(1) Unless the purpose of the special improvement district is the conversion of existing overhead utilities to an underground location, the city council has the same jurisdiction and powers as provided in 7-12-4102 and 7-12-4103 (before doing any of the work mentioned in this part) to require a public service corporation or company, firm, or person occupying the streets, avenues, or alleys, at their own expense and within a reasonable time to be fixed by the council, to place in an underground conduit, in a manner as may be directed by the council, all wires; electric conduits; or telephone, telegraph, power, or power transmission lines or appurtenances to them or appliances owned, held, or enjoyed in connection with them.
(2) The whole cost so assessed may at no time exceed the costs incurred.