View Full Version : Please advise on auxillary waste drain.

11-15-2008, 11:01 PM
Hey guys, new to this forum, I searched but couldn't find the answer I was looking for.

Here's the deal: In the process of trenching in drain pipe to carry away the roof water from the 95 yr old craftsman house I bought last spring, I damaged some clay tile pipe running away from the house - doh. I knew the main sewer exited the other side of the house where that line ran, but it turns out there is a second line that takes the kitchen sink drain, and since it was remodeled by the P.O., the dishwasher and laundry as well and this is what I ran into. OK so the drain exits the foundation (below the slab I'm pretty sure) in 2" cast iron and and I figured I'd dig up the clay tile til I got to a nice clean piece and then I'd splice in a some PVC between the CI and clay pipe. I rented a snap cutter and went at the CI and unfortunately it wouldn't snap. I took it off and cut away at the groove created by the cutter with my sawzall and when I got the pipe cut, I saw that the bottom was pushed up with a crack in the middle the runs back up the pipe for at least 8 inches and probably more. The pipe goes into a cleanout in the basement floor just inside the foundation wall directly below the kitchen sink. Above this it is galvi and there is a Studor mini vent hidden in the stud wall.

In an ideal world I would replace this pipe, but I'd want to hire a plumber for this and we're broke. Also the basement is finished and getting at the pipe from the inside would involve demo'ing some tile, finished wall, trim etc. At that point I'd want to replace the galvanized run that goes up to kitchen sink and lower the sink drain since it was left too high by the remodelers and isn't properly set up to drain the garbage disposal etc.

I was thinking of just patching the line outside of the house, I think I can get a clean cut on the CI if I'm careful using my sawzall and splice to 2" PVC. Which will then run about 15' to tie into the clay pipe. Don't ask me about that connection it's a whole other story.

Here are my questions:

- I know the pipe will leak a little from the crack but it's not pressurized and it would all be outside of the house, so maybe not a big deal for a little while?

- When I end up replacing it, will I be sticking with 2"? If so then I could tie into my repair, so all that effort would not be wasted.

- How would I go about removing the CI entirely? I can easily excavate under the footing in that area.

- Ballpark for a plumber to remove it and the galvi running up to kitchen, replace with PVC and replumb the kitchen sink and garbage disposal properly? I could demo the wall and build back.

Lotsa questions I know. Thanks in advance.


11-15-2008, 11:34 PM
Get the cast iron pipe back to where you can make a good cut. Use a carbide grit or, diamond blade to ensure not breaking the pipe further back.

The snapper will often crush old cast iron. The clay will cut fine with a snapper if you have to cut that.

11-16-2008, 12:03 AM
Thanksfor the response Redwood. I do have a diamond grit sawzall blade. Would this line ideally be upsized to 3"? A plumber told me that with the age and size of the pipes we should be cautious with our garbage disposal. But does that mean people use 3" pipe under the kitchen sink?

11-16-2008, 08:42 AM
I would not upsize the line as with the larger line you lose the scouring power of the flow of water. With a disposer some of the toughest clogs I have had to snake were on 3" drains. Big Time Sludge!

11-16-2008, 09:02 AM
Thanks Redwood. After I little more research I figured 2" will be just fine. It takes a kit sink w/disposal and dishwater on first floor and then clothes washer in basement. I'm thinking 2" is adequate (unless someone can tell me otherwise) so I'm going to go ahead with my repair so my house will be functional again, and perhaps next summer I'll replace the last 16" of CI left through the slab into the house. It's only 8" under the surface in this area so I re-ecavating won't be a big deal. I can tie it into the repair I do today so my effort is not wasted. I figure if it leaks a little in the meantime it can't do much harm where it's located, and the soil around it is pretty heavy clay, compacted under the footing so the vast majority of the water will stay in the pipe and run out the new PVC to the sewer.

11-16-2008, 09:23 AM
After the washer under many codes the line should be upsized to 3"

How is the washer standpipe vented?

11-16-2008, 10:03 AM
The washer is vented through a Studor minivent that is hidden in the studwall next to the foundation.

However I just discovered I made an amateur mistake of assuming the CI is 2". It's fairly corroded inside and out so it's a little hard to measure accurately, but I looks to be about 2" O.D. The I.D. is more like 1.5" so I'm going to have to replace it since I need to anyways and I definately want at least a 2" line here. I'm bringing in the professional at this point. Ah the joy of old houses and their funky specs.

- Colin