2014-069 - Final Environmental Impact Report No. 2014-01

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HARBOR BLVD. MIXED USE TRANSIT CORRIDOR PLAN FINAL FIR CITY OF SANTA ANA 5. Environmental Analysis 5.2 AIR QUALITY This section of the Environmental Impact Report (EIR) evaluates the potential for the Harbor Boulevard Mixed Use Transit Corridor Plan (proposed project) to impact air quality in a local and regional context. The analysis in this section is based on buildout of the proposed land use plan, as modeled using the California Emissions Estimator Model (CalEEMod), and trip generation provided by IBI Group, as modeled using the Orange County Transportation Analysis Model (OCTAM) (see Appendix G to this EIR). The air quality model output sheets are included in Appendix C of this EIR. 5.2.1 Environmental Setting South Coast Air Basin The project site lies within the South Coast Air Basin (SoCAB), which includes all of Orange County and the nondesert portions of Los Angeles, Riverside, and San Bernardino counties. The SoCAB is in a coastal plain with connecting broad valleys and low hills and is bounded by the Pacific Ocean in the southwest quadrant, with high mountains forming the remainder of the perimeter. The general region lies in the semipermanent high- pressure zone of the eastern Pacific. As a result, the climate is mild, tempered by cool sea breezes. This usually mild weather pattern is interrupted infrequently by periods of extremely hot weather, winter storms, and Santa Ana winds (SCAQMD 2005). Temperature and Precipitation The annual average temperature varies little throughout the SoCAB, ranging from the low to middle 60s, measured in degrees Fahrenheit ( °F). With a more pronounced oceanic influence, coastal areas show less variability in annual minimum and maximum temperatures than inland areas. The climatological station nearest to the project site is the Santa Ana Fire Station Monitoring Station (ID No. 047888). The average low is reported at 43.1 °F in January, and the average high is 84.7 °F in August (WRCC 2013). In contrast to a very steady pattern of temperature, rainfall is seasonally and annually highly variable. Almost all rain falls from November through April. Summer rainfall is normally restricted to widely scattered thundershowers near the coast, with slightly heavier shower activity in the east and over the mountains. Rainfall averages 13.69 inches per year in the project area (WRCC 2013). Humidity Although the SoCAB has a semiarid climate, the air near the earth's surface is typically moist because of the presence of a shallow marine layer. Except for infrequent periods when dry, continental air is brought into the SoCAB by offshore winds, the "ocean effect" is dominant. Periods of heavy fog, especially along the coast, are frequent. Low clouds, often referred to as high fog, are a characteristic climatic feature. Annual average humidity is 70 percent at the coast and 57 percent in the eastern portions of the SoCAB (SCAQMD 2005). October 2014 Page 5.2 -1