Dispersion Modeling Clause Samples
Dispersion Modeling. The dispersion modeling was conducted following FHWA guidance on worst-case modeling as well as EPA’s 1992 Guidance for CO determinations. The modeling was conducted using CAL3QHC (version 04244)13, with the modeling inputs made consistent to the extent feasible as noted above with the approach used by the FHWA CF (which was limited to intersections). As done for emissions modeling, the dispersion modeling used conservative and, in many cases, worst-case inputs and assumptions. The modeling approach is described in greater detail below for each facility type assessed in this document.
Dispersion Modeling. Intel, in cooperation with MCESD, the United States Environmental Protection Agency ("EPA") and the Arizona Department of Environmental Quality ("ADEQ"), has performed dispersion modeling as a screening analysis for the Ocotillo Site. The screening analysis was conducted using EPA's approved SCREEN3 dispersion model (1991-1996, Trinity Consultants Inc. Version 1.0). The parameters used in the screening analysis are listed at the end of this attachment. The screening analysis assumed an emission rate of 10 tons per year for any HAP. This emission rate was based on the maximum PSELs for aggregate organic and aggregate inorganic HAPs set out in the FPA and on the assumption that any single HAP could be emitted to the full extent of the relevant PSEL. Under the screening analysis the dispersion model predicted that the emissions rate of 10 tons per year would result in maximum properly line concentrations of 14.9 micrograms per cubic meter (ug/m3) averaged over a 1 hour. period, and 5.96 ug/m3 averaged over a 24 hour period.