In any property served by a side sewer carrying industrial wastes when required by the City Engineer, the owner or occupant shall install a control manhole in the side sewer to facilitate observation, sampling and measurement of the wastes. The manhole shall be accessibly and safely located and shall be constructed and installed in accordance with plans approved by the City Engineer. The manhole shall be installed and maintained by the owner or occupant at his sole expense. (Ord. 208 § 34, 1957).