(2) The notice shall fix a time and place for a hearing before the district board of all objections to the plan. The hearing shall be held not less than 20 nor more than 30 days after the date of mailing, or the date of the last publication, of the notice. At the hearing the board may make changes in the plan as necessary in the light of objections or suggestions made by persons appearing at the hearing. After the hearing the board shall approve the plan as proposed, corrected or changed, by adopting an order of approval. However, if the owners of more than 50 percent of the acreage within the district, within 30 days after the date of the order approving the plan, file written objections to the order with the secretary of the district, no further action shall be taken under the order and the plan shall be considered disapproved by the district board and rejected by the landowners. When an engineering plan is rejected by the landowners, the board may obtain a new engineering plan and present it to the landowners as provided by this section. [1969 c.606 §35; 1989 c.182 §47]