Dropping an Intex into a hill....the saga begins

[rckseattle]

Hello everyone. So grateful to have found this forum and community. My wife and I recently bought our first home. We worked our tail ends of the pas10 years to do it but before we ever had it I promised her a pool because she has always wanted one. Well now it is time to pay up! Unfortunately the house we fell in love with has a sloped back yard. I have been doing a ton of research and figured we had better call in a pro to build a retaining wall. After getting several "no's" from contractors who were too busy and a few quotes that were out of this world we finally found a local landscape guy that seemed to know what he was talking about, had good references and several projects he had previously done AND he could start right away! He came over and I went over everything I wanted to do so it was all clear, he explained a few things to me about what was doable and what wasn't gave me a quote that was reasonable. Then last weekend two days before he was supposed to start he brought his brother over to walk the site and come up with a game plan. Long story short all of a sudden the price increased $10,000!! I told them to get off my property and not to come back...ever! Then I decided....I'm going to do it myself. As with most things construction related I know most of the time I CAN do it, I just don't WANT to do it. However this project has me somewhere in between so I wanted to reach out to some of you folks who may be willing to offer up some advice or maybe even stop me from doing something disastrous. Either way I plan to document the entire process in the hopes that maybe someone down the road will benefit from this process.

So I wanted to share my though process of what I intend to do and share some pictures and updates along the way. So here goes...

So as I mention our backyard has a slope to it and it pretty much slopes across the entire expanse of the yard as it is a split level/daylight basement so the difference is elevation is roughly 8 feet or one story. At the low side there is about 10' of level ground that serves as a driveway area from our rear gate.

We purchased the Intex Ultra XTR Ultra Frame 16'x32'x52". Its ginormous. So what I plan to do is basically split the difference of the slope and dig out the top half to about 48" deep and adding that material to the low side. Then I will add a timber retaining wall all the way around the opening allowing for about 24" between the retaining wall and the pool itself. I plan on building this out of #2 and better pressure treated 4x4 posts set 18" in concrete with a 3" base of gravel in each hole for drainage. The wall material will be treated # Hem Fir Ground Contact Treated 2x10's. I considered using stone pavers to create the retaining wall but the material cost was 2x what timber will be and even the timber option isn't going to be cheap.

So I will be learning a lot of this as I go. Lesson one started today with how to operate a mini excavator and a skid steer! But hey - we have broken ground and nothing else. No power lines or sewer pipes were harmed during the making of this pool project!

If anyone has any words of wisdom they would like to share I would be grateful for all the advice I can get.

I will do my best to document as much of this journey as I can. Here are a few images of our yard to give you an idea of the slope and the first excavation pictures.

Stay tuned!

 

[Newdude]

Hey rS and Welcome !!!!

You need 2 retaining walls. You CANNOT build the low side up with fill alone. Come do some math with me. 4 ft water height X 16 X 32 X 7.481 gallons per square ft × 8.3 lbs per gallon equals 127,165 lbs.

The fill side would need to support 63,582 lbs if it was split down the middle half in half out. Would you ever put 21.75 tons on a pile of dirt and expect it to just sit there nicely ?

You can't even build up the ground on a pool that is off level by a few inches, much less a few feet.

So you need a lower retaining wall and it needs to be filled with gravel / crushed concrete for stability to retain the pool remaining level. More than 1 inch off and it needs to be taken down and reset due to the water weight risk of collapse. It will be a never ending project using fill dirt. You might even get 2 weeks in between cycles but it will get old quick.

 

[rckseattle]

Hello Newdude! Thank you for the welcome and the reply. I guess I wasn't to clear on what I am planning. Mostly because I don't have much of a clue myself and am totally making it up as I go. Or maybe you understand exactly what I am trying to do and hoping to spare me from impending doom! So when I said retaining wall I meant a retaining wall around the perimeter of the pool. The pictures don't show any walls yet as I am just trying to get a rough grade cut out first. I will be initially digging about 3-5 inches deeper to allow for a base fill. Once I have the hole and pile close the dirt will be too spread out for me to get the tractors in and out so I wanted to get it close. Next step would be to put up the corner posts making sure its perfectly square. Then finish setting posts and building the walls. At that point the entire enclosure would be compacted, and filled with a couple inches of base and then compacted again and then a top base of sand, all the while checking level and getting as close to perfect as I possibly can.

So will this work? Or are you saying I can't have the pool sitting on fill at all? If that is the case how would I solve this. It has been a huge concern. I have come to learn the weight of water and realize this will all be roughly weighing in at 60 tons or 30 of my Toyota 4Runners! I am so glad I found this forum. I am definitely doing as much research as I can and the weight/fill material has been the cause of most of my nail biting. Not to mention the hours of no actual work getting done just me wondering around my yard muttering to myself (this is how I think) my wife is used to it but I am sure my new neighbors think Rain man has moved in!

