In an earlier contribution to this discussion,
Phil L wrote:

Roger Mills wrote:
In an earlier contribution to this discussion,
Adrian wrote:


The trick is to find the first point *downstream* which *isn't*
blocked, and then rod in an upstream direction from that point. If
you try to rod from one that's full, you can't see where the outlets
are - particularly if it's deep (mine are all 2 metres or more!)

Have you any idea of the force behind all this sewage?

Yes, I have! Two 6" public sewers meet in a manhole at the bottom of my
garden - and one or other of them has blocked quite a few times in the 30+
years that we have been living here.

- surely
standing downstream of what could be 2 tonnes of untreated sewage and
water is not a good idea, as I found out when I was much younger -
you want to push it away from you, not pull it towards you, cos when
it goes, whatever manhole you are working on will fill up with such
ferocity that it's likely to continue in an upwards motion for at
least 8 feet, and then come back down again

Whenever Severn Trent have come to unblock them, they have *always* jetted
upstream from the manhole where the sewers meet. Needless to say, they don't
actually climb into the chamber - they do it all from ground level - because
it does come down with some force, and starts to fill the chamber, once the
blockage has been shifted. But nothing has ever overflowed in the process -
or even splashed over the top. The chamber is over 2 metres deep - and quite
large in diameter so it has quite a large capacity to buffer transient
flows.
--
Cheers,
Roger
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