"half pipe" for bottom of foul drain manhole

[Caecilius]

A little bit OT, as I'm getting a builder to do the work, but...

I'm diverting a 6-inch foul drain as part of a new build project, to avoid building over it. I need to put a 45 degree bend in, and I'm planning to build an inspection chamber/manhole to do this.

My builder is fine with building the manhole, but doesn't know where to get the "half pipe" to form the bottom of the manhole where the foul water will run.

An example of an existing manhole on this drain is here:

it possible to buy clay pipe sections for this, or do you buy the pipe and cut it with an angle grinder?

I'm guessing I could get a 45-degree clay pipe bend and then cut it, but I want to check I'm not going the wrong way about it.

[charles]

Is it possible to buy clay pipe sections for this, or do you buy the

When I rebuilt some drains in the late 1960s I had no problem getting clay half pipes.

I note that Hepworth - large maker of underground system bits still have them on their website - called "drainage channel". Hepworths also have a list of stockists on the website. Probably any decent builders merchant can supply something similar.

[Nightjar]

> Is it possible to buy clay pipe sections for this, or do you buy the

They are called channel bends and should be available through any builders' suppliers, although possibly not from stock.

Colin Bignell

[Phil L]

> Is it possible to buy clay pipe sections for this, or do you buy the

You can either buy the half pipe 45d bend*, or buy a regular bend and cut an openeing out of the top - note, it doesn't need to be split in half - a 3-4 inch wide slot about 8 inches long is more than enough to get rods in, which is it's only function really.

• V V expensive compared to a full bend.

You may be able to buy the pre-moulded underground plastic manhole base with the bend you require, here's an example of one:

[The Natural Philosopher]

you just buy a pre configured unit and set it in ballast or concrete

It really is that simple.

[NT]

Other option not yet mentioned is to freehand it.

NT

[John Rumm]

> Is it possible to buy clay pipe sections for this, or do you buy the

You can certainly get them, in plastic as well as clay. For example:

(a couple that are sat in my shed doing nothing if you want them)

[Caecilius]

I wish it were that simple.

Thames Water, who own the drain, want a conventional inspection chamber rather than a pre-fabricated plastic jobbie. They also want traditional clay pipes rather than plastic.

If they're not happy, I don't think the BCO will approve it, so I need to do what they want.

[Caecilius]

I've not heard of this method. Does it mean casting the base out of concrete? Is that smooth enough and suficciently impermiable compared to salt-glazed pipes?

I'm not sure Thames Water, who need to approve the job, would allow it, but it sounds interesting.

[Caecilius]

Thanks for all your help chaps. I got the channel bend from a nearby build centre. Quite easy once I knew what it was called, although I had to phone around a bit before I found one that did clay - lots of places only stocked plastic.