The Board, at their discretion, may require the owner of any property served by a building sewer carrying industrial waste to install suitable control manholes in the building sewer to facilitate observation, sampling, and measurement of the waste. The manholes, when required, shall be accessible and safely located and shall be constructed in accordance to plans approved by the Board. The manholes shall be installed by the owner at his expense and shall be maintained by him so as to be safe and accessible at all times. (Ord. 2858-1973) Penalty, see 10.99