1. a) The extent to which substances pose a danger to public health, welfare, or the environment. Factors which should be considered in assessing this danger include:

   1. 1) Population at risk;
   2. 2) Amount and form of the substance present;
   3. 3) Hazardous properties of the substances;
   4. 4) Hydrogeological factors (e.g. soil permeability depth to saturated zone, hydrologic gradients, proximity to a drinking water aquifer); and
   5. 5) Climate (rainfall, etc).
2. b) The extent to which substances have migrated or are contained by either natural or man-made barriers.
3. c) The experiences and approaches used in similar situations by State and Federal agencies, other states, and private parties.
4. d) Environmental effects and welfare concerns.

Source control remedial actions may be appropriate if a substantial concentration of hazardous substances remain at or near the area where they were originally located and inadequate barriers exist to retard migration of substances into the environment. Source control remedial actions may not be appropriate if most substances have migrated from the area where originally located or if the IEPA determines that the substances are adequately contained. Source control remedial actions may include alternative to contain the eliminate potential contamination by transporting the hazardous substances to a new location. The following criteria should be assessed determining whether and what type of source control remedial actions should be considered: