I have a 20'X 36' inground pool that is 15 years old and the patio section at the deep end is beginning to sink. I'm not sure if it was caused by ongoing rain or rotted tree stumps buried when the house was built in 1993. The back of the patio is sinking which is making it lift at the pool edge which is lifting the coping and putting stress on the liner. I cut the concrete at the pool edge to take the stress off the liner.

I'm not sure of the best approach to repairing this in the Spring. One thought is to break up the section of patio and excavate and see what's causing the problem. I have already started to receive estimates and they are all over the place with 1 contractor telling me that I should consider replacing the entire pool patio at a cost of $12,000.00

Any suggestions is much appreciated.