During operations permitted under this chapter, any area where collections of water are one and one-half feet (11/2') in depth or more, or where excavation slopes are steeper than one foot (1') vertical to one and one-half feet (11/2') horizontal, and any other areas where obvious danger to the public exists, shall be fenced when such a situation has existed or will exist for a period of five (5) working days or longer. The city engineer shall review such fencing to assure its adequacy. He may waive this requirement or require additional measures based on his judgment and the characteristics of the particular instances. As an alternative, the city engineer may require perimeter fencing of the entire extraction site. (Ord. 375, sec. 1, 5-1-1989)