Extended Rest Bends: when to use .... ?

[ToughButterCup]

Sometimes I've been known to use the bathroom as the place to take an extended rest. But I didn't know that I might have been sitting some way above an extended rest bend.

I'm wondering what the criteria for use is?

Is it simply to increase the reach of the bend, or might one be used when there's an increased likelihood of differential ground movement?

Our land profile near to the raft is MOT1 on top of topsoil, and that's on clay. The foul drain comes out of that 'mix' and  then descends steeply (it drops about 2 meters) through more topsoil and then into wetter clay. And straight into the digester.

 

All of the pipe is at least 1 meter (usually more) below the ground surface. 

I'm overthinking it aren't I?

 

PS, MOT1 is the worst , the very worst stuff to dig through by hand innit? Gimme clay any day.

 

 

 

 

[JFDIY]

Think it's for where the vertical leg might move relative to the drain run in the ground, so a tall stack subject to thermal movement, or as you say ground likely to move settle.

 

However if the vertical pipe is not secure or it is bottomed out in the joint to start with then it could well be a wasted excercise

[Bitpipe]

41 minutes ago, AnonymousBosch said:

PS, MOT1 is the worst , the very worst stuff to dig through by hand innit? Gimme clay any day.

 

Yep, last spring I cleared out a patch next to the house paving to sink some clay pots to build a little herb garden. A full foot depth of compacted MOT1.Took me most of a week.

 

I find a pickaxe is the best way to get through it and loosen it up, alternating between the pick and blade. Spades and shovels are very hard work as they just keep pinging off the rocks - much easier once the pick has loosened it all up.

[ToughButterCup]

29 minutes ago, JFDIY said:

Think it's for where the vertical leg might move relative to the drain run in the ground, so a tall stack subject to thermal movement, or as you say ground likely to move settle.

 

However if the vertical pipe is not secure or it is bottomed out in the joint to start with then it could well be a wasted excercise

 

Thanks. There's little to be lost by fitting one at the bottom of the vertical run  is there? And it would be a right royal pain in the Botticelli to have to replace a normal rest bend for an extended one .

 

1 minute ago, Bitpipe said:

[...]

I find a pickaxe is the best way to get through it and loosen it up, alternating between the pick and blade. Spades and shovels are very hard work as they just keep pinging off the rocks - much easier once the pick has loosened it all up.

 

Added to that I have the delight of that plastic-coated metal mesh support layer about 900 below the surface. Fantastic stuff - saved hundreds of pounds worth of MOT1 and associated transport costs. But a serious annoyance now.

 

Still, look on the bright side - got rid of a few calories

[dpmiller]

Local BCO doesn't even require *normal*  rest bends never mind extended. Bog-standard 90 at the base, round these parts...