Correspondence #41 - Laserfiche WebLink

Home Browse Search

Using this equation, we estimated an operational emission rate of 0.00489 g/s. Construction and operation were simulated as a 5.13-acre rectangular area source in AERSCREEN, with approximate dimensions of 204- by 102-meters. A release height of three meters was selected to represent the height of stacks of operational equipment and other heavy-duty vehicles, and an initial vertical dimension of one and a half meters was used to simulate instantaneous plume dispersion upon release. An urban meteorological setting was selected with model -default inputs for wind speed and direction distribution. The population of Santa Ana was obtained from U.S. 2020 Census data." The AERSCREEN model generates maximum reasonable estimates of single -hour DPM concentrations from the Project Site. The U.S. EPA suggests that the annualized average concentration of an air pollutant be estimated by multiplying the single -hour concentration by 10% in screening procedures." According to the Air Quality Assessment ("AQA"), provided as Appendix A to the EA, the nearest sensitive receptor is located 700 feet, or 213 meters, from the Project site (p. 9). Thus, the single -hour concentration estimated by AERSCREEN for Project construction is approximately 1.049 µg/m3 DPM at approximately 200 meters downwind. Multiplying this single -hour concentration by 10%, we get an annualized average concentration of 0.1049 µg/m3 for Project construction at the MEIR. For Project operation, the single -hour concentration estimated by AERSCREEN is 2.849 µg/m3 DPM at approximately 200 meters downwind. Multiplying this single -hour concentration by 10%, we get an annualized average concentration of 0.2849 µg/m3 for Project operation at the MEIR. We calculated the excess cancer risk to the MEIR using applicable HRA methodologies prescribed by OEHHA, as recommended by SCAQMD.12 Specifically, guidance from OEHHA and the California Air Resources Board ("CARB") recommends the use of a standard point estimate approach, including high - point estimate (i.e. 95th percentile) breathing rates and age sensitivity factors ("ASF") in order to account for the increased sensitivity to carcinogens during early -in -life exposure and accurately assess risk for susceptible subpopulations such as children. The residential exposure parameters, such as the daily breathing rates ("BR/BW"), exposure duration ("ED"), age sensitivity factors ("ASF"), fraction of time at home ("FAH"), and exposure frequency ("EF") utilized for the various age groups in our screening -level HRA are as follows: to "Santa Anna." U.S. Census Bureau, 2020, available at. https://datacommons.org/placeZgeoldZ0669000. 11 "Screening Procedures for Estimating the Air Quality Impact of Stationary Sources Revised." U.S. EPA, October 1992, available at: http://www,epa,ov/ttn/scram/guidance/wide/EPA 454R 92 019 OCR,pdf, 12 "AB 2588 and Rule 1402 Supplemental Guidelines." SCAQMD, October 2020, available at: http://www,agmd,ov/does/default source/planning/risk assessment/ab 2588 supplemental- &uidelines.pdf?sfvrsn=19, p. 2. 4