Synopsis As Introduced Amends the Illinois Municipal Code. Defines "underground" and "undergrounding". Provides that public utilities shall underground 138 kilowatt or greater electric transmission lines under certain conditions. Provides that the Illinois Commerce Commission shall allow a public utility to recover from all retail customers in its service territory all reasonable and prudent costs that it incurs related to the undergrounding of a 138 kilowatt or greater electric transmission line. Provides that a public utility shall record and defer costs that it incurs related to the undergrounding of transmission lines as a regulatory asset to be included in the public utility's total rate base and amortized over a reasonable period that is equal to the expected life of such transmission line. Effective immediately.