The powers herein granted to plan, alter, enlarge, extend, improve, construct, reconstruct, develop, redevelop, operate and maintain a Sewer System or Sewer Systems and to issue bonds shall be supplemental to and not amendatory of the provisions of all other laws and shall not be construed to limit the city’s authority under the provisions of any other laws. (C.O. 84 § 6, 6-11-96.)