1. Nothing in this section shall apply to the storage or treatment of hazardous waste by a generator on-site or to the disposal on-site of smelter slag waste from the processing of materials into reclaimed metals if the smelter was in operation prior to August 13, 1988, nor preclude the transportation of hazardous waste out of state for treatment, storage or disposal. After August 13, 1988, no person shall dispose of untreated hazardous waste in a hazardous waste disposal facility permitted in the state of Missouri.

2. Before using a hazardous waste disposal facility permitted under sections 260.350 to 260.432, generators of hazardous waste must prove that they have investigated and reviewed alternatives to landfilling to an extent acceptable to the hazardous waste management commission. The generator shall use, to the maximum extent feasible, the best demonstrated available technology for source reduction, recycling, treatment, stabilization, solidification or destruction, including, but not limited to, biodegradation, detoxification, incineration and neutralization, as determined by the commission. In determining the best demonstrated available technology, the commission shall give consideration to the relative economic feasibility of the technology, including potential future costs of cleanup and environmental damage. Such technology shall render the hazardous waste sufficiently low in toxicity, reactivity and corrosivity as to present the least possible risk to human health and safety and to the environment in the event of a release from a hazardous waste disposal facility.

3. The commission shall determine that the best demonstrated available technology is used at hazardous waste disposal facilities in the state of Missouri in accordance with the provisions of sections 260.350 to 260.432, and the federal Resource Conservation and Recovery Act (P.L. 94-580), as amended.

4. Any hazardous waste diluted below the listed concentration threshold shall remain a listed hazardous waste unless the dilution occurs as a normal part of the manufacturing process.

5. The provisions of this section shall not apply to abandoned or uncontrolled sites as listed under section 260.440, or sites listed in the national priority list pursuant to the federal Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (P.L. 96-510), as amended, unless otherwise determined by the department or required by the commission by rule.