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To identify projects that will adversely affect the regional air quality through direct and indirect sources, the <br />SCAQMD has established significance thresholds to determine air quality impacts from a project. The Air <br />Quality Assessment evaluated and compared the project emissions to the significance criteria in the <br />following table. <br />Mass Daily Thresholds <br />Pollutant <br />Construction <br />operation <br />NOx <br />100 Ibslday <br />55 Ibslday <br />ROGIVoC <br />75 Ibslday <br />55 Ibslday <br />PM10 <br />150 Ibslday <br />150 Ibslday <br />sox <br />150 Ibslday <br />150 Ibslday <br />Co <br />550 lbslday <br />550 Ibslday <br />PM2.5 <br />55 Ibslday <br />55 Ibslday <br />The SCAQMD has requested that all projects less than five acres in size complete a Localized Significance <br />Threshold (LST) Analysis to review potential impacts on sensitive receptors. The following table depicts the <br />projected project impacts compared to the significance thresholds established by the SCAQMD. As shown, <br />the project is not anticipated to exceed established thresholds. <br />LST Results <br />Construction Phase <br />Co <br />NOx <br />PM10 <br />PM2.5 <br />No Demolition <br />0.0 <br />0.0 <br />0.0 <br />0.0 <br />No Site Preparation <br />0.0 <br />0.0 <br />0.0 <br />0.0 <br />Grading <br />16.9 <br />37.1 <br />2.2 <br />1.8 <br />Building <br />12.5 <br />31.0 <br />1.7 <br />1.5 <br />Localized Significance -rhreshold <br />753.0 <br />83.0 <br />12.0 <br />4 <br />Exceed Significance? <br />No <br />No <br />No <br />No <br />The emissions estimates for the project present the "worst- case" scenario with limited mitigation included in <br />the modeling and PM10 (fugitive dust) from grading activities calculated at the worst -case level of 20 lbslday <br />rather than the average 10 lbslday in order to determine the highest potential levels of emissions. The <br />construction schedule is based on 250 working days for all construction related activities <br />(excavation/grading, trenching, construction and architectural coating). The calculations assume that the <br />majority of equipment is operating 5 days per week for 5 to 8 hours per day. It is unlikely that the majority of <br />the equipment on -site will be operated at this schedule and producing the emissions calculated. Modeling is <br />based on the square footage calculations included on the site plan. <br />Construction Emissions <br />On -site construction emissions generally consist of exhaust emissions (CO, ROGVOC, NOx, SOx, PM10, <br />CO2 and PM2.5) from construction equipment, grading, excavation, asphalt paving and painting. Off -site <br />emissions typically consist of exhaust emissions from truck traffic and worker commute trips, road dust and <br />fugitive dust from trucks hauling materials from the site. Each phase of construction is modeled individually <br />and the results are presented below. <br />Mass GradinglParking Structure Excavation Emissions <br />The default scenario used to model this phase included use of 5 pieces of heavy equipment including <br />2 excavators, l grader, 1 rubber -tired dozer, 1 tractorlloaderlbackhoe and 1 other piece of equipment over a <br />period of approximately 40 active work days. Emissions include the export of approximately 200,000 cy of <br />MacArthur Place South EIR — 2011 Addendum 21 <br />