If additional or new assessments are so levied, such assessments shall be made on the same basis as the original assessments, and shall be levied only after all persons interested shall have been given full hearing by the board of viewers on the question of benefits and any other question on which they shall desire to be heard. Notice of such hearing shall be given by publication twice in a newspaper of general circulation published in a county in which such project is located in whole or in part, with the first publication appearing no more than 28 days before and the second publication appearing no less than seven days before the hearing. The determination of the board of viewers shall be final.