ARCHIVED REPORTS LEC APPLICATION FOR CERTIFICATION

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5.1E:CONSTRUCTION EMISSIONS AND IMPACT ANALYSIS TABLE 5.1 E-3 Modeled Background Concentrations in the Project Area Pollutant Averaging Prd 2005 2006 2007 PM10 24 hour 84 85 75 annual 29.4 33.4 27.7 PM2.5a 24 hour 44 42 48 annual 12.5 13.1 12.9 a.24-hour average PM2.5 concentrations shown are 98th percentile values, based on the form of the standard. 5.1 EA2 Dispersion Model The EPA guideline AERMOD model was used to estimate ambient impacts from construction activities. The emission sources for the construction site were grouped into three categories: exhaust emissions,construction dust emissions,and windblown dust emissions. The exhaust and construction dust emissions were modeled as volume sources with a vertical dimension of 6 meters. Construction dust sources were modeled as 11 volume sources in the project site area. Combustion exhaust sources were allocated to the project site area as well as to the laydown and parking areas where construction equipment activity will also occur. The horizontal dimension of each volume source was set to 65 meters,with sigma-y= 15.116 meters (based on the width of the construction area). The windblown dust emissions were modeled as area sources. For these windblown dust sources,the area covers the active construction area. An effective plume height of 0.5 meters was used in the modeling analysis. The construction impacts modeling analysis receptor set excluded the areas under the applicant's control,including the existing NCPA property and the laydown and parking areas that will be fenced and used for equipment and worker vehicles during the construction period. To determine the construction impacts on short-term ambient standards (24 hours and less), the worst-case daily onsite construction emission levels shown in Table 5.1E-1 were used. For pollutants with annual average ambient standards,the annual onsite emission levels shown in Table 5.1E-2 were used. As with the refined modeling discussed in Section 5.1,the construction impact modeling was performed using the 2000 to 2004 Stockton monitoring station meteorological data set. 5.1 EA3 Modeling Results Based on the emission rates of NOx,SO2, CO,and PM10 and the meteorological data,the AERMOD model calculates hourly and annual ambient impacts for each pollutant. As mentioned above,the modeled 1-hour,3-hour,8-hour,and 24-hour ambient impacts are based on the worst-case daily emission rates of NOx,SO2, CO,and PM1o. The annual impacts are based on the annual emission rates of these pollutants. SAC/371322/082330017(LEC_5.1 E_APPENDIX.DOC) 5.1 E-5