|PRELIMINARY SCREENING OF POTENTIAL FOR VAPOR CONCERNS|
|Parameter (1)||Value||Magnitude of Contamination (2)||Possible Vapor Concern? (3)|
|Vapor Pressure (mm of Hg)||<1 mm Hg||Any||No|
|1-100 mm Hg||Small||No|
|>100 mm Hg||Small||Maybe|
|Henry's Law Constant (unitless)||< 10-5||Any||No|
1. Chemical-specific values of vapor pressures and Henry's Law Constant can be found under "Chemical-Specific Information" on the toolbar.
2. The classification of magnitude of contamination is based on the area of soil or groundwater contamination relative to the size of actual or potential subsurface structures at the site and the contaminant concentration relative to its toxicity. The applicable statewide standard can be used as a gauge of toxicity of a chemical. For example, an isolated soil sample would be considered small unless the contaminant concentration was extremely high relative to the statewide standard for soil.
3. The DNR will assess situations classified as "Maybe" in greater detail before making the final determination on whether vapors need to be assessed for sites enrolled in the LRP.