The mayor and city council of a city of the second class may, by ordinance, authorize and empower the board of public works to cooperate and participate in a plan of insurance designed and intended for the benefit of the employees of any public utility operated by the city. For that purpose the board of public works may make contributions to pay premiums or dues under such plan, authorize deductions from salaries of employees, and take such other steps as may be necessary to effectuate such plan of insurance.