Disappearing water pipe...

[marktheherald]

Hi, first post for me. Our bungalow was built in 1959 and the general area is heavy clay. Whilst there has been some slight movements evident over the years (all seems fine now), my query concerns the storm water system. The down pipe that serves the rear of this semi-detached property goes directly into and under the concrete side driveway. This downpipe was asbestos and completely clogged, I have installed new plastic piping and linked it to the buried clay pipe work. This clay system runs away at about 15 degrees under another concrete slab which has dropped by about 1". I have now broken back this slab and exposed the clay pipe for about 5ft at which point there is a 90 degree clay bend straight down. The run of straight pipe seems to have subsided in the clay (no fill around it), and broken downwards out of the bend socket, so all water going into clay! I can easily replace the run of clay pipe to the clay elbow. It's just that I do not know where the storm water goes. Running a hose down the elbow results in the sound of running water, but nothing appears in the foul drain (the drop at the elbow would intersect the foul system between the next semi and us). The property search suggests a combined system, and the heavy clay would seem to rule out a soakaway. Would an optical search with a camera seem a good idea? I'm worried that there might be more clay related problems going on, which might get b....y expensive! (the sewer is about 4ft deep). Any thoughts much appreciated.

[welsh brickie]

I would forget trying to find where the pipe goes and block it up.
Its best to lay a new pipe directly to the foul manhole,The pipe could be cracked further down and the more water directed into it could cause more damage.

[marktheherald]

Further investigation in nextdoors garden ('upstream' in the system) has revealed a second manhole near to their foul manhole. The second one would appear to be a surface system, although it runs at a similar depth to the foul. When I run my hose into my broken pipe I can hear it running in next doors surface system. I am going to re-instate the pipework using plastic parts and then monitor the drainage when it next rains heavily. welsh brickie, thanks for your suggestion, it may well come to that, but we shall see.