(1)   Prohibited wastes.  Except as hereinafter provided, it shall be unlawful to discharge any of the following described waters or wastes into the municipal sanitary sewer system:
      (a)   Any liquid or vapor having a temperature higher than 150°F;
      (b)   Any water or waste containing more than 100 parts per million by weight of fat, oil or grease;
      (c)   Any gasoline, benzene, naphtha, fuel oil or other inflammable or explosive liquid, solid or gas;
      (d)   Any garbage that has not been properly shredded;
      (e)   Any ashes, cinders, sand, mud, straw shavings, metal, glass, rags, feathers, plastic, wood, paunch manure or any other solid or viscous substance capable of causing obstruction to the flow in sewers or other interference with the proper operation of the sewer system;
      (f)   Any waters or wastes containing a toxic or poisonous substance in sufficient quantity to injure or interfere with any sewage treatment process or which constitutes a hazard to humans or animals or creates any hazard in the receiving waters of the sewage treatment plant;
      (g)   Any waters or wastes containing suspended solids of the character and quantity that unusual attention or expense is required to handle materials at the sewage treatment plant;
      (h)   Any noxious or malodorous gas or substance capable of creating a public nuisance; and
      (i)   Grease, oil and sand interceptors shall be provided when, in the opinion of the city engineer, they are necessary for the proper handling of liquid wastes containing grease in excessive amount or any inflammable wastes, sand or other harmful ingredients; except that the interceptors shall not be required for private dwelling units which discharge only normal wastes therefrom. The grease and oil interceptors shall be of substantial construction, water-tight and equipped with easily removable covers which when bolted in place shall be gas-tight and water-tight. All greases, oil and sand interceptors shall be maintained by the owner, at his or her expense, in continuously efficient operation at all time.
   (2)   Industrial wastes. It shall be unlawful to discharge into the municipal sanitary sewer system any industrial wastes unless the prior approval of the city engineer is obtained. The city engineer shall approve the discharge of industrial wastes when, in his or her opinion, the proposed wastes will not be of an unusual amount or character. When in the opinion of the city engineer the proposed wastes are of an unusual amount or character, the city engineer may approve the wastes.
(Prior Code, § 402.07)