Packet_6.27.22 - Laserfiche WebLink

Home Browse Search

Cabrillo at First Mixed-Use Residential Air Quality, Global Climate Change, HRA, and Energy Impact Analysis 43 19386 DISPERSION MODELING The next step in the assessment process utilizes the emissions inventory along with a mathematical air dispersion model and representative meteorological data to calculate impacts at the various receptor locations. The dispersion model used in this assessment is described below. Model Selection The assessment of air quality and health risk impacts from pollutant emissions from the freeway applied the USEPA AERMOD Model, which is the air dispersion model accepted by the SCAQMD for performing air quality impact analyses. AERMOD predicts pollutant concentrations from point, area, volume, line, and flare sources with variable emissions in terrain from flat to complex with the inclusion of building downwash effects from buildings on pollutant dispersion. It captures the essential atmospheric physical processes and provides reasonable estimates over a wide range of meteorological conditions and modeling scenarios. AERMOD View Version 10.2.1, EPA version No. 21112, was utilized for this analysis. General Model Assumptions A summary of Emission Configurations is shown in Table 11. The basic options used in the dispersion modeling are summarized in Table 12. Meteorological Data Meteorological data (processed with the ADJ_U option) from the Air District’s John Wayne Airport monitoring site was selected for this modeling application. Five full years of sequential meteorological data was collected at the site from January 1, 2012 to December 31, 2016 by the SCAQMD. The SCAQMD processed the data for input to the model. The data was obtained from SCAQMD at: https://www.aqmd.gov/home/air- quality/air-quality-data-studies/meteorological-data/data-for-aermod (see Figure 4). ESTIMATION OF HEALTH RISKS Health risks from diesel particulate matter are twofold. First, diesel particulate matter is a carcinogen according to the State of California. Second, long-term chronic exposure to diesel particulate matter can cause health effects to the respiratory system. Each of these health risks is discussed below. Cancer Risks According to the Risk Assessment Guidelines: Guidance Manual for Preparation of Health Risk Assessments, released by the Office of Environmental Health Hazard Assessment (OEHHA) in February 2015 and formally adopted in March 2015, the residential inhalation dose for cancer risk assessment should be calculated using the following formula: [Dose-air (mg/(Kg-day)]*Cancer Potency*[1x10-6] = Potential Cancer Risk Where: Cancer Potency Factor = 1.1 Dose-inh = (C¬air * DBR * A * EF * ED *ASF*FAH* 10-6) / AT Where: Cair [Concentration in air (µg/m3)] = (Calculated by AERMOD Model) DBR [Daily breathing rate (L/kg body weight – day)] = 261 for adults, 572 for children, and 1,090 for infants, and 361 for 3rd trimester per SCAQMD Permit Application Package "N" Table 4.1 D guidance. 436/27/2022 Planning Commission 2 –96