Partial bury or retaining wall WWYD?

eyedoc_01

Well-known member
May 30, 2020
56
Saint Louis MO
Hi all,

I did not plan out our above ground pool installed as well as I should have.

We have a sloped yard. Was thinking about putting up a retaining wall but cost will be expensive and will take me a long time. And our soil is almost all clay and so will slide down around the pool with any amount of moisture.

Plan A would be to dug it back and put in a retaining wall. Pros as I see it are less stress on the pool when we eventually drain it for a liner.

plan B is to partially bury the pool. It’s all resin and rated for burial up to 24 inches. Which is just about where the slope of the yard would take it. Pros are easier install, we have extra clay to get rid of that we could use for some backfill.

speaking of backfill whether we go with wall or partial burial I was planning on putting perforated drain pipe at base of wall or pool and covering with gravel up to grade. Would I wrap the perforated 4 inch in landscape fabric? Is it OK to put sod on top of that gravel drainage chimney either way? Does clay work its way through the gravel layer and mess with drainage down the road?

High side to the left, low to the right. Water and mud everywhere. At least the Labradors are happy :)
 

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TonyM

Well-known member
May 11, 2012
112
Middle Tennessee
My pool is partially buried (was installed by previous homeowner) and, if I had it to do over, I would not do the same. If and when you change the liner the dirt will push in on the wall some and if the wall pulls away slightly from the packed backfill dirt, rocks or the wall itself will crumble a little creating a "high spot". When you go re-fill, it might leave that "hump" in the wall if it is too much that the water cant push it back to shape. This can lead to wrinkles in the liner on install, if the pool cant go back to round, etc. Ask me how I know this.

Don't get me wrong - it works fine and I just came back from brushing the walls and the pool was just as happy as it could be... but come liner replacement time, I will again wish that the whole pool was at ground level.

So much so that i am seriously considering digging it out before the next liner....

That doesn't mean you have to go with a retaining wall, though - or, at least the full height one. Good grading, adding berms and swales and putting good ground cover on it (fescue or any type of good grass will do) will keep the water going where you want it.

And I am a huge fan of relocating ground water above ground instead of underground. Water wants to take the easiest path, and with a little grading, some planned landscaping in the right spot will keep you looking good. The black perforated pipes will fill with clay faster than sun eats chlorine, so plan to dig it all up in a few years if you go that route.

Looking at the picture really shows how close MO and TN are - Our clay in this area is some serious stuff :)
 

eyedoc_01

Well-known member
May 30, 2020
56
Saint Louis MO
Yeah, my head keeps telling me to spend the rest of the summer building a retaining wall, but my heart just wants to partial bury and get to do more swimming!

For the perforated pipe do you think it will fill with clay if I wrap it in heavy duty landscape fabric and backfill over it with gravel all the way up to grade? Does our lovely Midwest clay eventually seep through the gravel?

FWIW I grew up on a small farm in Indiana that was 90% clay soil with a little sand patch in one corner. I know about getting muddy :)
 

TonyM

Well-known member
May 11, 2012
112
Middle Tennessee
You definitely want to use rock with the perforated pipe, but I would not wrap the pipe with the fabric. What you want is to keep the dirt out of the pipe and the rocks, so think of the fabric as the "dirt barrier". The same clay that will plug the pipe will also plug the rock in the same manner, keeping the water from going down where you want it. So, the rocks and the pipe get wrapped in fabric. I would bring the rock all the way up (no dirt over the rocks and pipe at all). Go with at least 3/4" or larger rock - the larger the stone the better the flow.

The 2 main problems with the black perforated pipe is that it is hard to keep it "going downhill" and that you really have no effective way of cleaning the pipe. Since it is flexible, it is difficult to keep small dips from forming in the pipe, acting like a trap - especially if heavy clay soil is pressing down on it. Water will then go into the pipe but settle in these low spots. Any dirt or debris will also settle there, eventually filling up the pipe at that spot.

If I have to drain with perforated pipe I would go with rigid PVC, as it is easier to keep on proper grade, it is smooth-walled and you can add clean-outs in different locations. Unfortunately, trying to use hard pipe around a round pool is not too fun :)

So, if you go with the perforated make sure you line the trench with fabric, put a couple of inches of rock under the pipe (holes down, unless the pipe has holes 360 degrees around the pipe), 1% drop on the pipe (pipe should drop at least an inch every 8'), and try to take both ends of the pipe to daylight if at all possible.
 

eyedoc_01

Well-known member
May 30, 2020
56
Saint Louis MO
Thanks all, we have the pool up and running and are still deciding on the wall vs. backfill. Wall will cost around $8-9K. Ouch. We could get a nice deck for that.

For partial bury I would hire someone to backfill using pipe at the base of the pool, 18-24" of gravel (both deep and wide), and wrapping the pipe and gravel in fabric to keep the clay back from the pool directly. The contractors seem to think the gravel will mostly push down and not in on the wall as much as clay right up against the pool.

Only other issue is then for safety we have to buy some of those fence pieces that fit on the pool rails to raise the height of the pool barrier back to 48".

And then on top of the gravel we put rounded river rock. Waiting on quotes for that, as I am kind of over construction in the Saint Louis heat.