Under the basement slab- what are these pipes? Looks like 1.5” black pipe covered in clay pipe

[Tudorrenovator]

We are replacing all the 4” cast iron under the slab, and ran into these pipes which aren’t listed in the original blueprints. What are they? Water? Gas?

https://imgur.com/a/ayzn0p9

 

[Tuttles Revenge]

The pipe within a pipe looks odd. Were those clay tile pipes? Were they pipe joined with a hub or were they laid next to each other and loose? Clay or concrete pipes are not allowed under slabs within the footprint of a building (old buildings may have used them as groundwater drainage, but not connected to sanitary/septic) Maybe they used the old drainage pipes as a conduit for a pumped sump drain?

The small diameter blue lines look like domestic water lines. Maybe daisy chained to get water to individual locations under the slab (most cost effective way to install but troublesome to remodel)

 

[Sponsor]

 

[Tudorrenovator]

The pipe within a pipe looks odd. Were those clay tile pipes? Were they pipe joined with a hub or were they laid next to each other and loose? Clay or concrete pipes are not allowed under slabs within the footprint of a building (old buildings may have used them as groundwater drainage, but not connected to sanitary/septic) Maybe they used the old drainage pipes as a conduit for a pumped sump drain?

The small diameter blue lines look like domestic water lines. Maybe daisy chained to get water to individual locations under the slab (most cost effective way to install but troublesome to remodel)

Sorry the blue lines are pex, those are being used for the wet saw. Just trying to figure out the terra-cotta pipe with the black pipe inside.

 

[Tuttles Revenge]

OK.. when we find terracotta pipe under slab its from the 1920s. Its always just laid down with felt paper over the top of the "joints" to prevent silt infiltrating. Its never connected to sewer or septic, just to move ground water from under the slab.

My best guess is the plastic pipe was shoved through it from a sump pump. just a guess.

 

[Jeff H Young]

Sounds like a good theory to me Tuttles came up with homeowner should know where sump pump is if it has one

 

[Eman85]

This reminds me of 50 years ago when I was working at a shop and they were doing some improvements. Breaking concrete they discovered a pipe. Contractor had the idea of drilling into the pipe to see what it was. This is pre cordless drill days so he used an electric drill and drilled into a water pipe. Lucky for him all he got was wet, he could have killed us if it was gas.