Recent video inspection revealed that my 40 year old cast iron pipe under the concrete slab is deteriated to the point of needing total replacement. Some spots the bottom has reduced to nothing, some spots the corrosion build up looks like the inside of a cave...two independent video inspections recommend total line replacement.
I have not yet done the finished flooring in the house, so I guess it's good news I found out now.
In order to replace the entire underground line, I can find a way to determine exactly where it is (no, no records in the city I checked already), and cut up the slab and hope for the best. Or I can just ignore where the existing line is and just design a new route.
It seems designing a new route but tying in existing bathroom group has the advantage of not having to pinpoint exact locations of the line but only specific locations where the existing bath groups tie in. And since I am doing remodeling, 3 of the 4 baths I know where they tie in and I have not backfill with concrete yet.
Doing a new line has the advantage of avoiding cutting a trench across existing walls, I can possibly cut a line along a hallway in a straight shot, but run the risk of running into other pipes below grade that may be in the way (pool pump lines, supply lines, deck drain lines, roof drain lines).
What is the ramification to the structure of the slab is it's a 90'x90' slab and I cut a 90' lone trench across it?
Is there any sense in not making a single 90' cut, but say 8 10' cuts with several 2' sections uncut and I try to bridge under it will that "hurt" the structure any less?
I am laying in new 4" PVC pipe so the trench would be around 6" wide only except where I am doing tie ins.
Thanks in advance,
MC