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Actual Contamination

This graphic illustrates a typical case for determining actual contamination in an air pathway. Included in this illustration are the following components:

  • Background Station. Sampling location used to determine the background level for substances in observed release evaluations.
  • Source. Represents the source of the observed release of the hazardous substance.
  • Station A. The sampling location of the air pathway from which an observed release was documented.
  • Distance Rings. Represent areas of equal distance from the source.

When an observed release has been demonstrated at Station A, all air pathway targets located in the same distance ring as Station A as well as any targets located in rings closer to the source, are considered to be subject to actual contamination. It is important to note that although the wind direction during sampling is important in determining whether an observed release has occurred, it does not otherwise affect the assessment of actual contamination.

At the Site Inspection (SI), does it make sense to put an air sampling station on the outside portion of the distance ring? ANSWER .

Actual Contamination in the Soil Exposure Pathway

Actual contamination in the soil exposure pathway is unique in several respects. It will be discussed in greater detail in Section 18: Soil Exposure Pathway - Resident Population Threat.

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