Sewer Pipes in Concrete Pool Walls?

[altzone]

Hi
Some people (not plumbers) have advised me that it's not such a good idea to
a) Have 4 x 90deg bends in a sewer pipe
and
b) Encase these pipes in the concrete walls of the new pool.

You can see the problem in this video:

and the re-routed pipes here that will be encased in the concrete walls of the pool:

and a video of the rebar work before concreteing is to start next week.

One pipe comes from the main bathroom and the other comes from the kitchen and laundry sinks.

The propery has quite a slope, so there is a lot of fall on the pipe.
And obviously is would have been a massive effort required to reroute the pipes completely outside the pool walls, and this would actually encroach upon an existing sewer easement along the property. So I understand that there needs to be some compromise here.

Any advice appreciated. Like, is this such a horribly bad idea that it's destinited to fail? It seems like a decent compromise to me. And I figure the pipes are safer in the concrete than in the ground?

This is in Sydney and was done by a third party qualified plumber, not the pool people.

Thanks.

 

[oz-plumber]

You would hope that the pipes are lagged in some form.
They will need some movement.

Regs in Victoria state 25mm insulation around sewer pipes encased in concrete.
Australian regulations - so I would think your need the same.

If the pipes can't move a little, the only way to access them due to breakages will be through the pool walls.

I also can't see any access points to get into the sewer when it blocks - and I'm sure it will.

Good luck and get a Certificate of Compliance from the Plumber - before the concrete is poured.
Also, keep his details - you may require them in the future.

Was the job done by a Licensed Plumber - not the pool company.

It's illegal for non licensed people to do underground sewer works and all underground sewer works need to be notified to the relevant authority.

Hopefully - for your sake - opening a can of worms

 

[altzone]

Thanks. Yes the job was done by a licensed plumber. There is a ground access hole only a meter or so at the bottom end beyond where they join.
What does "lagged" mean?
How will there be breakages if it's in the concrete?

 

[altzone]

Actually, having another look at this, the pipes are sitting on a shelf that I think will be outside the wall. But it would need some sort of cover sheet over it before the concrete is sprayed on. I'll ask about this tomorrow.

 

[oz-plumber]

Google Polilag.
This should be wrapped around the pipe to roughly 20mm thick.

Breakages in concrete occur. Something settles - pool or ground around pool. If there is no allowance for movement the pipe will crack or break.

Anyway, its all in the Regs. Non compliant work - Plumber liable ( for as long as they are in Business )
Up to you after that.

We did a repair that costed 30k for a similar type installation that you have in the pics.

If we broke the pool wall - who knows, 100k repair?

 

[oz-plumber]

Whats going to hold the pipe on even grade in that situation?
There are no supports to hold the pipe in place or on grade.

Until this is resolved, I would hold off the pour.
You need a definite resolution to the problems before the pour.

Pool company will say - Plumbing Problem.
Plumber will say - Pool company fault.

Keep videos - you may be the one footing the bills for repairs.

Plus the drain is running a longer distance from the original drain.
I hope the required falls are maintained.

Unless the original drain had a lot more fall than required, then the extra distance of the drain will not be enough to make correct fall.
You're working between 2 fixed points and adding 6 -8 or so metres of drain, which requires an extra 100mm - 150mm fall.

Drain looks fairly flat in some sections.

 

[fowlerboi]

Whats the thinking behind lagging underground drains?

 

[altzone]

Thanks, I'll ask what the plan is tomorrow in regards to the concrete pour. But given the lack of sheeting covering the pipe, I presumed the plan was to encase it in the concrete.
I found this Polilag, are these the regulations in question?

Polilag is made from Expanded Polyethylene ( EPE) Polilag is a closed cell, non-absorbent lagging that complies with Slab and Footings Standard AS2870 Australian Footings Standard AS2870-2011 5.6.4(a) states that ; "Closed-cell polyethylene lagging shall be used around all stormwater and sanitary plumbing drain pipe penetrations through footings. The lagging shall be a minimum of 20mm thick on Class H1/H1-D sites and 40mm on Class H2/H2-D and Class E/E-D sites." Allows pipe movement through concrete as specified in AS3500 Part 2 Clause 3.8.2b

 

[oz-plumber]

Whats the thinking behind lagging underground drains?

