2011-022 - Addendum to the FInal Environmental Impact Report No. 2004-02

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MacArthur Project Modification — Santa Ana - Air Quality Assessment KPC Environmental, Inc. 4.3 Determining Emission Significance 4.3.1 Emission Significance Thresholds To identify projects that will adversely affect the regional air quality through direct and indirect sources the SCAQMD has established significance thresholds to determine air quality impacts of a project. The SCAQMD established these significance thresholds, in part, based on Section 182 (e) of the Federal Clean Air Act, which identified levels of volatile organic gases from stationary sources operating in extreme non - attainment regions for ozone at 10 tons per year. The value set by the CAA was converted into threshold levels in pounds per day for the construction and operational phases of a project. The SCAQMD states that any project located in the South Coast Air Basin (SCAB) having daily emissions from both direct and indirect sources that exceed the emissions thresholds should be considered significant. To determine whether or not air quality impacts from the proposed project are significant, impacts will be evaluated and compared to the significance criteria in the following table. If impacts equal or exceed any of the following criteria, they will be considered significant. Table 4 -4 Mass Daily Thresholds Pollutant Construction Operation NOx 100 lbslday 5 5 lbslday ROGNOC 75 lbslday 55 lbslday PM 10 150 lbslday 150 lbslday Sox 150 lbslday 150 lbslday CO 550 lbslday 550 lbslday PM2.5 55 lbs/day 5 5 lbslday In addition to the significance threshold for N4x, ROGNOC, PM i D, Sox and CO, the California State 1-hour and 8 -hour CO standard is used for determining the existence of CO Hotspots created directly or indirectly by a project. The criteria for CO Hotspots are covered in the CO Hotspot Analysis of this report. 02/02/11 9