No person shall discharge or cause to be discharged the following described substances, materials, water or wastes if it appears likely in the opinion of the city that the wastes can harm either the sewers, sewage treatment process or equipment, cause the treatment facility to violate its NPDES permit on the receiving water quality standards or can otherwise endanger life, limb, public property or constitute a nuisance. In forming an opinion as to the acceptability of these wastes, the city will give consideration to such factors as the quantities of subject wastes in relation to flows and velocities in the sewers, materials of construction of the sewers, nature of the sewage treatment process, capacity of the sewage treatment plant, degree of treatability of wastes in the sewage treatment plant and other pertinent factors. The substances prohibited are:
   (A)   Any liquid or vapor having a temperature higher than 150°F (65°C);
   (B)   Any water or waste containing fats, wax, grease or oils, whether emulsified or not, in excess of 100 mg/l or containing substances which may solidify or become viscous at temperatures between 32° and 150°F (0° and 65°C);
   (C)   Any garbage that has not been properly shredded; the installation and operation of any garbage grinders equipped with a motor of one-half horsepower or greater shall be subject to review and approval of the City Engineer;
   (D)   Sewage with a concentration of pollutants in excess of the following limits is prohibited:
Concentration in Milligrams per Liter
Arsenic as As
Barium as Ba
Boron as B
Cyanides as CN (amenable)
Fluoride as F
Chromium (Total) as Cr
Magnesium as Mg
Manganese as Mn
Copper as Cu
Zinc as Zn
Cadmium as Cd
Lead as Pb
Tin as Sn
Silver as Ag
Mercury as Hg
Nickel as Ni
Iron as Fe
Note: Any water or wastes containing an aggregate of more than 15 mg/l of the above heavy metals shall be discharged to the sewer at a pH between 8.0 and 9.5. All metals are to be measured as total metals.
   (E)   Any waters or wastes exerting an excessive chlorine requirement, to such a degree that any such material received in the composite sewage at the sewage treatment plant exceeds the limits established by the Superintendent;
   (F)   Any waters or wastes containing phenols or other taste- or odor-producing substances, in such concentrations exceeding limits which may be established by the Superintendent as necessary, after treatment of the composite sewage, to meet the requirements of the state, federal or other public agencies of jurisdiction for the discharge to the receiving waters;
   (G)   Any radioactive wastes or isotopes of a half-life or concentration as may exceed limits established by the Superintendent in compliance with applicable state or federal regulations;
   (H)   Materials which contain or cause:
      (1)   Unusual concentration of inert suspended solids (such as, but not limited to, Fullers earth, lime residues) or dissolved solids (such as, but not limited to, sodium chloride and sodium sulfate);
      (2)   Excessive discoloration (such as, but not limited to, dye wastes and vegetable tanning solutions);
      (3)   Unusual BOD, chemical oxygen demand or chlorine requirements in such quantities as to constitute a significant load on the sewage treatment works; and
      (4)   Unusual volume of flow or concentration of wastes constituting a "slug", as defined herein.
   (I)   Waters or wastes containing substances which are not amenable to treatment or reduction by the sewage treatment processes employed, or are amenable to treatment only to the degree that the sewage treatment plant effluent cannot meet the requirements of other agencies having jurisdiction over discharge to the receiving waters.
(1967 Code, § 17-59)  (Ord. passed 9-7-1983)  Penalty, see § 51.99