The strength of wastewaters shall be determined, for periodic establishment of charges provided for in §§ 51.25 through 51.38, from samplings taken at the aforementioned structure at any period of time and of a duration and in a manner as the city may elect, or at any place mutually agreed upon between the user and the city. Appropriate charges for sampling and analysis shall be assessed to the user by the city. The results of routine sampling and analysis by the user may also be used for determination of charges after verification by the city.
(‘89 Code, § 100.10)