New AGP constuction and clay soil.

[kyk96]

Hi!

I am preparing to install a new 24 ft round AGP. I have been doing a lot of reading, and see different ideas and opinions on the best way to go about this. We live in SE Michigan and have heavy clay soil (the kind that will stick in a 5 pound clod to your boots when it's wet and you need a jack hammer to dig when it's dry!).

I would like to dish out the middle slightly. I am wondering what the best foundation for the base plates and rails would be. Should I level the area and build up a wide ring of some sort of crushed stone foundation and use a gas powered tamper to compact it? Could I get it solid enough this way? I always hear dig down, don't build up. Should I set the base plates with patio blocks, without patio blocks? The manula says to use them, but then it also says not to install. the pool on clay!

I just want to have it all figured out so that I am ready when the time comes. Impatient wife and 8 yr old are waiting to swim!

 

[Tim23]

Hello KyK96,

Well.... I just went through this exact problem. The area we put our pool was all clay. Here in S. Louisiana we fight with either a soupy mess or so hard that you can't dig it at all. I got some real good advice here. What worked for me was to mix portland cement in the soft clay around where the rails and pads go. By mixing the cement and clay it made it hard and workable at the same time. What I did was to till the area where the pad and rails go and tamped that back out and leveled it. I let it sit for a day or so until it was hard enough to dig and set my pads.

Our clay was so soft that if I stood on a pad it would sink from my own weight. Now keep in mind we had a bunch of rain while we were clearing the area where the pool was to sit so it stayed wet a bunch. All this said it worked out well and everything hardened up well and no problems since. Make sure you use the pads... I also put crushed rock under each pad to help make it more stable. You can buy the crushed rock from Home depot. If the ground is really soft make a pyramid with the pads. Two on the bottom and one across the top. Its a little more work but at you will feel better in the end. My kit called for 2x6x8 pads. I hope this helps some. I'm sure these great people will give some great advice also.

Here is the link to a post where I ask the question... soft-spots-in-clay-t18598.html

Tim

 

[kyk96]

Hi Tim,

Thanks for the input. I like this idea, may be worth a try. The only thing that still concerns me is that we are of course in a heavy frost zone, so I am concerned about heaving of the clay. So I am wondering if I should use a combination of methods to make sure things are really stabilized. Hopefully, you don't deal with this too much where you are (although this winter I think you probably saw some cold temps!) I really only want to do this once! Thanks again!

 

[Tim23]

kyk96,

Yeah this year we had snow 3 times!! I have lived here all my life (I'm 43) and that was more snow then I have ever seen. So that being said I am not sure about your freeze line where you live. We tilled down about 2 feet or until I hit hard clay. Once I tilled it we added in the portland cement(no rocks) and tilled it into the clay and added some sand at the same time. Like I said in another post the area was hard because we had another pool in the same spot. It wasn't until I removed the old sand and grass for the larger pool did I run into the problems.

After I tamped it back out, wet it down in the areas that weren't already soft or wet then the clay hardened up and was workable. So I did the whole area where the pool rails would sit about 2ft wide. This did the trick. I was no longer worried about any soft spots or sinking but I could still dig it to level it. One other thing is I did a test area before all of this.... I tilled up an area, tamped it, then covered it with a tarp because rain was coming then I added about ten pads on that spot to see if they would sink. I also covered the rest of the area of the pool base.

After the rain ended the next day I removed the tarp off the main area where I hadn't done anything to and it was like mush. In the area I had tested..... Pads never sank, and the area although wet was still hard. So that was good enough for me.

I have only had the pool up for about a week now and no problems even with rain around the area that I haven't backfilled yet. So I hope you have the same success I did. Any question just ask.

Tim

 

[kyk96]

I am wodnering if I should just bring in a big load of road base type stone (crusher run) and cover the whole area. I saw one post that mentioned this. Or maybe just a ring about 3-4 ft wide that the bottom plates and rails would be centered in? Would this work? Then I could dish the middle a little for more water depth. How deep a layer would I need? Would this be enough to avoid frost heave in our clay? I would of course use a vibrating plate to compact everthing. So many questions! The pool site is pretty low, so maybe getting the bottom hardware up off of the leveled clay ground. I am still having nightmare about the old pool we ripped out and how bad all the bottom hardware was that I couldn't see when I agreed to buy it!

Does anyone have any suggestions on all of this? I am a little freaked out 'cause I want to do this right the first time and not have problems later.

So let me know what y'all think. Thanks!!

 

[Kias]

I am still having nightmare about the old pool we ripped out and how bad all the bottom hardware was that I couldn't see when I agreed to buy it!

That was my biggest fear when I agreed to buy the one I'm working on. I must of just got lucky, as it wasn't in that bad of shape!

You also have a PM if you didn't notice! :-D

 

[kyk96]

Hi everybody,

The trail went cold on this post I guess. It's getting close to the time to start ground work! Does anyone from a heavy frost/snow area with clay soil have further ideas or experienece for ground prep? I could really use the advice. Thanks in advance!

 

[Tim23]

Hey kyk96,

I'm just curious, what does the frost do to clay in your area? Is it because it freezes and then thaws out and gets soft? I'm just wondering because here in Louisiana the frost line is very shallow. We have more of a problem with the water and clay here then with the freezing problem, even though we had the coldest winter here in a long time.

I'm still thinking that mixing some portland cement in with the clay will hold it together even with the frost. The pool will be covering the area that would be exposed to frost, rain etc.... I know when we took down our 24' intex pool to install the new AGP the ground was hard as a rock under it even though the ground around the area was soft from the rain. Like I said before it wasn't until I disturbed the ground under the old pool and exposed the clay to the rain did I have major problems.

Its like in a yard where you have grass growing it seems really solid even when somewhat wet. If you remove that grass in the same area and it gets wet you end up with soft mud. The roots keep the soil intact and provide support. By no means am I an expert but I know what I did worked for me. Trust me when I say for a while I thought we were never gonna be able to install our new pool because I couldn't get the clay to dry or harden due to all the rain etc...

I'm guessing you are worried about what will happen after the your pool is installed? I wish you luck and I'm sure someone here will know more about the frost effect in your area.

Tim

 

[kyk96]

Hey Tim,

Yeah, the thing that concerns me is the frost heave once the waterlogged clay freezes. I know what you mean about taking forever to dry out the clay. I am waiting for that right now so I can get started on leveling. I am mostly just worried about the bottom rails and verticals after a few seasons of water absorption and freezing/heaving. I have seen a few pools in our area that have many verticals out of plumb and I am wondering if this is what caused it. Then the whole question of blocks or no blocks! I will probably use them though. I like the portland cement idea, but I would have to rent a rototiller. I already know I will have to rent a vibrating plate. Whew, sounds like a lot of work heading my way! Take care.

Kip