Sand washed out

[Nubs101]

Hey all,
Question for you guys in regards to my semi above ground pool and the base sand washing out. The area is about two feet long and maybe 6 inches wide. The way they installed my pool to fit with the slope of my yard one side is about 2.5 feet in the ground and the low end they had to build up 7 inches to keep everything level. I ended up back filling the low end but unfortunately we have had about 6 days of heavy storms that’s caused this to wash away. I’m wondering what my options are and if this is something that’s damaging my liner causing it to stretch. Do I need to drain and repair ? Can it last until it’s time for a loner replacement ? Unfortunately it’s a brand new pool so that may be a little bit. Anyway thank you for your time.

I spoke to the pool company and they recommended I get in the pool and while the sand was wet still to smooth it all out and not to worry too much about the liner. Does that sound like a good option ?

 

[Nubs101]

Here are two more images to help show what’s going on.

 

[kellyfair]

These were professional installers? I’m in disbelief that they built up your low end. And with sand? Nothing to keep it from washing away?

Others will be along to chime in, but I don’t see anyway to rectify this without taking the pool down, leveling properly which means digging down to solid ground, then reinstalling,

If they had to dig into your slope anyway, why didn’t they level down to the lowest spot? Can you show us a photo of the slope?

 

[Nubs101]

I can provide a little bit of backstory that maybe will make a little more sense underneath the sand is 1 inch minus gravel that’s packed. The reason they built it up is as they were digging out the area there was a sewer line that runs through the pool location. They built up base level with the pipe reason for the base.

 

[AK-]

Not suggesting a solution, but sometimes ideas come out of what other people did…

I have my AGP installed with some unusual conditions that I would need some filling. I knew filling with dirty/sand wouldn’t cut because those can settle and wash away. My pool allowed a hard bottom made of mortar (well the manual said 6 parts sand and 1 part Portland cement, so mortar) and that is what I did, my bottom rails are sitting on mortar pad.

 

[zea3]

You can't get in there and smooth out the sand base when there is no sand beneath the pool to smooth. Did they see your photos before they made this recommendation? Your liner is going to be over stretched in this area and it is not going to snap back. Your pool in its current condition is not safe and it needs to be drained, taken down, and re-installed. Anyone who puts their full body weight anywhere close to the washout area is going to put their foot through your liner and displace even more sand. Before long the seam on that liner will fail if it is not supported. Is the seller also the installer?

I can see where the water flow washed out the dirt under the pool, but your photos don't show the entrance point where the water is running under in the first place. Where is water getting under the pool? Also where did that big, jagged rock come from? Was in covered over by sand?

You stated they dug down 2.5" to level and then had to build up the pad 7" when they encountered your sewer line. They did this with sand and a 1" layer of gravel. The materials they used do not compact down to form a solid base. You cannot build up a foundation with sand as it will not compact into a solid, stable base. They should have used 1" lifts of crusher or decomposed granite and compacted between each lift. The gravel they used is too large to compact and hold a shape. Its basically just a bunch of rocks. The purpose of sand in above ground pool construction is to dress the foundation so it is smooth and provide a little padding under foot. It is not meant to be the foundation at all. Once the sewer line was discovered, work should have stopped and a discussion should have taken place between owner, installer, and seller to address where else the pool could be located in the yard or if downsizing the pool is the only viable option.

I'm going to ask a couple of others to give their opinion. @Casey @JamesW @jimmythegreek

 

[Nubs101]

Thank you everyone for the replies. I’m going to try and clarify everything and answer some of the questions. The seller and installer are two different businesses. The seller who handles all the warranty work did not ask nor see pictures so it looks like contacting them again is in order.

sorry for the picture of the rock that was just moved and is a nonissue. They dug down about 2.5 ft. They used approximately 7 inches of 1inch minus and a inch of sand on top. They did this to just cover the pipe and build on top of it. They then back filled the low side with fill dirt. It is being washed out due to heavy rains flowing from the skimmer basket and what I assume splashing in that area.

 

[zea3]

Ok, that helps some. I was afraid you had a larger void under the pool getting ready to open up. However it does not change the fact that the site was not prepared correctly. You cannot build up a pool site with dirt, sand, and rocks. A pool has to be placed on level, undisturbed ground. When that is not possible there needs to be some kind of containment structure such as a retaining wall or wooden box where a level foundation can be made with layers of crusher or decomposed granite.

For now you can try and shove some sand back under there but you must be very careful not to rupture the liner. This will be a short term fix only.

 

[Casey]

This pool build is a mess and it needs to come down. The fact that it's built on top of a sewer line is a terrible idea! That pool weighs THOUSANDS of lbs. Top that off with that liner possibly rupturing in the near future... I'll just say this... I hope you're up to date on your home owners insurance because any in or near this pool could be seriously hurt or killed, and I'll also note that property damage is going to be astronomical given the sad state of affairs were currently going through with the prices of everything.

Take that pool down. That's what I'd tell you. Its unstable.

 

[Casey]

You see this neighbor's house? You're going to repair it when that pool blows out.

