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further into hourly process rates in pounds per hour. These calculations contain an <br /> error that results in a considerable underestimate of fugitive dust PM10 Emissions. <br /> Emission factors used by ESA to calculate hourly, daily, and annual PM10 <br /> emissions are given in pounds per ton, and thus emissions are calculated from <br /> process rates based on tons per year, rather than cubic yards per year. To convert the <br /> annual process rates from cubic yards per year to tons per year, one must know the <br /> unit weight of concrete in tons per cubic yard. Usually, a unit weight of 150 pounds <br /> per cubic foot(equivalent to 2.025 tons per cubic yard34) is assumed for normal- — <br /> weight concrete. The conversion factor used in the ESA spreadsheets, 1.504 tons per B-38 <br /> cubic yard (equivalent to 111 pounds per cubic footn would be appropriate for cont. <br /> structural light-weight concrete. (Nunnally 200136, attached as Exhibit 2.) The Draft <br /> EIR contains no discussion that the Project would only produce structural light- <br /> weight concrete. It can be assumed that the Project would produce regular average- <br /> weight concrete, which is 35 percent37 heavier. <br /> Because the emission estimates are based on the process rate in tons per year, — <br /> rather than cubic yards per year, the emission estimates in the Draft EER are <br /> underestimated by 35 percent. Inset Table 3 compares the annual process rate and <br /> resulting PM10 emission estimates based on the unit weight of light-weight and _ <br /> normal-weight concrete, respectively. <br /> 34(150 lb/ft3) x (27 W/yd3)/ (2,000 lb/ton)=2.025 ton/yd3. <br /> 35(1.504 ton/yd3)/ (27 ft3/yd3) x (2,000lb/ton)=111.41b/W. — <br /> 36 S.W.Nunnally,Construction Methods and Management,5th Ed.,2001,Prentice Hall,Upper Saddle <br /> River,NJ,pp.162-163. <br /> 37 2.025/ 1.504=1.35. <br /> 28 <br />