Removing waste pipe from foundation wall

[patrick0042]

My home's cast iron 4" gravity waste pipe fractured comletely off at interior edge of 15" thick foundation wall. A second complete fracture exists 9" outside foundation. Pipe is strongly bonded to foundation concrete, and the concrete is over 50 years old. Is it acceptable to descale interior of pipe and retrofit by running 3.5" PVC through existing hole and using reducers at each end to unite remaining waste pipe?? Otherwise, is core drilling the only way to remove pipe/enlarge hole to fit 4" piping to match? -- Desperate for solutions. thanks!

 

[Jadnashua]

Hammer and chisel? If the pipe is 4" elsewhere, you can't throttle it down to go through the wall.

 

[Sponsor]

 

[Gary Swart]

If I read your question correctly, you want to go for 3" PVC (no such thing as 3.5") to 4" cast iron then back to 3" PVC. If that's what you are suggesting, the answer is no. You can not decrease the size of a drain. If it was my job, I'd use a rotary hammer/drill with a long 1/2" bit and drill around the CI from both sides, removing as much material as possible. Then a good sledge hammer on the end(s) of the CI should break it out.

 

[patrick0042]

Thank you, Gary and Jim

That's what I was afraid of...not OK to reduce a waste pipe. Time to earn some of that sweat equity!

 

[patrick0042]

Took your recommendations to stick with 4" piping. Rather than chisel, rented ($70) a chipping hammer which melted the concrete like butter, easily loosening the existing cast iron and also allowing me to slightly enlarge the hole so that I can pass the thicker walled 4" PVC through. Worked like a charm, now will add a backflow preventor outside the wall. Thanks again!