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11-26-18_AGENDA PACKET
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11-26-18_AGENDA PACKET
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<br />4 <br /> <br />πΈπππ π πππ π ππ‘π α πππππ <br />π πππππαΰ΅ 377.6 πππ <br />536 πππ¦π ΰ΅ 453.6 πππππ <br />ππ ΰ΅ 1 πππ¦ <br />24 βππ’ππ ΰ΅ 1 βππ’π <br />3,600 π ππππππ ΰ΅ π.ππππππ <br />ππΰ΅ <br />Subtracting the 536βday construction duration from the total residential exposure duration of 30 years, <br />we assumed that after Project construction, the MEIR would be exposed to the Projectβs operational <br />DPM emissions for an additional 28.5 years approximately (10,414 days). The operational CalEEMod <br />modelβs annual emissions indicate that operational activities will generate approximately 161 pounds of <br />DPM per year. Applying the same equation used to estimate the construction DPM emission rate, we <br />estimated the following emission rate for Project operation. <br />πΈπππ π πππ π ππ‘π α πππππ <br />π πππππαΰ΅ 161 πππ <br />365 πππ¦π ΰ΅ 453.6 πππππ <br />ππ ΰ΅ 1 πππ¦ <br />24 βππ’ππ ΰ΅ 1 βππ’π <br />3,600 π ππππππ ΰ΅ π.ππππππ <br />ππΰ΅ <br />Construction and operational activity was simulated as a 5.95βacre rectangular area source in <br />AERSCREEN, with dimensions of 172 meters by 140 meters. A release height of three meters was <br />selected to represent the height of exhaust stacks on construction equipment and other heavyβduty <br />vehicles, and an initial vertical dimension of one and a half meters was used to simulate instantaneous <br />plume dispersion upon release. An urban meteorological setting was selected with modelβdefault inputs <br />for wind speed and direction distribution. <br />The AERSCREEN model generates maximum reasonable estimates of singleβhour DPM concentrations <br />from the Project site. EPA guidance suggests that in screening procedures, the annualized average <br />concentration of an air pollutant be estimated by multiplying the singleβhour concentration by 10%.8 <br />There are residences located approximately 25 meters away from the Project boundary. The singleβhour <br />concentration estimated by AERSCREEN for Project construction is approximately 4.047 µg/m3 DPM at <br />approximately 25 meters downwind. Multiplying this singleβhour concentration by 10%, we get an <br />annualized average concentration of 0.4047 µg/m3 for construction. For Project operation, the singleβ <br />hour concentration in AERSCREEN is approximately 2.534 µg/m3 DPM at approximately 25 meters <br />downwind. Again, multiplying this singleβhour concentration by 10%, we get an annualized average <br />concentration of 0.2534 µg/m3 for operation. <br />We calculated the excess cancer risk to the residential receptors located closest to the Project site using <br />applicable HRA methodologies prescribed by OEHHA and the South Coast Air Quality Management <br />District (SCAQMD). Consistent with the construction schedule proposed by the DEIR, the annualized <br />average concentration for construction was used for the entire 3rd trimester of pregnancy (0.25 years), <br />and the first 1.22 years of the infantile stage of life (0β2 years). The annualized average concentration for <br />operation was used for the remainder of the 30βyear exposure period, which makes up the remainder of <br />the infantile stage of life, the entirety of the child stage of life (2 to 16 years), and the entirety of the <br />adult stage of life (16 to 30 years). Consistent with OEHHA guidance, we used Age Sensitivity Factors <br />(ASFs) to account for the heightened susceptibility of young children to the carcinogenic toxicity of air <br /> <br />8 http://www.epa.gov/ttn/scram/guidance/guide/EPAβ454Rβ92β019_OCR.pdf
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