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4.Environmental Analysis — • Suspend excavation and grading activity when winds exceed 20 mph. • Limit area subject to excavation, grading,and other construction activity to less than four acres at any one time. The following mitigation measures may be applied to construction sources of combustion: • Use of alternative fueled or catalyst equipped diesel construction equipment. — • Minimize idling time. • Limit the hours of operation of heavy duty equipment and/or the amount of equipment in use. • Replace fossil-fueled equipment with electrically driven equivalents (provided they are not run via a portable generator set). • Curtail construction during periods of high ambient pollutant concentrations;this may include ceasing of construction activity during the peak-hour of vehicular traffic on adjacent roads. • Implement activity management(rescheduling activities to reduce short-term impacts). The construction phase of the project was also analyzed for NOx emissions because it would he a large-scale project that could have significant NOx emissions.To understand the extent of the NOx emissions, an estimate was obtained for the number and type of equipment necessary to remove an average depth of 9 inches of soil from the entire 659 acres(approximately 800,000 cubic yards).6 The estimate indicated that initial site preparation,defined as"construction' for this purpose of this analysis,could be accomplished in 74 days with the following equipment: • Six Caterpillar 623G scrapers (365 horsepower); • One Caterpillar D7R dozer(240 hp); _ • One Caterpillar DSR dozer(310 hp); • One Caterpillar 140G motor grader(150 hp)- halftime; and • Two water trucks. The criteria pollutant engine emissions if all the topsoil were removed in one year are shown in Table 4.6-4. The estimates show that even if all the topsoil were removed in one year the levels of ozone precursors (ROG and NOx) would be less than significant. This table confirms that the increase in criteria pollutant emissions from engines would be less than significant even with all the topsoil grading occurring in one year. Scaling the estimated effort for the entire project back — to the effort needed for each of the nine phases of the project, topsoil removal for each phase could probably be completed in less than one month. 6 Lance A.Bushnell,Chief Estimator,Performance Excavators,San Rafael,California,February 17,2006. RMC Pacific Vernalis Quarry Mining and Reclamation Project 4.6-20 ESA/203015 Draft Environmental Impact Report May 2006