Pipes are leaking, diving in to fix them. (long)

[Aleforge]

First of all hello everyone! I am brand new to this forum and hope I don't exhaust everyone with my drawn out questions.

(WARNING VERY LONG)

A bit of a backstory:
I have an old (2001) in ground fiberglass pool, I am the second owner (4 years) and it's been a nightmare. I had some really bad hydro-static pressure hit it a winter ago (very heavy rains) and it ended up forming a crack in the bottom (about 12 inches). The pool probably should just be removed at this point but I am going to just do what I can to keep it on life support. Plus really I have nothing to lose at this point.

As for the crack I drained it (lol) and did my first fiberglass job. I ended up pumping the ground water around it out prior and luckily it didn't rain! Thankfully I actually did a decent job and it's held since it was refilled.

SO... fast forward to this season. I had a ton of new settling in my yard, it was bad. The city poured new concrete in my giant circle in front of my house and I got another round of street creep. It ended up pushing my ground backward enough that my return / suction pipes near the pump leaned.
https://i.imgur.com/4uMGh6B.jpg

Anyhow I fired up the system and it wouldn't hold prime... (YAY). So I had a leak locating company come out and they found several coupled in the same area. Both return and suction side. Coincidentally the problem area is straight from the pump station. So I am guessing they got a massive amount of pressure on them and cracked.

Here are the leaking pipes areas (white chalk): https://i.imgur.com/ImQ84m4.jpg

The company quoted me 1900 per line repair and couldn't guarantee that was the only issue. They thought each line (4) coupled in that area had leaks so that was a grand total of 7,600 bucks.

I noped out of that idea, it's concrete and PVC... all near the same basic area. I don't mind getting my hands dirty so it's getting cut in about an hour along this area: https://i.imgur.com/tNYfEPV.jpg

(long story apologies)

So I have a few questions, for one I was told that if I remove that concrete my pool is going to pretty much "explode" in that area. Not their exact words but pretty close. I assumed the weight of the water would keep the shell down. And made the assumption that since the dirt still exists behind the wall that it wouldn't fall over. What do you guys think?

Secondly from all of the hydro-static damage I got 2 bulges in the deep end. The pool was back filled with sand (yay), so it seems to have washed downward. I want to fix that, and the only idea I have is to cut the concrete and dig down ward along the wall to relieve the pressure, then back fill with gravel. Thoughts? https://i.imgur.com/976yk7u.jpg

My main concern is the integrity of the shell while so much concrete is removed. I held off on the bulge area and thought maybe it would be best to do in "phase 2".

So ya this hasn't been fun, hopefully I can start digging those pipes out tonight and pressure it up for leaks. I plan on cutting out everything I can find and replace it all in that area.

Comments, input and advice VERY appreciated!

[Teapot]

Been to plenty of trade shows where a fibreglass pool is full of water on the stand with a frame around it so I don't buy explosion. If you are going to have ground movement/creep then i would go for termite resistant pool flex pipe. If ground water is an issue dig a well beside the pool but deeper and fit a sump pump to drain the water. If you have a main drain or two go also for hydrostatic valves sure you'll get dirty water in the pool but it will relieve the pressure build up, seen one of these pop right out of the ground.

[Denniswiseman]

I can confirm the popping out of the ground as it happened to me and was one hell of a job to reinstate

[Aleforge]

Thanks guys! I appreciate the help!

The concrete is now cut and I started to dig around in there. For one thing I can confirm the back fill is pure sand and A LOT of it. I can also say that so far it hasn't caved in, exploded or otherwise. =)

As far as the pipes, I found them fairly quickly, they are in fact flex pipe I suppose that is fairly normal? I was imagining PVC and this fantasy where I would be able to cut out a few leaky sections and viola. But no... I guess nothing comes easy.

https://i.imgur.com/OYMBAgH.jpg

And... well there are cut (from saw and shovel) electrical wires all over (lol). I think they are electrical wires at least, they seem to be coated. You can see them in the picture above. One goes "through" the concrete in one spot. Who knows though, so far I have found large pieces of wood even parts of my wooden deck buried.

There is a neat chain also, I assume it ties in somewhere to help keep the pool from falling inward? It has some slack though and it seems there once was another that broke off (or the guy sawed through it).
https://i.imgur.com/69n2lwY.jpg

OH! And this mysterious hole... it goes down as far as I can see... So odd: https://i.imgur.com/cYzEDca.jpg

Anyhow I am going to dig out all of the pipe and do some pressure testing and cross my fingers that it leaks in that area. The sand / clay is very wet there. But of course they both hold water forever underground.

One scary question... can flex pipe be "patched"? I noticed it running into the T for the jets. Ideally all of it needs replaced obviously, but I am not sure HOW much money I should put into it at this point.

THANKS!

[Denniswiseman]

I can confirm that sand is the correct medium for backfill for a fibre glass pool
When back filling a fibreglass pool you should only back fill up to the water level, rise about a foot and then more backfill. You can also water the sand in to lose any air pockets. The bulge could be where they backfilled to much
Your electrical wires I would be inclined to renew
The chain wouldn't be used to stop the pool falling in as the water holds it out, it may have been used to hold the pool down
My flexible pipe was used with compression fittings, unless there is a problem with it I would leave alone
Also follow Teapots advise and dig a well beside the pool but deeper and fit a sump pump to drain the water. If you have a main drain or two go also for hydrostatic valves

[Aleforge]

Thanks Dennis,

It seems the bulge had the back fill settle behind the bulged area. It sounds hollow up high when you bang on it. I was thinking about removing the decking above it and dig behind the bulge removing some pressure? Good or bad idea? The bulge is ROCK solid. In my mind it would slowly move back into place as the pressure is relieved and then I could re-back fill. My mind is full of "ideas" though that my wife questions.

> dig a well beside the pool but deeper and fit a sump pump to drain the water.

I have a PVC pipe that sticks of the ground about 8 feet or so behind the skimmer? I assumed it went under the pool as I have been using a transfer pump on it to get rid of the water around the shell? Is that what you guys are talking about?

[Denniswiseman]

Thanks Dennis,

It seems the bulge had the back fill settle behind the bulged area. It sounds hollow up high when you bang on it. I was thinking about removing the decking above it and dig behind the bulge removing some pressure? Good or bad idea? The bulge is ROCK solid. In my mind it would slowly move back into place as the pressure is relieved and then I could re-back fill. My mind is full of "ideas" though that my wife questions.

> dig a well beside the pool but deeper and fit a sump pump to drain the water.

I have a PVC pipe that sticks of the ground about 8 feet or so behind the skimmer? I assumed it went under the pool as I have been using a transfer pump on it to get rid of the water around the shell? Is that what you guys are talking about?

If the rest of the pool is satisfactory I would give it ago
How deep does the pipe go (to the bottom ofthe pool) and can you get a sump pump down it
It seems you have idea what to do and aren't afraid to break up concrete
Look at what I had to do when my pool popped out of the ground because of ground water which I didn't expect as it was on a slope and partially out of the ground. We all make silly mistakes sometime, the clever thing is not to do it again