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Thread: Installing on slope - how to handle backfill?

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    Installing on slope - how to handle backfill?

    We have been delayed 5 weeks so far due to rain, but it looks like Friday will FINALLY be our dig day (install on Saturday). Fingers crossed! We purchased this home last summer and had hoped to dig out the pool the previous owners had filled in. Long story short, we can't...it would cost double what a new inground would be, and we didn't have that kind of money in mind. So we've decided to install an above ground, but because of the slope of our yard it will have to be dug out under ground level 24 inches on the side closest to our house. That is where we intend to put a deck.

    Pool installer said that we need to fill the pool, then install a french drain and backfill with dirt. Absolutely do not use gravel because it would damage the pool. Said he's never seen a pool rust if the french drain is done correctly.

    I've searched old threads on the forum and read extensively about others in this same situation, and I've not seen any consensus at all. It seems folks have done many different things, and unfortunately there aren't a lot of '10 years later, here's how that decision fared' posts. SO, I'm looking for input and experience in this area. Anyone with a pool installed into the ground on just one side - what did you do and how has it worked?

    Pics - hard to tell much because this hasn't been installed yet, but here is the site:



    The landscaping against the back of the garage will be removed, and that area plus a couple of feet into the grass will be deck. The pool will be ~30" out of the ground at that spot, as they are digging down to the low point at the back of the hill. The pool is 33' round.

    This will all be deck



    This is the view from the low point, looking back at the house



    This is roughly the back center of the pool-to-be, looking back



    - - - Updated - - -

    I should note that the pool does have resin including bottom track and the instruction manual does address this type of installation, so we at least have that in our favor. I hope.

    We would be routing the french drain over to drain in the woods. There will be a fence fully enclosing the pool so we need to get the drainage done before the guy does the deck/fencing.
    27k gallon 33' round, partially buried 22" Sandman sand filter, 1.5hp 2 speed TidalWave pump, Pentair 'Lil Shark with leaf canister, TF-100 Test Kit

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    JasonLion's Avatar
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    Re: Installing on slope - how to handle backfill?

    You certainly want drainage on the higher ground side of the pool. There are a couple of different ways to do that.

    I prefer to leave a several inch gap between the pool and the dirt, so the pool is not buried, though I've seen it done the other way.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Installing on slope - how to handle backfill?

    If we left a gap, wouldn't the dirt eventually cave/wash over against the pool anyway? The dig is set to be 1 foot larger than the pool all around, so it would be a 12" gap between the pool and the wall of dirt.
    27k gallon 33' round, partially buried 22" Sandman sand filter, 1.5hp 2 speed TidalWave pump, Pentair 'Lil Shark with leaf canister, TF-100 Test Kit

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    Re: Installing on slope - how to handle backfill?

    If we left a gap, wouldn't the dirt eventually cave/wash over against the pool anyway?
    Build a retaining wall.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Installing on slope - how to handle backfill?

    I would not put the new pool over the filled in pool area.

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    Re: Installing on slope - how to handle backfill?

    We aren't, hence the less-than-ideal sloped location of the above ground install. The inground was directly behind the house and that area will remain open grass. We have 3 acres of land, but we are at the top of a hill and most of the land is either hilly or wooded, so we are pretty limited.

    A retaining wall is definitely outside the scope of what we had planned. Are y'all saying that is the only way to go? I'm a firm believer in 'do it once and do it right' so if it's necessary I will, but I'd prefer not to go that route.
    27k gallon 33' round, partially buried 22" Sandman sand filter, 1.5hp 2 speed TidalWave pump, Pentair 'Lil Shark with leaf canister, TF-100 Test Kit

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    Casey's Avatar
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    Re: Installing on slope - how to handle backfill?

    Good luck.
    I'd bet you my bikini you'll never get TFP water from a pool store!

    24' Sharkline Venture De Filter

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    Re: Installing on slope - how to handle backfill?

    haha! That does not sound encouraging! Are we in for trouble?
    27k gallon 33' round, partially buried 22" Sandman sand filter, 1.5hp 2 speed TidalWave pump, Pentair 'Lil Shark with leaf canister, TF-100 Test Kit

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    Re: Installing on slope - how to handle backfill?

    I dug down about 3' on the back side of my pool. Just the winter snow/thaw has washed about 3" of dirt down around the base of my pool.

    I plan to install a deck this year. And the posts of the deck should hold some of the dirt back. I'm going to add supports between them as well. Just for some extra support of the dirt.

    Like Casey said....Good Luck. Her pool is dug back into the hill as well.
    24'x54" 15k AG round - Outback Genesis
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    JasonLion's Avatar
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    Re: Installing on slope - how to handle backfill?

    One of the challenges is that your available range of options is heavily dependent on your exact soil conditions. We aren't in any position to judge the soil conditions, so no idea how the slope will respond to being dug out and how important a retaining wall is, or isn't. Best case you are fine with any approach. Worst case the pool will slide down the slope no matter what you do. The likely cases are all somewhere in the middle, i.e. a little reinforcement would help, but nothing too elaborate. However, it is impossible to say much of anything for sure.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    yostmatt's Avatar
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    Re: Installing on slope - how to handle backfill?

    Mine is dug into a hill as well. The pool walls are 52 inches, and the back of the pool, the grass is around 45". My instructions said to put in perforated pipe around the pool, and backfill with stone. I used 2b limestone. However, the pool I have is also rated for full in-ground installation.
    ~Matt~ Radiant Metric 24'x52" 14k- built into a slope. CircuPool Si-30 SWCG. Jandy 200 SqFt cartridge filter. Pentair Optiflow 2-speed 1HP pump. Wanda the Whale. TF-100 Test Kit. Hard Plumbed.
    My Build w/ lots of pics

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    Casey's Avatar
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    Re: Installing on slope - how to handle backfill?

    Quote Originally Posted by JasonLion View Post
    One of the challenges is that your available range of options is heavily dependent on your exact soil conditions. We aren't in any position to judge the soil conditions, so no idea how the slope will respond to being dug out and how important a retaining wall is, or isn't. Best case you are fine with any approach. Worst case the pool will slide down the slope no matter what you do. The likely cases are all somewhere in the middle, i.e. a little reinforcement would help, but nothing too elaborate. However, it is impossible to say much of anything for sure.
    I watched n studied my hillside and how it reacted to rain, snow and if there was run off water and if so how much, for 3 long years. This will be our 3rd year with The pool and it hasn't gone anywhere. The first year n half was deckless and there was dirt pushed up to the wall,on the back end due to weather. My pool is so far into the hillside that I can see the hillside over the top rail in some pics after install. All I have to say is sometimes, you just need a pool and will do just about anything to get one, within reason. As Jason has said, all this land we share, it reacts differently. We couldn't possibly know if your pool will slide or not, hold water or drain, be clay or black gold (that's good dirt for planting in case you didn't know)... Hope for the best and prepare for the worst case scenario you could ever imagine and prepare the ground to make sure it doesn't happen.
    I'd bet you my bikini you'll never get TFP water from a pool store!

    24' Sharkline Venture De Filter

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    Re: Installing on slope - how to handle backfill?

    Well we have clay soil, I know that for certain. There are other retaining walls on the property that haven't budged in years, so maybe we should delay the deck builder and do that.

    Off to check out your build thread Matt. Thanks!
    27k gallon 33' round, partially buried 22" Sandman sand filter, 1.5hp 2 speed TidalWave pump, Pentair 'Lil Shark with leaf canister, TF-100 Test Kit

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