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Figure 1‑8 illustrates representations of a curved line source by multiple volume sources.  Emissions from a line source or narrow volume source represented by multiple volume sources are divided equally among the individual sources unless there is a known spatial variation in emissions.  Setting the initial lateral dimension σyo equal to W/2.15 in Figure 1‑8(a) or 2W/2.15 in Figure 1‑8(b) results in overlapping Gaussian distributions for the individual sources.  If the wind direction is normal to a straight line source that is represented by multiple volume sources, the initial crosswind concentration distribution is uniform except at the edges of the line source.  The doubling of σyo by the user in the approximate line‑source representation in Figure 1‑8(b) is offset by the fact that the emission rates for the individual volume sources are also doubled by the user.

TABLE 1‑6

SUMMARY OF SUGGESTED PROCEDURES FOR ESTIMATING

INITIAL LATERAL DIMENSIONS σyo AND

INITIAL VERTICAL DIMENSIONS σzo FOR VOLUME AND LINE SOURCES

 Type of Source Procedure for Obtaining Initial Dimension (a)  Initial Lateral Dimensions (σyo) Single Volume Source σyo =length of side divided by 4.3 Line Source Represented by Adjacent Volume Sources (see Figure 1‑8(a)) σyo =length of side divided by 2.15 Line Source Represented by Separated Volume Sources (see Figure 1‑8(b)) σyo =center to center distance divided by 2.15 (b)  Initial Vertical Dimensions (σzo) Surface-Based Source (he ~ 0) σzo =vertical dimension of source divided by 2.15 Elevated Source (he > 0) on or Adjacent to a Building σzo =building height divided by 2.15 Elevated Source (he > 0) not on or Adjacent to a Building σzo =vertical dimension of source divided by 4.3

1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - 26 - 27 - 28 - 29 - 30 - 31 - 32 - 33 - 34 - 35 - 36 - 37 - 38 - 39 - 40 - 41 - 42 - 43 - 44 - 45 - 46 - 47 - 48 - 49 - 50

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