Thank you again.

 

[Newdude]

So when I said retaining wall I meant a retaining wall around the perimeter of the pool.

MUCH BETTER !!!!!!! This below appeared it was only for the opening and not the exit.

Then I will add a timber retaining wall all the way around the opening

But. You're on it already.

Or are you saying I can't have the pool sitting on fill at all

Pretty much. It settles too much and needs up to 2 years to do so. You will never get it all the way. Many have tried with 3 inches. Nobody has won. Every last respectable pool install guide says dig down and never add up with dirt. Sooooooooooooooooo many people quit, days into levelling, and took the 'easy way' saying close enough. Every last one of them failed. Lemme call you 3 of our Above Ground pros for their thoughts with several installs each, and MANY MANY watched/helped. @kimkats @Casey @Mdragger88. Ladies, this is R/S. R/S, meet the gals.

Not to mention the hours of no actual work getting done just me wondering around my yard muttering to myself (this is how I think) my wife is used to it but I am sure my new neighbors think Rain man has moved in

Sir. I believe we were twins, somehow seperated at birth.
It was the nurses
Definately the nurses
Had to be the nurses
Yeah, definitely the nurses

 

[ajw22]

To be very clear - A pool must go on undisturbed ground. You can dig down until you create a undisturbed level area that you need.

Placing pool legs on disturbed ground will eventually result in a pool that becomes off level and unsafe.

How to level above ground pool - Further Reading

www.troublefreepool.com

 

[Mdragger88]

You’re better off just digging to level - so the pool sits only on undisturbed ground as suggested & then doing the retaining walls . 1 around the pool where it is cut into the hill & one to prevent the hill it is sitting on from shifting. As stated above it’s ALOT of weight. Fill dirt won’t cut it & it would take alot of crusher run & alot of compacting to fill more than a couple of inches. Even then shifting could occur.
You don’t want an unstable pool unleashing 15k + gallons of water down that hill taking out everything in its path.

I suggest tiers of drainage- 1 at the top of the hill you cut into & 1 around the pool -all diverting water away from the area & your retaining walls to somewhere you want it to go. It’s much easier to do this while you’re already digging & making a mess. Water will always make a way to go where it wants - just think of the Grand Canyon. Better to direct it when possible.

 

[kimkats]

Sing along with me:
Just keep digging, Just keep digging...........

I know it is not the song you wanted to hear but it is better than "Roaring Water Falling on my head"

Undisturbed dirt under the whole of the pool. Now think how neat it will be to set up a "deck" area at the top of the hill to sit on and enjoy the pool!

Kim

 

[rckseattle]

Thank you all for your replies. Even with the bad news I am still so glad I found this site. Ok well that is terrible news but now that are beating it into my head I am beginning to understand and that all makes sense. I was staring out at the hole for quite a while and trying to make sense of it all. Yeah having just the one perimeter wall to separate the surrounding hill from the pool would not cut it would it. That would mean while half the wall is sitting on undisturbed soil the wall on the fill side would be sitting on...well...fill. Ah yes......fill.

Yes there is going to be a last gasp from me and here it goes..

Now having dug around out there for a while I can say pretty emphatically that digging from the very bottom of the hill horizontally is a no go. The soil at the bottom of where I have dug so far is mean mean stuff going deeper is not an option.

What about this...What if I did a STONE paver retaining wall. Instead of the low side of the wall would just being all fill I would tier a system that eventually would end up being about 8' tall I guess. 4' high for the first tier then stepped back 4' then another 4' high tier. The side walls ALSO stone pavers would be stepped up the slope of the yard until I meet up with the cut into the hillside. Drainage trenches all around and the infill for the bottom portion of the wall system SEVERAL lifts of rock/fill/sand/gravel/rock/fill/hope/faith/gravel each being compacted between layers. I would end up with not 3 inches of gravel but several yards of gravel.

Is this something you guys think would work? Or do I sound like an addict trying to rationalize his way out of treatment?

Since digging from the very bottom of the hill is not an option....but I am pretty sure that is not what you mean...you mean to dig to undisturbed soil....the whole hillside is undisturbed soil so as long as the bottom layer of ground is undisturbed soil this could work?

Is anyone on board with this idea? If so, anyone want to split the bill with me? Lol. Yes I am aware this is going to cost a small fortune.

The alternative is telling my wife no pool in which case which one of you has an extra room where I can lay low until all of this bad news blows over? Come on say it with me..."Happy Wife, Happy Life" MAD wife.....Very very very BAD life....send help....please for the love of all humanity!!

This is not looking good.

 

[Newdude]

I know it can be done. It requires an engineer to plan it and certify it. Then you need to follow the (costly) plans to a T, pass inspections and then build the pool.

Start with the engineer. A couple hundred bucks for the consult will let you know if your wife will kick you out for spending more than the house cost, or because you created a mudslide that took out the beloved library downhill.

