(A) In order that the rates and charges may be justly and equitably adjusted to the service rendered to users, the city shall base its charges not only on the volume, but also on strength and character of the stronger-than-normal domestic sewage and wastes which it is required to treat and dispose of. The city shall require the user to determine the strength and content of all sewage and wastes discharged, either directly or indirectly into the sanitary sewage system, in a manner and by a method as the city may deem practicable in the light of the conditions and attending circumstances of the case, in order to determine the proper charge. The user shall furnish a central sampling point available to the city at all times.
(B) Normal sewage domestic waste strength should not exceed a biochemical oxygen demand of 240 milligrams per liter of fluid, a chemical oxygen demand in excess of 480 milligrams per liter of fluid, suspended solids in excess of 200 milligrams per liter of fluid, phosphorus in excess of 10 milligrams per liter of fluid or NH3 in excess of 30 milligrams per liter of fluid. Additional charges for treating stronger-than-normal domestic waste shall be made on the following basis:
(1) There shall be an additional charge of $.16 per pound for suspended solids received in excess of 200 milligrams per liter of fluid.
(2) There shall be an additional charge of $.13 per pound of biochemical oxygen demand for BOD received in excess of 240 milligrams per liter of fluid.
(3) There shall be an additional charge of $.065 per pound of chemical oxygen demand for COD received in excess of 480 milligrams per liter of fluid.
(4) There shall be an additional charge of $.50 per pound of phosphorus received in excess of 10 milligrams per liter of fluid.
(5) There shall be an additional charge of $.27 per pound of NH3 received in excess of 30 milligrams per liter of fluid.
(‘89 Code, § 103.05)