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(;grams 506.0lbs 453.6grams lday lhour Emission Race �secondl 795 days x Ibs x 24 hours x 3'600 seconds-0.003346 y/s' Using this equation, we estimated a construction emission rate of 0.003346 grams per second (g/s). Subtractingthe 795-day construction duration from the total residential duration of 30 years, we assumed that after Project construction, the sensitive receptor would be exposed to the Projects operational DPM for an additional 27.82 years, approximately. The Project's operational CalEEMod emissions, calculated by subtracting the existing emissions from the proposed Project, indicate that operational activities will generate approximately 530 pounds of OPM per year throughout operation. Applying the same equation used to estimate the construction OPM rate, we estimated the following emission rate for Project operation: grams _ 530.2 Abs 453.6gram.s 1 day 1 hour Emission Raee x x x - 0-007626g/s second -' 365 days It24 hou3-s 3,600 seconds Using this equation, we estimated an operational emission rate of 0.007626 g/s. Construction and operational activity was simulated as a -acre rectangular area source in AERSCREEN with dimensions of 254.4 meters by 232 meters. A release height of three meters was selected to represent the height of exhaust stacks on 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 urba in meteorological setting was selected with model -default inputs for wind speed and direction distribution. The AERSCREEN model generates maximum reasonable estimates of single -hour DPM concentrations from the Project site. EPA guidance suggests that in screening procedures, the annualized average concentration of an air pollutant be estimated by multiplying the single -hour concentration by 10%." AS previously stated, there are residential sensitive receptors located approximately 440 meters from the Project site. The single —hour concentration estimated by AERSCREEN for Project construction is approximately 0.5355 µg/m3 DPM at approximately 450 meters downwind. Multiplying this single -hour concentration by 101Y., we get an annualized average concentration 0.05355 µg/m' for Project construction at the nearest sensitive receptor. For Project operation,the single -hour concentration is estimated by AERSCREEN is approximately 1.220 µg/m' at approximately 450 meters downwind. Multiplying this single- hour concentration by 10%, we get an annualized average concentration of 0.122 µg/m' for Project operation at the nearest sensitive receptor. We calculated the excess cancer risk to the closest sensitive receptor using applicable H RA methodologies prescribed by OEHHA and the SCAQMD. Consistent with the construction schedule included in the DEIR, the annualized average concentration for construction was used for the entire third trimester of pregnancy (0.25 years) and the first 1.93 years of the infantile stage of life (0- 2 19 "Screening Procedures for Estimating the Air Quality Impact of Stationary Sources Revised"EPA, 1992, available at: hup,llwww.epa.govRm/scram/guidance/guide/CPA-454R-92-019 OCR.adf see also "Risk Assessment Ci ddelines CLJidanre Manual for Prnparatinn of HaNITh Rivk A5[e,1 nO,N' OFHHA, Fahnrary 2015, nvailnhfe of htms://oehha.m.r /media/downloadslcmr12015cuidancemanual.pdf, p. 4-36 11 36 75C-179