River Sand Foundation A Mistake?

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mchead22

New member
Jun 19, 2024
3
Baton Rouge, Louisiana
Hey all, new to pool ownership and new to the forums. I decided this year to buy a 12x24 Intex AGP. Last weekend we cut the sod, rented a skid steer to dump all the sand in the area, and then leveled it all out. This is in southern Louisiana in the 96 degree heat, so it was a hard day and I took Sunday off to recovered. I'm all pumped to build the pool this weekend but..... now I'm starting to worry I made a mistake. I used river sand as my foundation, and its not compacting very well. I put my foot on the outside border today where the pool will not go, and with even the slightest amount of pressure, I could feel the sand giving way to my footprint. Not to mention there's countless little twigs and debris mixed in...

Did I make a huge mistake?? Is river sand usable at all or am I going to have to go back to the drawing board?
 
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Welcome to TFP :)

River sand can be extremely coarse and is often used as the primary sand for mixing concrete. It is versatile for both commercial and residential projects. I would be concerned about the liner and puncturing it as well as developing voids over time. Intex style pools should never be installed on top of a pure sand base. It is ok to add an inch or so to level in some uneven spots (Yellow mason sand I think is best suited for pool use). These pools really need to be on virgin soil (my base consists of: soil > a little filler sand > Tarp > Foam Boards) that has not been disturbed using a compactor when dirt is needed to fill in the lower points. I also like putting down 1" pink foam boards. It helps with getting wrinkles out of the liner, feels nicer on your feet and takes some of the dips and high points less noticeable. In general, you want the pool to be within 1 to 2 inches (some say within 3 inches) of being level for safety.

The base of your pool is the most important as well as the most time consuming.
 
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Hi there - I would redo your surface. Level down to solid ground, digging out any high spots. You can use a thin layer of sand to smooth it out - maybe 2 inches. Depending on your soil, you might want to get a gorilla pad or similar. You can use foam boards, as mentioned above, but many of us don’t. It just depends on your preference and your soil.
 
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mchead22 said:
Hey all, new to pool ownership and new to the forums. I decided this year to buy a 12x24 Intex AGP. Last weekend we cut the sod, rented a skid steer to dump all the sand in the area, and then leveled it all out. This is in southern Louisiana in the 96 degree heat, so it was a hard day and I took Sunday off to recovered. I'm all pumped to build the pool this weekend but..... now I'm starting to worry I made a mistake. I used river sand as my foundation, and its not compacting very well. I put my foot on the outside border today where the pool will not go, and with even the slightest amount of pressure, I could feel the sand giving way to my footprint. Not to mention there's countless little twigs and debris mixed in...

Did I make a huge mistake?? Is river sand usable at all or am I going to have to go back to the drawing board?
Click to expand...

How thick is this layer of sand?
 
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I honestly just do not think you will be able to compact the sand enough with that much depth. Will wait on those that are more experienced with the engineering/technicalities to offer
@newdude @Texas Splash can you provide or tag anyone for a deeper understanding?
 
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I would not use that thickness of sand, nor would I use it to build up the side that slopes down. You are going to lose sand that way, and risk your pool collapsing.

Dig down to lowest level of undisturbed ground and level all the way around.
 
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mchead22 said:
About 3-5 inches. It gets thicker towards the back as the yard slopes down a bit.
Click to expand...

That is too much sand. Sorry to tell you that.

Sand has an angle of repose of 30 degrees or so, and as a poorly graded material does not lock together well. You have river sand, which is a plus, as it is angular as opposed to smooth, but it is not a material you are going to want to use anyway.

That sand is likely going to wash out over time, causing problems. Building a "retaining wall" or similar structure will not likely be of help either. 5" lifts are a bit too much to compact with tools that homeowners have access to at rental shops. The real issue with compacting fill though is moisture content. I have gone into detail about this on a number of other posts here, but the take away is, you will never get any soil compacted to its' maximum density, no matter how hard you compact it, unless its moisture content is correct at the time of compaction. And you do not know what that optimum moisture content is unless you run a series of tests on that particular soil to determine it. And you don't know if your fill is at the right moisture content unless you measure it. And then even after all of that, you don't know if you compacted it enough unless you measure the compaction. If you don't do that, you are basically guessing that it is not going to settle at some point in the future.

I hate to be the bearer of bad new, but the right move here is to get the skid steer back, remove the sand and put it in a pile. Then level the pad by cutting out the high side, so the whole pad is level on undisturbed ground. Then spread a inch of sand (if that much) over the undisturbed soil for a final level / cushion - and if you have twigs and debris in your river sand, sift it out and get a new masonry supplier.

You can top dress your lawn with the left over sand - or make a sandbox for the kids. (I hate sandboxes, they attract the neighborhood cats, if you know what I mean)
 
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