(1) Flammable or Explosive Material. Any gasoline, benzene, naphtha, fuel oil, or other flammable or explosive liquid, solid, or gas.

(2) Toxic or Poisonous Materials. Any waters or wastes containing toxic or poisonous solids, liquids, or gases in sufficient quantity, either singly or by interaction with other wastes, to injure or interfere with any sewage treatment process, constitute a hazard to humans or animals, create a public nuisance, or create any hazard in the receiving waters of the sewage treatment plant, including but not limited to cyanides in excess of two mg/L as CN in the wastes as discharged to the public sewer.

(3) Corrosive Wastes. Any waters or waste having a pH lower than 5.5 or having any other corrosive property capable of causing damage or hazard to structures, equipment, and personnel of the sewage works.

(4) Solid or Viscous Substances. Solid or viscous substances in quantities or of such size capable of causing obstruction to the flow in sewers, or other interference with the proper operation of the sewage works such as, but not limited to, ashes, cinders, sand, grease, mud, straw, shavings, metal, glass, rags, feathers, tar, plastics, wood, unground garbage, whole blood, paunch manure, hair and fleshings, entrails and paper dishes, cups, milk containers, etc., either whole or ground by garbage grinders.

(5) Excessive BOD, Solids or Flow. Any waters or wastes having (a) a five-day biochemical oxygen demand greater than 300 parts per million by weight, or (b) containing more than 350 parts per million by weight of suspended solids, or (c) having an average daily flow greater than two percent of the average sewage flow of the city, shall be subject to the review of the superintendent. Where necessary in the opinion of the superintendent, the owner shall provide, at his expense, such preliminary treatment as may be necessary to (d) reduce the biochemical oxygen demand to 300 parts per million by weight, or (e) reduce the suspended solids to 350 parts per million by weight, or (f) control the quantities and rates of discharge of such waters or wastes. Plans, specifications and any other pertinent information relating to the proposed preliminary treatment facilities shall be submitted for the approval of the superintendent and no construction of such facilities shall be commenced until said approvals are obtained in writing. [Code 1975 § 3-3.0302.]