Hello… I am I the process of making my above ground pool into a semi inground. I am only planning to drop it the allowed 2 feet… my property is flat and after about 1 foot… the soil has sand. I was told that I don’t need a retaining wall. Then someone said that I had too. Another person said it should be ok if I left space between the pool and soil and not fill it with backfill…. My question is. It is a composite resin pool so I hope to get a decent amount of years from it. I also want to do it right and not have it implode , if god forbid when I change the line down the road. And if a wall is necessary. Would pressure treated wood be enough or do I have to go with cement blocks…. My original goal was backfill and then something around it so toys/pool stuff or even animals fall in between the space… any advice would be appreciated… thank you in advance.
Retaining wall? Is it needed on a semi inground and flat surface
- Thread starter Tysonyoshi
- Start date
Hey Tyson and Welcome !!!
If it's rated for burial, that's the depth it can handle without a retaining wall.
If it's rated for burial, that's the depth it can handle without a retaining wall.
- Jun 1, 2018
- 16,000
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
What pool are we discussing?
You say it is resin- are the walls resin or just the uprights/supports/top rails?
If you backfill you likely don’t need a retaining wall unless there’s some kind of other slope involved. The pool, once full of water, will prevent a dirt collapse.
If you don’t backfill you will want a retaining wall or a collapse of the soil could happen.
Either way its a good idea to add drainage to ensure you’re directing water away from the pool. A simple French drain.
Unless the walls are resin having earth on them will speed up the rust potential so take that into consideration.
Some folks here have elected to add additional waterproofing to the buried portions such as rhino liner type coatings etc. to help stave off moisture getting to the metal walls.
Once buried you should not drain the water below the surrounding ground area or your risk collapse. This makes liner changes a risk. The longer you can go without a liner change the better.
Doughboy pools recommend a slurry mix for backfilling for this reason.
You shouldn’t backfill until the pool is full.
If using soil to backfill it can take quite a while (many rounds) of backfilling & letting it compact. Every time it rains it will get more & more compacted. You want to ensure it’s fully compacted before adding a deck.
You say it is resin- are the walls resin or just the uprights/supports/top rails?
If you backfill you likely don’t need a retaining wall unless there’s some kind of other slope involved. The pool, once full of water, will prevent a dirt collapse.
If you don’t backfill you will want a retaining wall or a collapse of the soil could happen.
Either way its a good idea to add drainage to ensure you’re directing water away from the pool. A simple French drain.
Unless the walls are resin having earth on them will speed up the rust potential so take that into consideration.
Some folks here have elected to add additional waterproofing to the buried portions such as rhino liner type coatings etc. to help stave off moisture getting to the metal walls.
Once buried you should not drain the water below the surrounding ground area or your risk collapse. This makes liner changes a risk. The longer you can go without a liner change the better.
Doughboy pools recommend a slurry mix for backfilling for this reason.
You shouldn’t backfill until the pool is full.
If using soil to backfill it can take quite a while (many rounds) of backfilling & letting it compact. Every time it rains it will get more & more compacted. You want to ensure it’s fully compacted before adding a deck.
The short answer is maybe
The long answer is it depends
Seriously though, soil is not soil is not soil. You cannot just make a blanket statement that you need a retaining wall or not. It depends on both the soil, the groundwater conditions, and the pool itself.
A swag, for many soils and gravels is 60 pounds per square foot per foot of depth for at rest pressure and 30 psf for active pressure. A short (less than 8') wall is normally designed for active pressure. So, barring any sort of water table, the pressure on the pool at 2 feet is going to be 60 psf. (30 psf x 2 feet of depth)
In *theory* if you have a round pool, and consistent loading, then it should be in static equilibrium.
Of the above assumes a full envelop of development. If the backfilled around around your pool is narrow enough, then the full envelop cannot develop, so the loading will be less.
All of this is just to say, nobody can tell.
My gut is, in most circumstances, 2' of fill will be fine as long as it is a well drained area with well drained fill.
The long answer is it depends
Seriously though, soil is not soil is not soil. You cannot just make a blanket statement that you need a retaining wall or not. It depends on both the soil, the groundwater conditions, and the pool itself.
A swag, for many soils and gravels is 60 pounds per square foot per foot of depth for at rest pressure and 30 psf for active pressure. A short (less than 8') wall is normally designed for active pressure. So, barring any sort of water table, the pressure on the pool at 2 feet is going to be 60 psf. (30 psf x 2 feet of depth)
In *theory* if you have a round pool, and consistent loading, then it should be in static equilibrium.
Of the above assumes a full envelop of development. If the backfilled around around your pool is narrow enough, then the full envelop cannot develop, so the loading will be less.
All of this is just to say, nobody can tell.
My gut is, in most circumstances, 2' of fill will be fine as long as it is a well drained area with well drained fill.
Agree 100%. But if an established manufacturer is certifying it can be buried to X depth, we can assume they have tested it in the extreme conditions possible to avoid being held responsible.
I'm sure there is an exception to this rule as there are with any rules, but for most it should suffice.
Under normal circumstances, yes. But I would read the fine print. It may say something like if changing a liner the pool can only be empty for 3 hours or something like that.
I am just envisioning the situation where it is a soil with the lowest angle of repose, the user drains the pool, removes the liner, and then an emergency happens and they get called away. Then it pours rain.
- Jun 1, 2018
- 16,000
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Generally the rule of thumb is that the longer it’s been buried the better when liner change time comes. The surrounding soil should be well compacted after several seasons and pose less of a collapse risk. Being expedient along with doing the liner change during a dry spell is the best bet. If the pool needs to be left empty it should be braced- this holds true for all above ground pools.