(a) General rule.--Notwithstanding any other provision of law, the provisions of this section shall provide the exclusive method of challenging either the administrative record developed under section 506¹ or a decision of the department based upon the administrative record.

(b) Timing of review.--Neither the board nor a court shall have jurisdiction to review a response action taken by the department or ordered by the department under section 505² until the department files an action to enforce the order or to collect a penalty for violation of such order or to recover its response costs or in an action for contribution under section 705.³ In the case of an action to enforce an order of the department, the person receiving such order shall be entitled to challenge said order within 30 days from the date the department moves to enforce its order.

(c) Grounds.--A challenge to the selection and adequacy of a remedial action shall be limited to the administrative record developed under section 506. In a challenge to liability for natural resource damages, civil penalties or the recovery of response costs, or where the assessment of civil penalties is challenged, the record shall be limited to the administrative record developed under section 506, except that it may be supplemented with additional evidence supporting or refuting the department's determination that a person is a responsible person under section 701⁴ or the department's assessment of civil penalties. The party challenging the department's determination or assessment shall retain the burden of proving the department's determination or assessment was arbitrary and capricious.

(d) Procedural errors.--Procedural errors in the development of the administrative record shall not be a basis for challenging a response action unless the errors were so serious and related to matters of such central relevance to the response action that the action would have been significantly changed had the errors not been made. The person asserting the significance of the procedural errors shall have the burden of proving that the action would have been significantly changed.

(e) Remand.--When a response action is demonstrated to be arbitrary and capricious on the basis of the administrative record developed under section 506, or when a procedural error occurred in the development of the administrative record which (error) would have significantly changed the response action, the following apply: