If upon the completion of any such project it is determined that the amount assessed will not be sufficient to pay that portion of the cost which the Council has determined shall be assessed against private property, the Council may make an additional assessment of such deficiency upon the property in the assessment district in the same ratio as the original assessment. If the amount assessed in the original assessment is 5% or more greater than the cost of the project, the Council shall, by resolution, order such excess refunded proportionately to the then owners of the properties in the assessment district, provided, however, that there shall be no refund in any amount of $10 or less. If any assessment is declared void or invalid by the Council or by a court of competent jurisdiction, a reassessment may be made.
(O.C. § 1.44)