The chief executive officer of the district shall be a manager who shall be chosen by the board of directors and hold office on the same basis, possess the same qualifications, and have the same powers and duties with reference to the management of the affairs of the district, as the manager of a statutory city under sections 412.641 to 412.751, except that all appointments of subordinate officers and employees and all employment of professional consultants shall be subject to approval by the board. The district shall comply with the provisions of chapter 353 to permit membership of the manager and all employees in the Public Employees Retirement Association.