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Table 4.5-9 Predicted Carbon Monoxide Concentrations' (Alternatives 1, 2, and 3) Ambient Existing Cumulative Averaging Air Quality Existing Plus Plus E� Intersection Time Standards Conditions' Project° Project° SR 132 and 1-hour 20 10.3 10.3 10.6 Koster Road 8-hour 9 4.7 4.7 4.9 ' Concentrations are listed in parts per million(ppm). Concentrations are the sum of the maximum ambient 1-and 8-hour concentrations of 10ppm and 4.5ppm respectively (measured at the Stockton-Hazelton monitoring Station in 1995)and locally generated CO(as determined by CALINE4 based on worst-case wind angles. A persistence factor of 0.7 was used to convert modeled 1-hour concentrations to 8-hour concentrations 2 State and Federal 8-hour standard, State 1-hour standard. 3 Based on a.m. peak-hour traffic estimates. a Based on existing a.m. peak-hour traffic data plus anticipated project contribution. Source: EDAW 1997 Alternative 4: No Project This alternative would not result in local emissions of CO. No new construction or operational emissions would be generated, therefore, no adverse impact related to local mobile source emissions would result from this alternative. No mitigation is required. Impact 4.5-4 Toxic Air Contaminants Toxic air contaminants are air pollutants which may cause adverse health effects. The impacts are often localized near the source of emissions. Conventional ambient air quality standards have not yet been established by the state or federal governments for toxic air contaminants. However, as part of the permitting and new source review process, the SJVUAPCD conducts a risk assessment for the purpose of identifying nearby sensitive receptors and related risks. Should any significant risks be identified, the project will be subject to mitigation measures incorporated into the permitting requirements which will be imposed for the operation of the facility (Gormley, 1997). All uar Excavation Alternatives 1 2 and 3 Based on conversations with the SJVUAPCD, the potential hazardous impacts associated with the use of hazardous materials and the proximity to sensitive receptors would be essentially the same for Alternatives 1, 2, and 3. Equipment types, operational rates, and plant operations would be essentially the same for all three of these alternatives (Gormley 1997). Draft Environmental Impact Report 4-80 ER-96-3