The city council of a city of the second class may, by ordinance, confer upon a board of public works the active direction and supervision of any or all of the utility systems owned or operated by such city. The city council shall approve the budget of each proprietary function as provided in the Municipal Proprietary Function Act. Such board of public works shall have the power to operate any utility referred to it and to exercise all powers conferred by law upon such city for the operation and government of such utility to the same extent, in the same manner, and under the same restrictions as the city council could do if no such board of public works existed, except that such board of public works shall not make any expenditure or contract any indebtedness other than for ordinary running expenses, exceeding an amount established by the city council, without first obtaining the approval of the city council. The board of public works shall report to the city council at regular intervals as the city council may require.