(1) For purposes of assuring protection of public health, safety, and welfare, the department shall allow the calculation of facility-specific cleanup levels using exposure assumptions and risk levels acceptable to the department.
(2) For purposes of assuring protection of the environment, the department shall allow the calculation of facility-specific cleanup levels. The department shall approve risk and leaching determinations on a facility-specific basis using science-based assumptions acceptable to the department.
(3) Except as may otherwise specifically be provided for in a settlement agreement or administrative order on consent entered into under 75-10-723, MCA, if the department selects or approves a remedial action and subsequently determines that the remedial action does not attain a degree of cleanup of the hazardous or deleterious substance and control of a threatened release or further release of that substance that assures protection of public health, safety, and welfare and of the environment, the department shall require further remedial action at the facility by a person liable or potentially liable under 75-10-715, MCA. The department shall set forth in writing the basis for requiring any further remedial action.