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Hello, people who know much more about this topic than I...
We're building a rear extension to our end-of-terrace house, which required moving a public sewer and manhole; in the process we uncovered the old iron water main that feeds our house and the three others in our row. Photo: https://drive.google.com/file/d/10XTLYyj2QsW0L7Li5cBGIlxH5aQCdz1_/view?usp=sharing - the supply direction is from top left, the T is our supply, then it wraps around to run under the rear gardens.
That main is in poor shape; the branch to our house was so bad that my plumber has replaced it with alkathene. However, he tells me it's not possible to safely cut/thread/join on to this kind of pipe in this state, so we can only connect at existing joints. (He thinks the torque from trying to thread it would just split the pipe.)
Unfortunately there's almost certainly no joint between the elbow in the middle right of the photo, and 6m downstream of that, which is under my neighbour's conservatory floor. Rerouting all the way around the extension and conservatory is not an option since said neighbour has fancy patio over most of the area the trench would need to run through.
So it seems I have to re-bury the old main under my new extension - that prospect thrills me, let me tell you. (Although really even if we could find or create a joint under the floor, that wouldn't be much more comforting; the new foundation will touch the existing footings of the conservatory, so there's no gap in between where a joint could be relatively easily accessed.)
I'm probably going to switch from a slab floor to block and beam to make it easier to get back down there if there's a leak in future, but I also want to do everything possible to preserve and protect the old pipe.
We've already had two pinhole leaks in the process of digging this out, which were fixed by my builder using steel epoxy putty (clamped in place with a bit of old lino and jubilee clips to hold it til it fully cures). That solution seems to be holding OK for now.
What would you recommend in terms of protecting the pipe long-term?
My best guess is: expose the whole thing, clean it gently, identify any leaks and patch with steel epoxy, then enclose the whole length inside a 4" or 6" plastic pipe full of pea shingle so any future leakage (hopefully) drains away from the surface of the metal to slow further corrosion. That may be wholly daft though, I'm a biologist not a civil engineer...!
Cheers,
--
Ben
We're building a rear extension to our end-of-terrace house, which required moving a public sewer and manhole; in the process we uncovered the old iron water main that feeds our house and the three others in our row. Photo: https://drive.google.com/file/d/10XTLYyj2QsW0L7Li5cBGIlxH5aQCdz1_/view?usp=sharing - the supply direction is from top left, the T is our supply, then it wraps around to run under the rear gardens.
That main is in poor shape; the branch to our house was so bad that my plumber has replaced it with alkathene. However, he tells me it's not possible to safely cut/thread/join on to this kind of pipe in this state, so we can only connect at existing joints. (He thinks the torque from trying to thread it would just split the pipe.)
Unfortunately there's almost certainly no joint between the elbow in the middle right of the photo, and 6m downstream of that, which is under my neighbour's conservatory floor. Rerouting all the way around the extension and conservatory is not an option since said neighbour has fancy patio over most of the area the trench would need to run through.
So it seems I have to re-bury the old main under my new extension - that prospect thrills me, let me tell you. (Although really even if we could find or create a joint under the floor, that wouldn't be much more comforting; the new foundation will touch the existing footings of the conservatory, so there's no gap in between where a joint could be relatively easily accessed.)
I'm probably going to switch from a slab floor to block and beam to make it easier to get back down there if there's a leak in future, but I also want to do everything possible to preserve and protect the old pipe.
We've already had two pinhole leaks in the process of digging this out, which were fixed by my builder using steel epoxy putty (clamped in place with a bit of old lino and jubilee clips to hold it til it fully cures). That solution seems to be holding OK for now.
What would you recommend in terms of protecting the pipe long-term?
My best guess is: expose the whole thing, clean it gently, identify any leaks and patch with steel epoxy, then enclose the whole length inside a 4" or 6" plastic pipe full of pea shingle so any future leakage (hopefully) drains away from the surface of the metal to slow further corrosion. That may be wholly daft though, I'm a biologist not a civil engineer...!
Cheers,
--
Ben