06 16 20 PWA_02_02 Exh2 - IS-MND

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L w`J' FAIRVIEw BRIDGE REPLACEMENT AND STREET IMPROVEMENTS (9TH STREET TO 16TH STREET) PROJECT $ANTA ANAL CALIFORNIA INITIAL STUDY/MITIGATED NEGATIVE DECLARATION MAY 2020 In developing thresholds of significance for air pollutants, the SCAQMD considered the emission levels for which a project's individual emissions would be cumulatively considerable. If a project exceeds the identified significance thresholds, its emissions would be cumulatively considerable, resulting in significant adverse air quality impacts to the region's existing air quality conditions. Therefore, additional analysis to assess cumulative impacts is unnecessary. The following analysis assesses the potential project -level air quality impacts associated with construction and operation of the proposed Project. The SCAQMD used the NAAQS/CAAQS emission concentrations as a guide to establish the CEQA project -level thresholds for reactive organic gases (ROG), oxides of nitrogen (NOx), CO, sulfur dioxide (S02), PM1o, and PM2.5. The SCAQMD has established thresholds of significance for criteria pollutant emissions generated during both construction and operation of projects as shown in Table 3.3.A below. Table 3.3.A: SCAQMD Construction and Operation Thresholds of Significance (Ibs/day) ROG NOx co 502 PM10 PM2.5 Construction Thresholds 75 100 550 150 150 55 Operation Thresholds 55 55 550 150 150 55 Source: SCAQMD (1993). CO = carbon monoxide Ibs/day = pounds per day NOx = oxides of nitrogen PM2.5 = particulate matter less than 2.5 microns in diameter PM,o = particulate matter less than 10 microns in diameter ROG = reactive organic gases SCAQMD = South Coast Air Quality Management District S02 = sulfur dioxide The following sections describe the proposed Project's construction- and operation -related air quality impacts. Construction Emissions. During construction, short-term degradation of air quality may occur due to the release of particulate emissions generated by excavation, grading, hauling, and other activities related to construction. Emissions from construction equipment also are anticipated and would include CO, NOx, ROG, directly emitted particulate matter (PM2.5 and PM1o), and toxic air contaminants (TACs; e.g., diesel exhaust particulate matter). Site preparation and roadway construction would involve clearing, cut -and -fill activities, grading, and paving roadway surfaces. Construction -related effects on air quality from most roadway projects would be greatest during the site preparation phase because most engine emissions are associated with the excavation, handling, and transport of soils to and from the site. If not properly controlled, these activities would temporarily generate CO, NOx, ROG, PM1o, and PM2.5. Sources of fugitive dust would include disturbed soils at the construction site and trucks carrying uncovered loads of soils. Unless properly controlled, vehicles leaving the site would deposit mud on local streets, which could be an additional source of airborne dust after drying. PM10 emissions would vary from day to day, depending on the nature and magnitude of construction activity and local weather conditions. PM10 emissions would also depend on soil moisture, the silt content of soil, wind speed, and the amount of equipment operating at the time. Larger dust 3-8 R:\WKE1702\ISMND\Final ISMND\Fairview Street Bridge Final ISMND.docx (05/26/20)