Backfill advice

[Redfive]

Hi Everyone, I have read the forums and learned a bunch and was hoping to get a bit of advice from the great folks in this community. I have an new in-ground vinyl liner pool going in. We have a high water table where i think it comes up to 3 feet at points of the wet season. We also have sandy soil that drains really well.

In digging our deep end we hit water at around 8ft which seemed like it was going to be manageable but unfortunately with the sandy saturated soil the hopper broke away and we decided to bring the bottom up. Long story short, the deep end is now at 5 feet filled with 4.5 feet of crushed stone as is the slope up to the low side at 3.5ft.

My concerns are twofold. The liner floating, and a good base for a paver patio in the spring. Given how much crushed stone will be under the pool which I assume will decrease static pressure and drain well, should backfilling with the sandy soil from the excavation suffice, or will I regret not using crushed stone down the line? I live in New England where we get pretty cold winters as well.

Thanks in advance for any advice!

 

[BMK]

Welcome!
I'm no expert, but I'm sure others that know more than I will be along soon. That said, it is my understanding that stone backfill is always preferable over excavated soil.
Not knowing any better at the time, I remember during our build asking my PB if after the footers were poured and the french drains were in place, they were going to backfill with the excavated dirt. He just gave me that "I'll pretend I didn't hear that" look and muttered the word 'never' as he walked away.

 

[phonedave]

My friend has the same situation - in ground liner pool with a very high water table. He also has a paver patio around the pool. When he had his pool re-done, the PB backfilled with crushed stone.

You really should have some dewatering points installed. These are pipes that will go down under your pool. When you need to do a liner replacement you connect a pump to this lines and pump the ground water down. No, this does not drain out all the groundwater, what it does is create a depression in the water table localized at your pool. You have to keep the pumps running the whole time while changing the liner.

As an aside, I don't know if you are considering a heater or not, but a pool with groundwater that high all around will suck any heat from the sun right out of your pool.

 

[duraleigh]

If your groundwater is at 3 feet, your liner will probably float regardless of the type fill.

However, there is NO substitute for a good base......use rock. The best one IMO is #57 washed stone. Please do not use the excavated soil.

Secondly, can you get a French drain around the perimeter at the base of the pool. You can solve most ALL your water problems if you do that.

 

[Serious1]

We did drain tile with a well point/basin. We pump the water out with a sump pump when the pit is full because we're too lazy to get a sump pump with a float that will fit in the hole. It gets full when people up the hill from us run their sprinklers a lot...not just when it rains.

 

[Redfive]

Thanks for all of the advice. We do have a wellpoint under the deep end that I will have access to pump from. We also have a crazy amount of crushed stone in the deep end. I'm talking 4 or 5ft deep and probably like 16ft x 16ft square, as well as crushed stone sloping up to the low side. The water table right now is at about 8 ft and that was after 2 days of torrential rainfall. The soil does clearly show it up to 3 or 4 feet at times though (spring I assume). Really hoping the liner wont float, but only time will tell I guess. The bright side is that our soil is very very sandy and drains extremely well.

 

[jimmythegreek]

the only bad thing w the well point under the deep end is that YOU have to know its high and valve the pump to pump the water out. It would have been easy to add a well point w 10"pipe up the side and have a sump pump w vertical float running 24/7 on the ready. I have high water and did a drain around the pool on top of footing to 2 of my 3 vertical sump pits and I have pumps in all of them keeping water down. When I finish the decking I will raise the pumps up 2-3ft and allow some ground water to naturally rise and fall but keep it 3ft max from top of pool. You have to get pretty high saturation and water level to get a float of liner but it DOES happen, with good draining soil it will be better but be careful that the surrounding earth is also good draining. if you have a hill nearby or are in low area the good draining soil will bring the water to you instead of away from you