ARCHIVED REPORTS LEC APPLICATION FOR CERTIFICATION

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APPENDIX 5.1G Cumulative Impacts Analysis for the LEC Cumulative air quality impacts from the LEC and other reasonably foreseeable projects will be both regional and localized in nature. Regional air quality impacts are possible for pollutants such as ozone,which is formed through a photochemical process that can take hours to occur. Carbon monoxide,NOx,and SOx impacts are generally localized in the area in which they are emitted. PM10 can create a local air quality problem in the vicinity of its emission source,but can also be a regional issue when it is formed in the atmosphere from VOC,SOx, and NOx. The cumulative impacts analysis considers the potential for both regional and localized impacts due to emissions from proposed operation of LEC. Regional impacts are evaluated by comparing maximum daily and annual emissions from LEC with emissions of ozone and PM10 precursors in both San Joaquin County and the entire San Joaquin Valley. Localized impacts are evaluated by looking at other local sources of pollutants that are not included in the background air quality data to determine whether these sources in combination with LEC would be expected to cause significant cumulative air quality impacts. Regional Impacts Regional impacts are evaluated by assessing LEC's contribution to regional emissions. Although the relative importance of VOC and NOx emissions in ozone formation differs from region to region and from day to day,state law requires reductions in emissions of both precursors to reduce overall ozone levels. The change in the sum of emissions of these pollutants,equally weighted,provides a rough estimate of the impact of LEC on regional ozone levels.12 Similarly, a comparison of the emissions of PM10 precursor emissions from LEC with regional PM10 precursor emissions provides an estimate of the impact of LEC on regional PM10 levels. Under SJVAPCD regulations,LEC will be required to provide offsets for increases in NOx,VOC,SO2,and PM10 emissions from the project above certain regulatory thresholds. Regulatory offset requirements are calculated based on quarterly emissions,but the regional inventories are expressed in tons per day of emissions. Comparisons are shown on both a daily and annual basis. Tables 5.1G-1 and 5.1G-2 summarize these comparisons. LEC emissions are compared with regional emissions in 2012,as that is the year the project is expected to begin operation.San Joaquin County and SJVAPCD emissions projections for 2012 were estimated by averaging the projected emissions inventories for 2010 and 2015 obtained from the Air Resources Board's web-based emission inventory projection software, available at www.arb.ca.gov/applemsinvlemssumcat2007.php. 12 LEC is proposing to use direct, and not interpollutant,offsets for ozone precursors,so all NOx emissions from the project will be offset using NOx ERCs while all VOC emissions will be offset using VOC ERCs.