Whenever any city of the second class has or is about to establish or acquire any system of waterworks, power plant, ice plant, gas plant, sewerage, heating, or lighting plant, or distribution system, the city council of such city may, by ordinance, create a board of public works, which shall consist of not less than three, nor more than six members, residents of such city, to be appointed by the mayor, subject to the approval of the city council. Members of the board of public works may be removed by the mayor and a majority of the members elected to the city council at any time. The term of the first members of the board of public works shall be one, two, three, or four years in the manner designated by the mayor, as the case may be, after which the term of each member shall be four years; and the terms of not more than two members shall expire at any one time.