Above ground and slope

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archjeb

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May 22, 2017
68
Portland/OR
Hello folks,

New here and thinking of installing an above ground pool on a slight slope. I just poured a concrete slab / patio (as you can see in the picture) and would like to place the pool in the adjacent area next to the concrete. Since its a slight slope, I'd need to build it up a little and compact it.

I wanted to bounce the idea off of you all to see if my thinking is sound. I thought I'd go and buy some of those stackable concrete retaining wall blocks around the entire area that needs to be raised/leveled. Then place some 3" minus base rock - use a motorized compactor, then place some 3/4" minus and compact. Finally, place a layer of sand compacted. Debating on using the foam pads or not between the sand and liner.

The deal is, the soil is clay and can be mushy when wet. I was thinking of the compacted 3" rock as a base and then gravel and then finally a generous layer of sand.

Any thoughts about doing this?

I'm I crazy to think 3" rock for base, or just go with some 3/4" and then compacted sand on top? As far as height in the middle, it will only be about 10" tall as far as the retaining wall.

Any suggestions appreciated.
Thanks in advance.

-Jpool-area.jpg
 
How big of a pool are you considering?

How close will the pool be to the retaining wall you already have? Here in NJ you have to have at least 3' away from raised ground so someone can't just jump over the side into the pool. It doesn't look like a lot of space right off the patio but can't tell in this picture.

Another thing is you may void your warranty if your building up the ground under your pool. I was dealing with the same situation and decided to dig down to level the ground completely (my high side was 29" higher) as to not void my pool warranty for a improper install. I would check with your pool manufacture that doing this will not void your warranty if you care.

As to the method I can't give any advice, sorry.
 
The area is kind of deceiving based on the picture. Between the concrete and the boulder retaining wall its over 36' and width I have 48'.

As far as pools I'm thinking, I could go with a round 24 or 27'; ideally I'd go with an oval. Since I've never had a pool (just a hot tube) I have no idea what size or shape is better. We have a 9 year old; so something that the kids would enjoy.

The Costco Century Pool seems to be at a decent price. Any thoughts on that for this use case?
Century Pools Majestic Above Ground Resin Pool Packages

Thanks,

-J
 
Always better to dig your pool down to level and you can back fill up to 2' against a lot of above ground pools.

You will need to be very mindful of runoff and erosion in any heavy rains if for any reason you get water to undermine and scour out the fill under a support your pool can collapse in a big hurry.

What you are suggesting can be done and it sounds like you have a good starting plan. I did basically the same project last year you can see some of the steps in link to my build photos.
 
As was said, it is always better to dig down, than to build up. However you can build up if you have to. When building up, you need to make sure that you have compacted your fill correctly. It is not as simple as using the right material, and then running a "motorized compactor" over it. You need to knwo the compaction level of your underlying soil - "mushy clay" is not an ideal situation, nor is it an engineering description. You have to make sure that the moisture content of that soil is at a correct point before you begin to add fill. You have to make sure the mositure content of the fill is at a good point before compacting it. You have to compact in lifts, the thickness of which depends on the type of compactor you are using, and you have to construct an adequate retaining wall to resist the laterial pressures.

A pool puts a LOT over overburden on the soil. If you don't compact your fill correctly, your pool will.

-dave
 
I appreciate all the input.

I could dig down, but I'm not sure if that will buy me anything given the fact that this is all fill dirt that has been in place for 15 years. Its compacted over time given the 40+" of rain we have each year and driving a tractor over it. The challenge has been drainage because of the lack of permeable soil (clay). So that is why I was thinking the 3" rock base, compacted and then capped with 3/4" minus. I did that on my access road just above this location and just had a cement truck drive over it (to pour that patio in the back) and it didn't move one bit - solid and that was after 147 days of rain so fair this year.

Granted, a cement truck is only ~65,000lbs and a 24' pool is more than twice the weight, but its distributed over a 24' area vs the small area of the tires on a cement truck.

Additionally, I was planning on a French drain to get that rain water off the back yard better.

Thanks again for the feedback.

-J
 
Honestly I would just use road base (ie quary process, or 3"minus). Compact it in small lifts while keeping it damp then compact the finish area it over and over again. Having the right moisture in the fill is as important to getting it compacted as using the right compactor. You are going to need a lot of fill to lift that area 10". I did a lift the height of a green 6x6 and that took about 35 tons to fill. That material drains really well on its own if you put a drain around the lower edge of your wall the pad should drain really well. If you can do anything to divert run off away from the pool area that will help as well.
 

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To answer your question about the pool size/shape. You get more for your money with a round as oval is more expensive (for less space) to buy and install if your not doing it yourself. With one child a 24' round should be plenty with some added friends. That seems to be the popular size choice. My sister had a 27' round and when you got into it the size was surprising. You could easily fit 10-15 kids in a 27'. My friend has had up to 20kids in hers. If you are more interested in swimming the ovals are nice because you get the length but it doesn't take up your entire yard. For oval a 15'x26' or 15'x30' is probably plenty for most families. i struggled between the 15x30 an 18x33 and although the 15x30 would have been fine for our family of 5 plus a few friends I went with the 18'x33' so I could be well away from the splashing!
 
Folks,

I'm making progress here. In prep for the 24' round pool, I've laid down 3" minus and compacted this with a plate compactor after watering this down well between lifts.
I'm now working on 2" lifts of 3/4" minus and compacting each lift after watering it down. I'll get about 4" of 3/4" minus when all said and done.

Now the question comes down to what do I put after that to protect the liner? Obviously sand, but if my support is on a paver block which is flush with my 3/4" gravel, should I be thinking of actually compacting some other material before considering the sand? I'm also planning on laying down a pad and permanent cove for additional protection.

Thanks,
-J
 
Will the sand under the liner be on 3/4" gravel or will it be on compacted 3/4" minus?

If its on compacted 3/4"minus the 2" sand bed that normally goes under the liner will be fine. Get good clean sand with no rocks and small pebbles in it for under the liner.
 
CJadamec said:
Will the sand under the liner be on 3/4" gravel or will it be on compacted 3/4" minus?

If its on compacted 3/4"minus the 2" sand bed that normally goes under the liner will be fine. Get good clean sand with no rocks and small pebbles in it for under the liner.
Click to expand...

It is on compacted 3/4" minus and its within 1" level on all sides. (Picture attached)
I'm installing a 24' round pool, but I compacted the gravel in 2-3" compacted lifts at 32' diameter (to give me a solid 4' around the entire pool of compacted aggregate).

So if I plan on using the paver bricks for the supports and just raise the sand up 2" you think that will be ok?

Do you all use a compactor on the sand too, given that I'm planning on the pad below the liner?

Thanks,

Thanks,
-Jeremy
 
Last edited:
One additional question. 3/4" minus is still hard to get a perfectly flat surface. I'm thinking about putting a 1/2" to 1" layer of 1/4" minus and compact that. Any thoughts on applying that *before* the sand?
I just want to get things perfect before moving to the next step.

Thx.
-J
 
Alright, some more progress. I did a final 1" of 1/4" minus to cap and get a better level grade. I shot the area with a laser level and I'm within 5/8" all the way around. I'm going to get some of the paver bricks and start placing them and leveling them. Let me know if you have any other suggestions before I move to that step.

Thanks. (BTW, this is a lot more work than I anticipated... :) )

-Jbkyard-level2.jpg
 
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