 

[rckseattle]

Excellent. And knowing how efficient and expensive my building department is the pool should be ready to open ....end of next summer. Alright then, I should start packing.

 

[kimkats]

Okay you are married so you might be able to see in my head what I am trying to say...............see the blue lines? The top line is the slope. The bottom line is where you are going to dig. Notice how you are digging MORE out of the top of the slope? THAT will get you to total undisturbed dirt under the pool. Does that make sense?

 

[Newdude]

The soil at the bottom of where I have dug so far is mean mean stuff going deeper is not an option.

What about a bigger machine ? The ones they let you rent can only do so much. A full size excavator will laugh at the hill (if it can climb it). I don't know what the state of the world did to pricing but it used to be $1k for a day to get a for-hire operator with a machine. Add inflation and things upside down so maybe $3k ? Tell them its for a patio so you can enjoy the yard and you might get a $2500 'levelling'. If you mention a pool, its a $12k 'dig'

 

[Mdragger88]

P.S…..
call before u dig!
Don’t ask how I know

 

[rckseattle]

Well thanks to the pearls of wisdom from @Newdude @kimkats @ajw22 and @Mdragger88 and common sense finally kicking in I decided to "just keep digging" and all I can say is "China is beautiful this time of year!" Ok well I didn't dig that far but I did get to the bottom of this hill. A tip for anyone planning something similar...plan for a LOT of dirt. Imagine an immense pile of dirt and then DOUBLE it. Also, if renting a skid steer....get the ones with tracks NOT tires. If you get the one with tires you will quickly realize why they call it as skid steer because that is all you will do....skid and steer. What you won't be doing is moving any dirt. In fact you will spend most of your time stuck in the mud.

So I am almost ready to move on to step two which will be setting the posts for the retaining wall. So far it is pretty level. I am going to level it better over the next couple days. Then.,....and I would appreciate any available advice on this I am thinking of adding a decent base of gravel and compacting. Is that reasonable? Any suggestions on the type and size? Best practices? Should I top that off with sand or what? Just trying to get the next steps figured out. Stay tuned....

 

[kimkats]

I was thinking about this build and hoping we did not run you off by pushing for the digging it out more. It IS the right thing to do for the future of the pool. I am SO glad to see you came to believe in the need of it being done this way.

As far as the bottom of the pool area that is not one of my strong points. I am going to lean on @ajw22 for that one. I know what my gut says but am not sure enough of it to say it out loud.

LOL on the skid steer part of your post Yeah I can see how that could be a big problem!

 

[ajw22]

If the base soil is solid and undisturbed then just put a pad down under the pool. Don't try and be fancy. I don't think it buys you anything.

I saw a thread recently about someone using pads from Harbor Freight under their pool.

 

[Mdragger88]

I’m sure the pics don’t do the epic nature of this dig justice - I know my pics definitely don’t show the immenseness of the hole lol
I agree w/ @ajw22 - sand or a pad will be plenty - some folks also use those foam insulation sheets but that can get pricey. If you use anything that’s in pieces be sure to tape them together w/ duct tape or gorilla tape. You will need some gravel for the drainage set up around the pool so save your $$ for that. Don’t forget to put down nutgrass killer & insecticide before putting the pool/tarp down.
Keep the pics coming !

 

[rckseattle]

Thank you for the replies everyone, I really do appreciate this site. Well @kimkats I was a little discouraged for a minute but I definitely try to do things the right way and this is clearly the right way. As far as the base and drainage goes I am still a bit unsure. The soil in this hole is kinf of odd there are spots where it is really nice, almost clay-like...some of it just a dirt/sand mixture that is pretty soft and then a good quarter of it is really rocky ugly dirt. One thing I can say is it doesn't drain well at all so I am definitely going to want to make sure I get that dialed in. I also may have dug down a little deeper than I actually needed to so I was kind of planning on adding some base to build it back up a bit so with that being the case @ajw22 do you have any suggestions. Oh and as @Mdragger88 suggested the pictures do NOT begin to tell the story of how much dirt came out of here. My yard is still full of huge piles of dirt and that is AFTER having to find someone to come and haul several truckloads away because I ran out of places to put the dirt! The yard is now nearly full again. Anyway, please let me know if there is anything else I should be keeping in mind or am missing. Again sure appreciate everyone. I will update more later its a rare beautiful spring day here in Seattle so I am going to hang out in my hole!

Robbie

 

[ajw22]

Use 57 stone if you need to build up the base.

Gravel Around Pools - Further Reading

www.troublefreepool.com

 

[Dirrby]

I used the foam pads from harbor freight and absolutely recommend it. 10 dollars per pack gets you 16 sq ft. I didn't tape them together and with one person helping it took less than an hour to put down for a 20 ft round intex. You would think the weight of water wound flatten them out and you wouldn't get much cushion but thats just not the case. Totally worth doing