I have a 1965 Hallmark pool. At least I have been told that is what it is called. It has a concrete bottom, and fiberglass walls. The walls also have joints in them, where it looks as though they layed the bottom, then brought the sides in as premade pieces and then put them together. It also has a safety ledge all the way around. Well it seems that parts of the pool have risen as much as 3 inches out of the ground. Some of the pipes were left behind.. My grandparents said it was already like that when they moved in. Is this typical of hallmark pools? I know that the previous owners had cemented down the release valve.. and I have been in the pool biz for about 7 years now, and cant figure out why someone could be that stupid after just having payed for an inground pool. But even after my grandfather removed the cement, I guess it still rose up a bit here and there. They never left it empty or anything. I guess that I am just wondering is there would be any other reason something like this would happen to a pool that had only been there for ten years.