With respect to a petition for the replacement of lights which includes no request for the establishment of a temporary zone, if the board of supervisors determines that it will be just and equitable and in the public interest for the additional cost, if any, of removing the obsolete lighting system and its replacement with a modern county- or utility-owned lighting system to be paid by the district as a whole, the board of supervisors shall immediately estimate the cost of replacement of the obsolete system and installation and maintenance of the modern system, and shall include in the regular tax levy for the first fiscal year in which it is possible to do so, a tax upon the taxable property within the district at the equalized value thereof, or an assessment on each parcel of real property within the district on the basis of the estimated benefit to the parcel, sufficient to pay such cost of replacement, installation and maintenance. After the tax or assessment levy has been made, the governing body shall proceed with the replacement of the obsolete system and the installation and maintenance of the modern system.