The town may enter upon or do construction in, on, or over any county public way for the purpose of installing or repairing any equipment or doing any other things necessary to establish, operate and maintain the water system, water plant, sanitary sewerage system, sewage treatment plant, or storm water sewers provided for in this charter. Unless required by the county, the town need not obtain any permit or pay any charge for these operations, but it must notify the county of its intent to enter on the public way and must leave the public way in a condition not inferior to that existing before.