PVC pipe in concrete

[Taylor]

I think this is okay to do, but asking just in case.....

Recently had plumbers remove a CI pipe from under a load-bearing support (no footing) in basement.....I could never have done what they did, and I'm still having difficulty sleeping thinking about it.....I am thinking of filling in the removed material with concrete. I figure I should wrap the PVC that replaced the CI with sill seal to give it room to expand, and also allow replacement later if necessary. Is there anything wrong with this?

The support sits on a plate, but there is evidence of structural failure in the past so I am not complacent.....

 

[Redwood]

Is this the one in question?

 

[Sponsor]

 

[Taylor]

Yes. That plate (top of picture) is now sitting on air.

I freely admit, I could never be a plumber. I don't have the nerves for it.

 

[Redwood]

Put dirt back in the hole.
Wet it until a puddle forms.
Use a broom handle to poke into the dirt allowing the water to all disappear.
Add more water creating a puddle.
Repeat the probing.
Do this repeatedly until the puddle isn't going down.
Wait 24 hours.
The pipe should be covered with dirt.
Pour concrete.
Done!

 

[Taylor]

Sand better than dirt?

This is the procedure I was planning for the whole trench (and the dug-up laundry room).

But I have to wait for inspection first....

Would concrete under that plate be a waste of time, or downright harmful?

According to my engineer, he doesn't know what's holding up that plate. I haven't told him about recent developments.

 

[Redwood]

Use whatever material is required by your local code.
Use the compaction procedure I gave above.
I would put a sheet of plastic between the wood and the concrete.
You can tell your engineer not a helluva lot!

 

[Taylor]

I would put a sheet of plastic between the wood and the concrete.

I've already injected the plate with wood epoxy as a retrofit treatment to prevent rot, but I'll also follow your tip, thanks.

 

[hj]

plate

That plate is being supported by both sides of the concrete slab. There is little, if any, pressure on it because of the way the wall is constructed. Just pour your floor slab and forget about it.

 

[Taylor]

Last questions

I am about to leave on a (much-needed) vacation. Before I leave, I plan to have the debris hauled away, so my neighbors don't dump it in my window while I'm gone.

Should I plan to keep the soil I've dug out, and plan to cover the entire pipe with it? I've also got large chunks of my laundry room dug up, some of it for footers but also just a lot excavated for rerouted pipes.

I used sand under the pipes, hand-tamped, and I don't think the hand-tamping has done much. Right now I'm planning a regime of repeatedly wetting and adding sand under the pipe until it appears to have a solid base. On top of that, sand or soil? Suggestion here appears to be soil (with wetting until it's settled), but just checking.

I also have some pipe high ends resting on gravel (above French drains). Is that okay?

In the trench I dug out, the original plumbers had filled the trench with all kinds of debris (bricks etc). Although I have lots of similar debris, is it a bad idea to fill in a trench with PVC pipe with it, at least close to the pipe?

Forgot to ask the BI during inspection yesterday, and he's hard to get ahold of.

Thanks for any help.

[Sorry for out-of-focus pix, don't have a flash for my camera.]

 

[Taylor]

CI stack on PVC main drain

I know e.g. Grumpy has in the past said it's a bad idea (and violation of MA code) to put PVC pipe under a CI stack. FWIW my main drain under the stack had settled into a horizontal position, no doubt at least partly due to the weight of the stack on it. The pipes were almost completely blocked up.

I am not relying on the PVC for support. I have 3 riser clamps and plan to wrap plumber's tape around some of the hubs too. I am relying on the framing to support the stack.