Cast Iron drain plugged, options

[brian89gp]

This is in a house built in 1890, it is likely that all of this cast iron is original.

I have 3x 4" drain exits out of my bathroom slab that are along the back basement wall about 3' from each other, two have clean-outs and I have pulled them and there is about 1/2" of grease buildup. These two service two bathrooms that are an addition with venting out of the addition roof. The 3rd drain is the main/original main stack going out the attic roof which services the 2nd floor bathroom. I just got done removing all 35' of it today due to it being in horrible shape (running cracks from the basement all the way up through the roof and a few rusted out spots). The buildup in the inside was down to about 1" of open drain for almost the entire run, not even big enough to fit a golf ball down. So...that is why the toilet up there never flushed well at all....

So, what do I do about this 3rd 4" pipe that goes into the basement slab that is pretty much completely plugged? Is it something that a rotor router person or plumber can clean out? The buildup inside the pipe is like a very black grease/dirt combo and it is fairly easy to knock loose. I imagine that these 3x 4" pipes all join up and exit to a single drain at the street?

After seeing the completely plugged pipe and the buildup on the other two I was going to have someone come out and clean them out anyway since the drain pipe runs 45' under the basement and then 20' to the street. Should I even bother with having them try to unplug the really bad pipe? Eventually I will have the pipe under the slab replaced but was hoping to put it off for a while longer.

 

[Jadnashua]

Do you think everything was installed at the same time? If so, then cleaning out that third one is likely to get the snake to go through the weak spot(s) and create a bigger mess. Wait for someone with more experience in this, but it sounds like you probably need to continue with your replacements.

 

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[brian89gp]

I know the basement slab was poured maybe 60 years ago, it is possible that the other two cast iron pipes are newer then the original stack but they would still be 60 years old at least since the concrete is undisturbed. They definitely are in better shape. The main stack had several area's where it was completely rusted out where as these other two are solid.

The two toilets on the other two 4" drains do not have any trouble and there isn't any water backing up at the clean-out plug after I drain a tub of water. Washing machine in the basement doesn't ever back up either. I also have two floor drains (2" pipe) in my paved back yard (city lot) that drain into the sewer line at some point that capture 2000sq/ft of rainwater.

 

[brian89gp]

-Far left in the corner with a white bag over it is the really plugged up line. This was the main stack that went up 35' and through the roof
-The white up-side-down toilet flange is blocking off where a toilet used to be. 4" cast iron, zero buildup inside.
-The 4" cast iron that angles to the left at 45* is for one bathroom unit and has maybe 1/2" of buildup
-The 2" cast iron with the copper pipes leaning up against it is a vent that reenters the main stack above water basin level on the 2nd floor
-The 3" ABS on the far right is the other bathroom unit, it goes into a 4" cast iron hub in the concrete. Minimal buildup in the ABS.

The toilet flange and the original stack in the corner, below the concrete, both go towards the cast iron pipe with white clean-out at a 45* angle away from the wall.

I need to have a plumber come out anyway to snake a shower drain and to put a vent flange back on the roof. Just a matter if I should have them rooter the main lines or not and if it is possible to unplug the plugged one. I will say that the weak spots and rusted out spots were around the cracks, the few sections of non cracked pipe were still very solid.

...The shower drain is plugged due to 10-15 22.5* fittings back to back between the drain and the 3" pipe that is 2' away. Everything else on the 3" pipe drains just fine. I have no idea what they were thinking when they put that one in.