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should be based on a 70-year exposure period; however, such assessments should be limited to the period/duration of activities associated with the proposed project(Salinas,pers. comm., 2004). Thus,because the use of off-road heavy-duty diesel equipment would be temporary in combination with the highly dispersive properties of diesel PM(Zhu and Hinds 2002) and further reductions in exhaust emissions,project-generated, construction-related emissions of TACs would not expose sensitive receptors to substantial emissions of TACs. It is also important to note that compliance with the ISR rule,as required by law,would also reduce PM exhaust emissions. As a result, this impact would be less than significant. On-Site Operation-Related Stationary Source Emissions SJVAPCD has developed a publicly owned treatment works (POTW)worksheet,which serves as a screening tool to determine if emissions from wastewater treatment facilities could potentially represent a significant source of TACs and associated health risk(SJVAPCD 2006e). The worksheet contains emission factors for 25 TACs that are commonly associated with POTW and determines excess cancer and noncancer health risks based on such inputs as influent flow rate,methods of treatment, and digester gas and LPG combustion rates.According to SJVAPCD, if the worksheet determines that the screening value is above 10,then a more detailed analysis is required(e.g.,health risk assessment). The worksheet was populated with project specific data for the proposed Manteca WQCF at buildout conditions. Based on the analysis conducted,the screening value for the proposed project would be 6.0,which would not exceed SJVAPCD's recommended value of 10. Refer to Appendix B for detailed modeling input parameters and results. Project-generated stationary source emissions would not be a significant source of TACs. This impact would be less than significant. IMPACT Air Quality—Generation of Long-Term Operation-Related(Local)Mobile-Source Emissions of Carbon 4.3-4 Monoxide. The proposed project would generate a trip increase that is less than 1.0%of existing traffic volumes on local area roadways and would not decrease the LOS of these roadways. The proposed project would be defined as a small project(e.g.,generates less than 1,000 trips per day)for which no quantitative analysis would be required. Project-generated,long-term operation-related(local)mobile-source emissions of CO would not violate or contribute substantially to a violation of the CAAQS or NAAQS,or expose sensitive receptors to substantial pollutant concentrations. This impact would be less than significant. CO concentration is a direct function of motor vehicle activity(e.g., idling time and traffic flow conditions), particularly during peak commute hours, and meteorological conditions.Under specific meteorological conditions (e.g., stable conditions that result in poor dispersion), CO concentrations may reach unhealthy levels with respect to local sensitive land-uses such as residential areas, schools, and hospitals. As a result, SJVAPCD recommends analysis of CO emissions at a local rather than a regional level. SJVAPCD has established preliminary screening criteria to determine with fair certainty that if not violated project-generated long-term operational local mobile-source emissions of CO would not violate or contribute substantially contribute to a violation of the CAAQS or NAAQS. SJVAPCD's preliminary screening criteria include the following: ► a traffic study for the project indicates that the level of service(LOS) on one or more streets or at one or more intersections in the project vicinity would be reduced to LOS E or F; or ► a traffic study for the project indicates that implementation would substantially worsen an already existing LOS F on one or more streets or at more or more intersections in the project vicinity(SJVAPCD 2002). Furthermore,the Transportation Project-Level Carbon Monoxide Protocol(Garza et al. 1997) states that signalized intersections that operate at an LOS represent a potential for a CO violation. As described in Section 4.11 "Transportation and Circulation",the proposed project would generate 20 one-way employee passenger vehicle trips per day and less than one truck haul trip per day. These trips are less than 1.0% EDAW Manteca WQCF and Collection System Master Plans EIR Air Quality 4.3-24 City of Manteca