Item 09 - Fairview Street Improvement Project

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Analysis Supporting Categorical Exemption 4.3.1.2 South Coast Air Quality Management District Localized Significance Thresholds In addition to regional significance thresholds, the SCAQMD developed localized significance thresholds (LSTs) for emissions of NO2, CO, PM10, and PM2.5 generated at new development sites (offsite mobile source emissions are not included in the LST analysis protocol). LSTs represent the maximum emissions that can be generated at a Project Site without expecting to cause or substantially contribute to an exceedance of the most stringent national or state ambient air quality standards. LSTs are based on the ambient concentrations of that pollutant within the Project source receptor area (SRA), as demarcated by the SCAQMD, and the distance to the nearest sensitive receptor. The Project Site is located within SCAQMD SRA 17(Central Orange County).Table 2 shows the LSTs for a one-, two-, and five-acre Project Site in SRA 17 with sensitive receptors located within 25 meters of the Project Site. Table 2. Local Significance Thresholds at 25 Meters of a Sensitive Receptor Pollutant (pounds per day) Project Size Construction/ Operations NOx CO PM10 PM2.5 1Acre 81 /81 512/512 4/1 3/1 2Acres 115/115 754/754 6/2 411 5 Acres 183/183 1,323 /1,323 13/3 7/2 4.3.2 Data Points 4.3.2.1 Project Construction-Generated Criteria Air Quality Emissions Regional Construction Significance Analysis Construction-generated emissions are temporary and short-term but have the potential to represent a significant air quality impact. The basic sources of short-term emissions that will be generated through construction of the Proposed Projectwould be from ground-disturbing activities and from the operation of the construction vehicles(i.e., trenchers, dump trucks). Construction activities such as excavation and grading operations, construction vehicle traffic, and wind blowing over exposed soils would generate exhaust emissions and fugitive PM emissions that affect local air quality at various times during construction. Effects would be variable depending on the weather, soil conditions, the amount of activity taking place, and the nature of dust control efforts. The dry climate of the area during the summer months creates a high potential for dust generation.Construction activities would be subject to SCAQMD Rule 403,which requires taking reasonable precautions to prevent the emissions of fugitive dust, such as using water or chemicals, where possible, for control of dust during the clearing of land and other construction activities. ECORP Consulting, Inc. 8 January 2025 Fairview Street Widening Project 2024-088.03 9-20