Need input on weird plumbing problem

[Jim Oaks]

I'm working on the bathroom in my daughters house. It's on a concrete slab. Pulled up the linoleum, started scraping up the glue, and found a bad section of concrete along the wall that was starting to crumble.

I ended up pulling small chunks of concrete out and making a hole that goes under the wall. Reaching in there, I found a white PVC pipe that runs down through the wall, and in to the ground. I also discovered that the bottom of this pipe is completely open. I think there's a connection between this crumbling concrete that goes under the wall, and the PVC pipe I found. The ground / concrete isn't wet down in the hole.

I want to clean out all of the loose concrete, and pour new concrete in the hole, but I'm really puzzled by this open PVC pipe. There is an upstairs bathroom above this one. At first I thought it was the drain pipe from the upstairs, until I found out that it's open on the bottom.

Can any plumbers / contractors explain to me why this pipe is running down through the wall, in to the ground, and is open on the bottom??

 

[kimcrwbr1]

What size pipe is it? The only white pvc i can think ov is it is for a condensate drain for a ac coil or a drip pan for a water heater or washing machine? If it is for any one youto want to route the drain outside the house not under the slab.

 

[kimcrwbr1]

Another possibility would be a condensate drain for a high effeciency furnace that would explain it being dry in the summer and the high acid content of the water will break down the concrete.

 

[rusty ol ranger]

Im by no means a plumber.....but it isnt a stink pipe for the shitter/sewer line is it? Some older houses have those but they usually vent up top.

 

[Curious Hound]

That is a weird one. How big is it? You might want to dig a little bit further to see if there is another open pipe that it should be connected to. Otherwise, if it were me, I would connect onto it and route it outside where it can be watched for a while. Avent line should go up, not down. A condensate drain will generally be 3/4" or 1/2" pipe. Other drains are generally bigger.

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[alwaysFlOoReD]

Was there an option for central vacuum? Lots of houses up here are plumbed for central vac using ~1.5" white pipe. Tho I can't see why the pipe would end like you describe.

 

[Jim Oaks]

I haven't dug that much out. I don't want to dig to much out from under the wall. I'm guessing its a 3 or 4 inch pipe. There's no way for me to run it anywhere without tearing up a lot of flooring and concrete. I'm thinking about remove some of the loose pieces and filling it back in with Quickrete.

 

[saskbill]

No chance this is someone's do-it-yourself Radon venting?

https://airthings.com/us/diy-radon-mitigation-guide/

 

[saskbill]

Or maybe something to do with weeping tile? (Not sure why something would drain out to the weeping tile but...

 

[Jim Oaks]

The Radon vent is the only thing that could seem close since it ends in a sandy soil substance, although it doesn't seem as if it was done properly. I found some black plastic sheeting in there that I'm guess is a vapor barrier under the concrete??

I've wondered if the pipe runs out of the roof and is open on top allowing rain water in. Maybe it allows moisture to enter and the moisture is causing the concrete to crumble.

 

[Curious Hound]

I didn't know they did radon vents for slab homes. But I guess that's a possibility. This could be something code related that is peculiar to certain geographical areas. Those of us in other parts of the country may not know about it. You could call the local building inspectors office this week. They might be able to answer your questions with a quick phone call.

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[Jim Oaks]

Any suggestions about filling the hole back in? The hole goes under the concrete, but I don't want to start breaking it up. I'd like to just poor some in and let it fill in the voids.

 

[chewy012]

Any suggestions about filling the hole back in? The hole goes under the concrete, but I don't want to start breaking it up. I'd like to just poor some in and let it fill in the voids.

Might be able to put some in a hefty black bag, cut the corner off, and squeeze it in like cake icing?

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[chewy012]

Might be able to put some in a hefty black bag, cut the corner off, and squeeze it in like cake icing?

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Might only be able to do small amounts at a time though. Then put something like a running generator near it, causing vibration, letting the 'crete mix to work its way into the nooks and crannies

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[kimcrwbr1]

Spray some foam up in the voids and after a day cover it with mortar. If you use the flammable foam make sure any pilot lights close by are not lit until it gasses off.