The bill amends the Natural Resources and Environmental Protection Act to enhance the Department's authority in managing environmental contamination and remedial actions. It removes previous limitations on the Department's discretion in approving response activities, allowing for a broader range of actions to protect public health and the environment. New requirements for remedial actions emphasize the need to ensure public health and safety, with specific cleanup criteria based on intended land use and groundwater standards. The bill also establishes clearer guidelines for developing cleanup criteria, allowing for site-specific criteria when categorical standards are technically infeasible, and mandates the use of the latest scientific data in determining toxicity values and cleanup criteria.

Additionally, the bill introduces provisions for the approval of remedial action plans, requiring public notice and comment on revisions to cleanup criteria. It clarifies that the Department of Environmental Quality (DEQ) can approve cleanup criteria based on biologically based models and that compliance with indoor air inhalation criteria is contingent upon occupational safety standards. The bill also modifies the process for addressing hazardous substances without generic cleanup criteria, allowing for alternative methods to demonstrate compliance. It emphasizes the importance of monitoring groundwater contamination and establishes conditions for using ecological and modeling demonstrations to show compliance with groundwater standards. Overall, the amendments aim to enhance the effectiveness, flexibility, and transparency of hazardous substance management while ensuring environmental protection and public health.