Any township located in a county having a population of more than one hundred seventy-five thousand (175,000) and an assessed tangible valuation of not more than two hundred twenty-five million dollars ($225,000,000) and which had, prior to the effective date of this act, established a township fire department under the provisions of Kan. Stat. Ann. §§ 80-1914 to 80-1918, inclusive, is hereby authorized to levy an additional annual tax of not to exceed five (5) mills for the purpose of relocating, equipping and maintaining any existing building or facility of said fire department, or for the purpose of constructing, equipping and maintaining a new building or facility, or for both such purposes: Provided, That such tax shall not be levied, nor once levied, the levy increased until the question of levying such tax, or the increase thereof, shall have been approved by a majority of the qualified electors of such township voting thereon at a special election called for that purpose, in the manner provided for calling elections under the general bond law, or at any general election in which such proposition is submitted.