In some situations it may be appropriate to take action (referred to as off-site remedial actions) to minimize and mitigate the migration of hazardous substances and the effects of such migration. Theses actions may be taken when the IEPA determines that source control remedial actions may not effectively mitigate and minimize the threat and there is a significant threat to public health, welfare, or the environment. These situations typically will result from contamination that has migrated beyond the area where the hazardous substances were originally located. Off-site measures may include provision of permanent alternative water supplies, management of a drinking water aquifer plume or treatment of drinking water aquifers. The following criteria should be used in determining whether and what type of off-site remedial actions should be considered:
Ill. Admin. Code tit. 35, § 750.464