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5.1 AIR QUALITY <br /> TABLE 5.1-28 <br /> Highest Reported Background Concentrations in the Project Area <br /> Pollutant Averaging Period 2005 2006 2007 <br /> PMO 24 hour 84 85 75 <br /> annual 29.4 33.4 27.7 <br /> PM2.5 24 hour 44 42 48 <br /> annual 12.5 13.1 12.9 <br /> Maximum ground-level impacts due to operation of the LEC are shown together with the <br /> ambient air quality standards in Table 5.1-29. The ambient air quality modeling results are <br /> extremely conservative and are designed to overpredict ambient concentrations because they <br /> evaluate impacts under a combination of worst-case conditions that are unlikely to occur <br /> simultaneously. The modeling combines the highest allowable emission rates with the most <br /> extreme meteorological conditions and the equipment operating load conditions that result <br /> in the highest ambient impact. Therefore it is extremely unlikely that the ambient <br /> concentrations predicted by the models will ever actually be realized. However,this analysis <br /> demonstrates that even under these combinations of conditions that overpredict impacts,the <br /> LEC will not cause or contribute to violations of any state or federal air quality standards, <br /> with the exception of the state PM10 and state and federal PM2.5 standards. For this pollutant, <br /> existing concentrations already exceed the standards. However, the modeling results in <br /> Table 5.1-27 demonstrate that the project PM10 and PM2.5 impacts will be below significant <br /> impacts levels of 5 µg/m3 for the 24-hour averaging period and 1.0 µg/m3 for the annual <br /> averaging period. Therefore,the proposed project will not contribute significantly to these <br /> exceedances. <br /> TABLE 5.1.29 <br /> Modeled Maximum Impacts Plus Background <br /> Maximum Total State Federal <br /> Facility Impact Background Impact Standard Standard <br /> Pollutant Averaging Time (pg/m3) (pg/m3) (pg/m3) (pg/m3) (Ng/m3) <br /> NO2 1-hour 31.8 163.6 195.4 338 - <br /> Annual 0.3 34.0 34.3 - 100 <br /> SO2 1-hour 10.4 46.8 57.2 650 - <br /> 3-hour 7.6 28.6 36.2 - 1300 <br /> 24-hour 2.9 10.8 13.7 109 365 <br /> Annual 0.1 2.7 2.8 - 80 <br /> CO 1-hour 324 5,500 5,824 23,000 40,000 <br /> 8-hour 111 3,178 3,289 10,000 10,000 <br /> PM10 24-hour 3.7 85 88.7 50 150 <br /> Annual 0.9 33.4 34.3 20 - <br /> PM2.5 24-Hour 3.7 48 51.7 - 35 <br /> Annual 0.9 13.1 14.0 12 15 <br /> "Includes startup. Under normal operating conditions,total impact will be 27.5 pg/m3. <br /> SAC/371322/082410013(LEC_5.1_AIR_QUALITY.DOC) 5.1-41 <br />