I was 20 months old my mother would have been 8 months pregnant with my little sister.  As well as this pool I would have had a sandpit too.  It was in a concrete pit that one day had been a goldfish pond.  When we went to live in the house I grew up in Dad decided it wasnt safe and drained it and made it into a sand pit instead.  It was an awesome sand pit about 6 foot by maybe 4 foot with a depth of maybe about 2 or 3 feet in depth.  We had many years of fun playing in it.  At night it had an iron cover made of roofing iron sheets joined together with wood over it.