2024-053 - Final Supplemental for The Related Bristol Specific Plan Project

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significance, as shown in Draft Supplemental EIR Table 5.1-26. Therefore, LST impacts from construction of Phase 2 would be less than significant with incorporation of mitigation (Draft Supplemental EIR at pp. 5.1-33 through 5.1-34). Construction Phase 3 Table 5.1-27 of the Draft Supplemental EIR identifies daily localized onsite emissions that are estimated to occur during construction of Phase 3 of the proposed Project. As shown, emissions during the peak construction activity of site preparation during Phase 3 would exceed the SCAQMD localized significance threshold for PM2.5. However, as described previously Project Mitigation Measure AQ-1, Construction Exhaust and Dust Control, would be implemented, and would reduce PM2.5 emissions to below the SCAQMD thresholds for localized significance, as shown in Draft Supplemental EIR Table 5.1-28. Therefore, LST impacts from construction of Phase 3 would be less than significant with incorporation of mitigation (Draft Supplemental EIR at pp. 5.1-34 through 5.1- 35). Operation at Project Buildout Applying a 5-acre LST threshold as done by the Draft Supplemental EIR is a very conservative approach. As shown in Table 5.1-32 of the Draft Supplemental EIR, unmitigated emissions generated on site by the proposed Project would exceed the LST threshold for PM2.5. Therefore, operational mitigation would be required. As shown on Table 5.1-33 of the Draft Supplemental EIR, with implementation of operational mitigation measures that prohibit fireplaces, require use of electrical landscape equipment, and use of low VOC paints, PM2.5 emissions would be reduced to a less than significant level. Therefore, LST impacts of Project buildout would be less than significant with incorporation of mitigation (Draft Supplemental EIR at p. 5.1-37). Diesel Health Risk Assessment. A Health Risk Assessment (HRA) (included as Appendix C to the Draft Supplemental EIR) was prepared to evaluate the health risk impacts as a result of exposure to Diesel Particulate Matter (DPM) during construction of the proposed Project. Onsite truck idling was estimated to occur as trucks enter and travel through the site. SCAQMD recommends using a 10 in one million as the cancer risk threshold. The receptor with the greatest potential exposure to construction DPM source emissions are the closest residences, which are as close as 130 feet from construction activities. Draft Supplemental EIR Table 5.1-34 shows that DPM levels would be reduced below SCAQMD thresholds for residential and worker receptors with implementation of GPU FEI R Mitigation Measure AQ-1 and Project Mitigation Measure AQ-1 for CARE Tier 4 Final off -road construction equipment standards. Thus, construction DPM carcinogenic risks would be reduced to a less than significant level with incorporation of mitigation. The significance thresholds for DPM exposure also require an evaluation of non -cancer risk known as hazard index. A chronic hazard index of 1.0 is considered individually significant. As shown on Draft Supplemental EIR Table 5.1-35, the maximum chronic hazard index at offsite receptors during construction would be 0.003 with implementation of GPU FEIR Mitigation Measure AQ-1 and Project Mitigation Measure AQ-1 for CARB Tier 4 Final off -road construction equipment standards, which is less than the 1.0 threshold. Therefore, impacts related to non -carcinogenic hazards would be less