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AIR QUALITY ASSUMPTIONS AND METHODOLOGY <br /> Emissions from the construction phase of the project were calculated for worst-case conditions. For <br /> PM-10, the worst case season would be summer, when soil moisture content is lowest and winds are <br /> highest. Worst case truck traffic assumptions were four round-trip truck trips per hour, 16 hours per <br /> day, 18 cubic yards of material per truck. <br /> The following predictive emission equations for PM-10 are taken from the U. S. Environmental <br /> Protection Agency's AP-42, "Compilation of Air Pollutant Emission Factors, Volume 1". <br /> Haul Road Emissions <br /> ` The predictive equation for haul trucks within the quarry area was is taken from AP-42, page 11.2.1-1: <br /> Emission (lbs/VMT) = k* 5.9*(s/12)*(S/30)*(W/3)o.'*(w/4)" <br /> where: <br /> k = particle size multiplier (0.36 for PM-10) <br /> s = silt content of graveled road surface (4.3%, taken from Table 11.2.1-1) <br /> S = average vehicle speed (taken as 25 mph) <br /> W = Vehicle Weight (taken as 35 tons) <br /> w = number of wheels per vehicle (taken as 12) <br /> The resulting emissions factor is 6.02 pounds per VMT. The proposed use of penetration oil on the <br /> graveled surface would reduce emission by about 80%, yielding an effective emission rate of 1.20 <br /> pounds per VMT. <br /> The vehicle miles travelled (VMT) on the graveled haul road is estimated at 64 based on 128 one-way <br /> trips with an average distance of 0.5 miles. The resulting emission is 76.4 pounds/day. <br /> Material Loading_ <br /> The following predictive equation for emissions from batch loading by a front end loader is found on <br /> page 11.2.3-3 of AP-42: <br />