An amendment to provide that landowners are not to be held liable if they can prove by the preponderance of the evidence that they did not conduct or permit the generation, transportation, storage, treatment, or disposal of any hazardous substance at the facility, the release or threatened release of which causes significant environmental hazard. The owner may not have acquired the property with actual or constructive knowledge that the property was used previously for generation, transportation, storage, treatment, or disposal of any hazardous substance.