After the establishment of a district, applicants desiring to develop real property in the district shall, in addition to any other fees imposed by city ordinance, regulation or state law, pay a charge based on acreage, and, where appropriate, on frontage which shall be established as to amount by establishing the total estimated installation cost of the public improvements to be constructed, including the costs of formation of the district, at the estimated time of construction, and by apportioning the estimated total cost according to the benefits received, based upon total acreage and, where appropriate, frontage benefit. The apportionment formula and amount of charges shall be established by the city council in the resolution creating the district after considering the recommendations of the city engineer and the director of planning as to fair apportionment of the benefits received by each area within the district, and of the public hearing on the matter. The determination of the benefit formula, as finally established by the city council, shall be final. Alternately, in the event of improvement constructed at city or Petaluma community development commission’s expense, the charge shall be the actual cost of improvements plus a fifteen percent engineering fee. (Ord. 1977 NCS §5, 1995; Ord. 1303 NCS §l (part), 1978.)