necessary to develop the project would generate air emissions, toxic air contaminant emissions, etc. throughout construction. The project construction activities include the demolition of the existing church, church parking lot and other site improvements, grading the site, 6-62