If, by the effective date of the proposed change in rates and charges, the Arkansas Public Service Commission has received petitions from fewer than fifteen percent (15%) of the member-consumers requesting that the commission apply rate case procedures, then the commission shall immediately certify that fact to the co-op. The proposed rates and charges shall become effective as published in the notice to the member-consumers. Rates and charges so established shall be in effect for not less than one (1) year, subject to the procedure provided for in § 23-4-906. If, on or before the effective date of the proposed change in rates and charges, the commission has received petitions from ten percent (10%) of the member-consumers, then the commission shall notify the co-op that it will apply rate case procedures.