(a) After its investigation and hearing thereon, the Arkansas Public Service Commission may modify or disapprove all or any portion of the surcharge upon a finding that:
(1) The investments or expenses were not reasonably incurred to comply with legislative or administrative rules or requirements;
(2) The investments or expenses do not relate to the protection of the public health, safety, or the environment;
(3) The investments or expenses were not substantiated;
(4) The amount of the surcharge has been erroneously calculated;
(5) The investments or expenses are already being recovered in existing rates;
(6) The investments or expenses were reasonably known and measurable at a time that allowed for a reasonable opportunity for their inclusion and consideration for recovery in the public utility's last general rate case;
(7) The investments or expenses were not reasonably incurred;
(8) The investments or expenses can otherwise be recovered in a prompt and timely manner;
(9) The allocation of the surcharge among the customers of the public utility is unreasonable; or
(10) The investments or expenses were not:
(A) Mandatory;
(B) A condition of continued operation of a utility facility; or
(C) Previously approved by the commission.
(b)
(1) If the commission determines that the allocation of the surcharge among the customers of the utility should be modified, it shall fix and determine the appropriate allocation among the utility's customers which shall be applied prospectively.
(2) The commission shall further direct the utility to credit or charge, as the case may be, the affected classes of customers whose surcharges were determined to be improperly allocated for the period between the effective date of the surcharge and the effective date of the modification. As to those classes of customers entitled to credits, the utility also shall pay interest on those credits, as applicable.
(c) If the commission determines that all or any portion of the proposed surcharge should be disapproved under subsection (a) of this section, the commission shall determine the just and reasonable amount of the surcharge to be charged or applied by the public utility after the time the proposed surcharge took effect. In the same order, the commission shall fix the amounts, plus interest, if any, to be refunded to the utility's customers.