Item 28 - Public Hearing - ZOA No. 20204-01 South Coast Technology Center

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South Coast Technology Center Project CEQA Exemption 15183 Localized Significance Thresholds LSTs were developed in response to SCAQMD Governing Boards' Environmental Justice Enhancement Initiative (1-4). The SCAQMD provided the Final Localized Significance Threshold Methodology (dated June 2003 [revised 2008]) for guidance. The LST methodology assists lead agencies in analyzing localized air quality impacts. The SCAQMD provides the LST screening lookup tables for one-, two-, and five -acre projects emitting CO, NOx, PM2.5, or PM,o. The LST methodology and associated mass rates are not designed to evaluate localized impacts from mobile sources traveling over the roadways. The Project is located within SRA 17, Central Orange County. Construction The SCAQMD guidance on applying CaIEEMod to LSTs specifies the number of acres a particular piece of equipment would likely disturb per day.10 SCAQMD provides LST screening thresholds for one-, two, and five -acre site disturbance areas; SCAQMD does not provide LST screening thresholds for projects over five acres. The Project would actively disturb approximately three acres per day during the grading phase of construction. Therefore, the construction LST screening threshold for two acres were utilized as a conservative analysis. As discussed, the nearest sensitive receptor to the Project Site is the existing Calvary Chapel High School located approximately 100 feet to the east of the Project Site. This sensitive land use may be potentially affected by air pollutant emissions generated during on -site construction activities. LST screening thresholds are provided for distances to sensitive receptors of 25, 50, 100, 200, and 500 meters. As the nearest sensitive receptor is located approximately 100 feet (30.5 meters) from the Project Site, the lowest available LST screening values for 25 meters was used. Table 4.3-3, Localized Significance of Construction Emissions, shows the localized construction - related emissions for NOx, CO, PM,o, and PM2.5 compared to the LST screening thresholds for SRA 17. It is noted that the localized emissions presented in Table 4.3-3 are less than those in Table 4.3-2 because localized emissions include only on -site emissions (i.e., from construction equipment and fugitive dust), and do not include off -site emissions (i.e., from hauling activities). As shown in Table 4.3-3, localized construction emissions would not exceed the LST screening thresholds for SRA 17. Therefore, localized significance impacts from construction would be less than significant. Further, as discussed in the Attachment B, Health Risk Assessment, the highest expected average diesel particulate matter (DPM) emission concentrations resulting from construction of the Project at a sensitive receptor would be approximately 0.06955 pg/m3. It is acknowledged that the calculations conservatively assume no cleaner technology with lower emissions would occur in future years. Cancer risk calculations are based on 16-month maximum individual cancer risk (MICR) exposure periods. As shown in the Health Risk Assessment, the highest calculated carcinogenic risk from Project construction activities is approximately 1.71 per million for 16- month exposure at the sensitive receptor at the school and 5.68 per million for 16-month exposure at a residential sensitive receptor location east of the Project Site. Thus, the Project would not exceed the MICR of 10 in one million and impacts related to cancer risk and DPM concentrations from heavy trucks would be less than significant for the MICR. 10 The number of acres represent the total acres traversed by grading equipment. To properly grade a piece of land, multiple passes with equipment may be required. The disturbance acreage is based on the equipment list and days of the grading phase according to the anticipated maximum number of acres a given piece of equipment can pass over in an 8-hour workday. July 2024 Page 27