Accessory swimming pools, open and unenclosed, may occupy a required rear or side yard provided the waters edge is not located closer than four (4) feet to a rear or interior side lot line. Adequate hand holding provisions shall be made for pool entry and exit. Every swimming pool shall be protected by a safety fence or barrier approved by the director of safety and permits. A walk space at least three (3) feet in width shall be provided on two (2) side or fifty (50) percent of the exterior of the pool, whichever is greater, between the pool walls and protective fences or barrier walls, as per sketch.