(a) The department shall, if it determines that it is practicable and in the public interest, propose a final administrative or judicial expedited settlement with potentially responsible parties if the settlement involves only a minor portion of the response costs at a site and, if in the judgment of the department, either of the following conditions are met:

1. (1) The amount of hazardous substances and the toxic or other hazardous effects of the hazardous substances contributed by the potentially responsible party to the site are minimal in comparison to the amount and effects of other hazardous substances at the site.
2. (2) The potentially responsible party is the owner of the real property on or in which the site is located, did not conduct or permit the generation, transportation, storage, treatment, or disposal of any hazardous substance at the site, and did not contribute to the release or threat of release of a hazardous substance at the site through any act or omission. This paragraph does not apply if the potentially responsible party, at the time of the purchase of the real property, knew or should have known that the property was used for the generation, transportation, storage, treatment, or disposal of any hazardous substance.