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materials (sand and gravel) over a 26- to 60 year period. The operation would be open pit, sand and gravel harvesting and processing. The impacts of operational air quality emissions of criteria pollutants are potentially significant. (Final EIR,p. 4-34.) Significance Before Mitigation: Potentially Significant Facts: Project operations would result in emission of criteria pollutants. See Final EIR,pp. 4-34 to 4-39. Mitigation Measures: Mitigation Measure 4.6.2: While several emission-reducing measures are currently available, current proven technology limits the maximum reductions. These operational impacts are a significant impact of the project after mitigation. The project proposes to operate new equipment, both on-site non road equipment and haul trucks. This provides the best available operating efficiency for the equipment. Currently, additional retrofits to reduce NOx emissions below acceptable emission standards would be cost prohibitive. Catalytic particulate filters and the use of ultra low sulfur fuels do not substantially reduce NOx emissions. (Final EIR,p. 4-39.) Findings: The impacts of operational air quality emissions of criteria pollutants would be reduced by implementation of Mitigation Measure 4.6.2, but not to a less-than-significant level. The applicant would use the latest equipment upon commencing mining, which would thereby implement BACT. ROG emissions would be just above the significance level in 2008 for annual production levels of 4 million tons. NOx emission would be 4 to 14 times above the significance criterion under the various scenarios analyzed in Tables 4.6-5A, B and C. Mitigation measures to reduce NOx impacts to less than significant are not technically feasible; thus, after mitigation this would remain a significant impact. Other technologies exist to control NOx emissions from engines, such as the use of the feel additive PuriNOx, and/or the use of urea injection system in combination with a reducing catalyst. However, these technologies have not been widely tested in the types of engines for the project. Also, they have been known to affect engine operation efficiencies and may create secondary environmental impacts. Current control technologies associated with the concrete, asphalt, and sand dryer equipment generally apply to f tgitive dust emissions and not NOx. There are no current control technologies that when applied together would reduce the total NOx emissions from the project to less than significant(that is, a 90 percent reduction). As a result, this impact is considered significant and unavoidable for the project. Based on the whole record, this Commission finds that there are no additional feasible mitigation measures that would reduce potential impacts associated with operational air quality emissions of criteria pollutants to a less than significant level. (Final FIR,p. 4-39.) 35