Tarp under a pool? Site Prep question. Installing on a hill

SCarolina

Member
May 20, 2019
22
Belton, SC
We have been trough a tough time getting the site ready to install our pool. The area is a slope and its graded so the water coming down the hill will go around the pool, but the soil is clay and the flat pool base got soft when it rained. We had a contractor install a french drain to handle rain right around the pool, and put down a geotextile underlayment. Then then we put about 4 or 5 inches of 57 stone to raise the pool off the clay. At this point we let the contractor go and hired a new contractor to spread several inches of gravel dust on top of the packed gravel. He placed install patio blocks in the gravel dust for the uprights. This new contractor insisted that we would need a layer between the gravel and the gravel dust, or the rocks would come up, and he put a blue tarp!! on top of the gravel but under the gravel dust! His concern about the rocks is valid, but I am afraid the tarp will cause us more problems than it solved. I was thinking it would hold water and cause the pool to wash out from any little splash or small leak. We are so sorry we decided to install the pool! The summer is passing us by, and we want the pool up, but we also want it to stay up for years. Should we remove the tarp? Try to poke holes in it? Not worry about it? I was imagining that the gravel dust would form a packed layer but it is kind of soft and footprints sink in. I imagine it will filter down into the rock and rocks will come up without it. Any idea what to do at this point? Thanks.
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
41,027
Tallahassee, FL
Those blue tarps are NOT water proof by any means. If you hold one up in front of a light you will see how "woven" it is and how you can see light through it.

Once the water gets in the pool it will compact the sand or what every you have under the pool.

Kim:kim:
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
41,027
Tallahassee, FL
Yes I do. Move on with the build. To help your mind accept it please find a tarp to hold up to a light to see what I am saying. It is NOT waterproof.
 

jimmythegreek

Bronze Supporter
TFP Guide
Aug 10, 2017
1,268
Morris Cnty NJ
With clay you want some 57 stone actually in the clay to bind it up. You will be fine just get the stone dust compacted before you set up the pool with a plate compactor or even a hand tamper. Tarps are not waterproof it's just going to rot away with time keep going with the setup
 

d_red1

Well-known member
Jul 21, 2016
59
Keller, TX
Post some pics if you can. It sounds like he already installed the tarp between the 2 aggregates? I understand what he is trying to do but he went the mickey mouse route. Instead of a cheap blue tarp, he should have used another layer of geofabric that will allow the water to pass but not the fines. I think you will be fine as those tarps are not very durable and the sharp edges of the rocks will wear some additional holes. I do like your idea of poking some holes into it. May just on a 4' x 4' grid using a metal stake or piece of rebar for some additional peace of mine.