No explosive or inflammable matters shall be discharged into any sewer.
Cleaning establishments, buildings used for housing or repairing automobiles, gasoline and oil service stations, and other buildings or establishments where gasoline, oils, calcium carbide or other explosive or inflammable matters are stored, sold, or handled, the frains from which are connected to the public sewers, must be provided with an approval intercepting pit or tank so constructed, located, and maintained as to prevent the entrance into the sewer of such explosive or inflammable matter.