"Tim Lamb" wrote in message
...
In the words of Kipling, an offensive effluvia has been noted in our
entrance hall.

There was a slight back up when I lifted the manhole covers but no real
blockage. Anyway, after rodding and flushing I had a peer around with a
mirror on a stick and a torch. Two points of interest for which comments
and advice are sought....

Where the new soil pipe for our extension is coupled in to an
existing manhole there is a gap in the haunching which might allow
backed up dirty water to leak into the trench and seep through the pea
shingle back under the house. I have plenty of soft sand and masonry
cement to hand but is there a special mix for the job?

The second issue is that, for reasons only known to the drainage
contractor in 1975, our soil pipe starts as 6" salt glaze, travels round
the side of the house (90 degree bend with inspection pit) reaches a
second pit still in 6" and then reduces to 4" plastic! Not only is there
ponding at the reducer but the pipe used has a spiral scroll inside;
surely not intended for this use.

The cure must be to *up it* and re-do. Not easy as it is about 3'6" down
in a tarmacced yard. But, does anyone know why this reducer was used?

regards

Tim Lamb


I take it this drainage system is for solid waste removal, correct? If it
is, then you do have the wrong type pipework in place, don't you.

Any system meant for solid waste removal must continue in pipework that is
as smooth as is at all possible. As you can imagine what happens when this
type of waste product comes in to contact with rough surfaces or spurious
protrusions.

Although, that said, there are cases where waste systems must be slowed not
to cause conflict with connections further down the line, but these are very
few and far between. But I have to ask a question here, and it's to do with
the pipe you say has a spiral inside it (?). Does this pipe drop away
almost vertically? Or at least beyond an angle of 65 degrees off
horizontal?