 

[Nubs101]

I just want to thank everyone for their opinions. I know context gets lost through text and understand some people may be aggravated at this pool build. I just want to say that obviously this was a hired out job and I came to this board to be educated on this matter. If this is a real safety concern then I will start draining the pool if it can’t be fixed.

I will contact the seller as all the work is warranted through them and update with their response.

 

[Nubs101]

Spoke to the installer who is going to come back out, pull the liner, and replace the sand. They didn’t really comment much on the base and said as long as I properly backfill it nothing will move. They also suggested adding a drainage tile to pull water away from the area. So not all warm and fuzzy feelings there. My only other question would be if I built a retaining wall to secure all the soil in the area if that would be a viable solution?
Thank you everyone for your help. I really do appreciate it as I’m trying to right what’s not been so great.

 

[Selenap]

I’d consider just putting in a drainage pipe and back filling the hole. As for imminent doom, you’re ok. The liner isn’t going to blow out. You have a very minor trench. Unfortunately you have to live with it as a dirt catcher or drain and fix. You do need to address how that water got under there. Back when I put my pool in, we had to dig 4 feet into a hill. We didn’t put in any drainage or a retaining wall and eventually the sand under the coving washed out. All the way around. The plan was to back fill. Never did and the hill has since eroded into a gentle slope to the back side of the pool. The liner lived this way for five years until I got a new one and fixed everything. The ground is stable now the the pool base is surrounded with hard pack clay. The rain mostly just washes over the top of the dirt and out the front. Still need to put in drain pipe and back fill. Point is, you’re not fixing to collapse.

 

[kellyfair]

Spoke to the installer who is going to come back out, pull the liner, and replace the sand. They didn’t really comment much on the base and said as long as I properly backfill it nothing will move. They also suggested adding a drainage tile to pull water away from the area. So not all warm and fuzzy feelings there. My only other question would be if I built a retaining wall to secure all the soil in the area if that would be a viable solution?
Thank you everyone for your help. I really do appreciate it as I’m trying to right what’s not been so great.

My best advice is to recommend you not follow their advice. Definitely take the pool down, but don’t reinstall over another built up area on top of a sewer line.

 

[kellyfair]

I’d consider just putting in a drainage pipe and back filling the hole. As for imminent doom, you’re ok. The liner isn’t going to blow out. You have a very minor trench. Unfortunately you have to live with it as a dirt catcher or drain and fix. You do need to address how that water got under there. Back when I put my pool in, we had to dig 4 feet into a hill. We didn’t put in any drainage or a retaining wall and eventually the sand under the coving washed out. All the way around. The plan was to back fill. Never did and the hill has since eroded into a gentle slope to the back side of the pool. The liner lived this way for five years until I got a new one and fixed everything. The ground is stable now the the pool base is surrounded with hard pack clay. The rain mostly just washes over the top of the dirt and out the front. Still need to put in drain pipe and back fill. Point is, you’re not fixing to collapse.

I’m sorry, I know you are trying to help, but this is not good advice. You are lucky you haven’t experienced more problems.

 

[Nubs101]

Sorry one thing I forgot to add. I called my city a few weeks back in regards to that pipe we built over and turns out it was an extra pipe the builder threw and buried into the yard. Got lucky on that one so that’s at least one hurdle avoided.

@kellyfair

 

[kellyfair]

So the sewer pipe is just a throwaway?

 

[Nubs101]

Correct. Unfortunately didn’t know that at the time of the build because only about 2 ft was exposed on the edge of the pool. I did a poor job of explaining this portion I apologize. It doesn’t run through the center and only about two ft is exposed on the edge of the pool. The options were to build up or did out the pipe to see where it goes. Obviously you know what the choice was made.

@kellyfair

 

[Selenap]

I’m sorry, I know you are trying to help, but this is not good advice. You are lucky you haven’t experienced more problems.

The only advice I gave is finding the problem, and putting in drainage and backfilling. Putting up a wall is fine but all it does is prevent erosion, it does nothing about the rain runoff in the space between the wall and pool. Unless they are getting a significant more amount of rain, that pool is stable. As for my pool, the three inches of evenly distributed stretch at the coving affected nothing but cleaning. Once the dirt settled around the pool, nothing shifted underneath. Sorry I’m not all gloom and doom enough.

 

[kellyfair]

The only advice I gave is finding the problem, and putting in drainage and backfilling. Putting up a wall is fine but all it does is prevent erosion, it does nothing about the rain runoff in the space between the wall and pool. Unless they are getting a significant more amount of rain, that pool is stable. As for my pool, the three inches of evenly distributed stretch at the coving affected nothing but cleaning. Once the dirt settled around the pool, nothing shifted underneath. Sorry I’m not all gloom and doom enough.

Advice to supply adequate drainage is good. Advice that there won’t be any further issues because you didn’t have any further issues, not so much.

I know you’d feel awful if based on your assurances that her pool is now stable, she didn’t make sure it was structurally sound, and suffered a pool failure.

We aren’t competing here. i am always going to err on the side of safety, and from OP’s description, the pool isn’t stable or safe.