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Dispersivity results

Dispersivity Estimates
Source Value
Report 18.7 feet
"One Tenth" 19.2 feet
OnSite dispersivity calculator 10.8 feet

Limitations of Dispersivity Estimates

The dispersivity values are mainly limited by the fact that none of these estimates are site-specific. In 1992 a data tabulation was published that related problem (plume) scale to dispersivity. The various "rules-of-thumb" are either based on this data set or can be related to it.

Dispersivity Data (Gelhar et al.)
Gelhar et al., 1992 Dispersivity Data Tabulation

Begins to raise a red flag icon The main point in showing this data here, is to show that for any given scale there were 2 or 3 orders of magnitude variation in dispersivities. The authors' conclusion was that the lower part of the data range was the most reliable, but that caution should be exercised in using the tabulated data for a specific site.
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