Every person in possession of land within the City, either as owner, purchaser under contract, lessee, tenant, or licensee, upon which is situated a swimming pool, shall at all times maintain on the lot or premises upon which such a pool is located, and completely surrounding such pool, lot or premises, a substantial fence or other solid structure not less than five feet in height, with openings, holes or gaps therein no larger than four inches in any dimension. Any wall of a single-family dwelling, duplex apartment building, may be used as part of the enclosure. The vertical clearance from the ground to the bottom of the enclosure shall be no more than two inches and the outside surface shall be free of protrusions, cavities, or other physical characteristics that would serve as handholds or footholds that could enable a child below the age of five years to climb over. Doors and gates in these walls shall meet the requirements of CVMC 15.48.030. (Ord. 2724 § 1, 1998; prior code § 29.2).