new vinyl lined in ground pool has 2 foot long cavein under pool base


New member
Jul 22, 2019
hello all.... i am totally new to pool ownership. in fact am having first ever pool built as we speak.
pool builder came to me to show me that after they have put down the vermiculite and dropped the liner in there is now a small cave in near the bottom of the pool but on a vertical wall. they ran into ground water during the dig and had to add 16 tons of rock to the deep end to control it.
they say that they will drain the water out of the pool to below the cave in and pull the liner back and redo the vermiculite then reattach the liner and refill the pool. it scares me to think that this could happen again... has anyone ever dealt with this and do i have anything to worry baout?
Thanks so much for any input on this!!!!


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
Welcome to TFP!

Hate to hear about your troubles. Best I can offer is that once you have water in the pool it will PROBABLY stabilize things. Sounds like the builder is on it


In The Industry
Apr 1, 2018
Bangor Maine
In wet areas, small cave ins or indents are very common. If he uses the proper substrate and proper depth they can be minimized. Think of your driveways or our highways, they can be made perfectly smooth but most times the amount of aggregate is way too expensive. He should of known this beforehand and properly quoted it.


TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
Morris Cnty NJ
Groundwater is common while building pools. How its dealt with separates the pros from the hack installers. I've seen this happen on the main drain piping channel up the side wall in deep end. Sound like you may have that same issue. He should have planned for stone anyway. Unless you have a dry hole thru excavation stone should be used to bind and stabilize the sub base.