The drains will be encased in concrete.
Typically no lagging required underground, except when passing through concrete footings.

Another clause: when encased in concrete.......fully lagged pipe.

Basically, homeowner going to end up footing bills for repairs.
Pool company will say they employed plumber to do alteration to sewer.
Plumber will be liable for defects.. Plumber closes shop.... Homeowner foots bill for repairs.

During process, homeowner has to drain pool and damage pool to access sewer pipe for repairs.
Ends up digging around pool perimeter to relay sewer pipes that are installed incorrectly.
Drain falls can't be met......and so on..

Seen it before.... homeowner pays more for sewer rectifications than cost of pool installation..

 

[ShaunCorbs]

Whats the thinking behind lagging underground drains?

Due to the wait of the pool / concrete above it could settle moving the drains the insulation allows some tolerance / squish for this (I’m guessing )

 

[altzone]

Another question.
Assuming the fall is fine, and putting the concrete issue aside, are these 4 extra bends likely to lead to blockages?
And if so, is it possible (easy) to unblock them from a vertical ground level access hole about 1m behind where they join?
Thanks.

 

[oz-plumber]

Bends always contribute to issues.
I'm not bothered about the extra bends.

Getting access to the drain is critical.. water jetters can get to anywhere for a point relatively easily.

A cracked or broken drain will be the issue

Are you a developer or homer owner?

 

[fowlerboi]

Ah OK

I've not seen footings poured round drains. I think the typical way here would be to pour the footing lower build up around it and lintel it. Using pea beach to support the underside of the drain work for movement

 

[altzone]

Bends always contribute to issues.
I'm not bothered about the extra bends.

Getting access to the drain is critical.. water jetters can get to anywhere for a point relatively easily.

A cracked or broken drain will be the issue

Are you a developer or homer owner?

Thanks. That's a relief. Pipes seem to be working fine so far anyway, no issues.
I think I might be wrong about the concrete, will confirm tomorrow. Seems silly that they would actually encase in the concrete walls actually. I'll report back.
Home owner.

 

[altzone]

Talked to the pool guy this morning who confirmed it is being encased in the concrete, and it's the best and safest option under the circumstances. It has been decided upon and certified by the licensed plumber as the best option, and that you have to be on site to inspect to know what is the best solution here under the circumstances. The compact clay we have means movement won't be an issue.
No insulation tape is used because it's not a house footing, and that this is standard practice in mains sewers, and that's how our main sewer was also replaced in our backyard right next to this, it's simply encased in the concrete. I looked at some old photos and I think he's right.

He said the pipe is safer in the concrete than loosely compacted and back filled under the ground outside the concrete wall. Again, I think he's right.

Also, the plumber said there was plenty of fall and that the water was in fact "racing" along. So no issue there.

The thing is we don't really have another viable option here. To dig out a massive trench to the depth required a distance from the pool is a massive and very expesive operation. Not to mention there is a existing mains sewer easement right next to it (certified ok for distance BTW).

So seems like this has to go ahead as-is.

 

[altzone]

We are going to add an extra inspection hole on the top side of the pool, so we'll have one top and one bottom. This should help with any blockage issues either end.

 

[oz-plumber]

You're kidding yourself.
Pool guy said to encase pipe in concrete was best practice?
Plumber said no insulation required because pipe was not penetrating footing?

Generally when you lay a drain you surround the drain with screenings.
When you lay a drain in concrete, you wrap the pipe with lagging to allow for minor movement, as you do when penetrating a slab or footings.

But then again, it's you pool and your plumbing.

I can't be bothered finding the exact regulation, but it's something like 25mm insulation around sewer pipes encased in concrete.

Don't worry, by the time you have problems, you would have paid the pool guy and the plumber.

Plumber doesn't sound like he knows the Regs.
Pool guy will blame the Plumber - and be liability free.

Good Luck.

And I like the way you state: ' I think he's right '