Underground drainage planning.

Hi,
we have got a build over agreement with Southern water to change our drains about as we are building a new extension.
The drains at the moment are like this,


Southern water insist we use concrete and brick manhole where the neighbors and our drains connect.

As far as I can see we cant have 45 degree bends underneath as they need inspection chambers at change of directions, why do companies make 45's then? Surely they are never used?

This is my plan...


This involves two inspection chambers though, after the manhole, would this be acceptable? or can I leave one out? a rod will surely get round a 45. I could even use 3x 30 degree ones and then just have that one manhole going in?

I have asked all this and more to Southern water, however they were no help at all, I asked how we could connect the neighbors drain considering it needs to go to the new manhole and they said 'you can't'... Helpful

I will email over my final ideas to them to check and okay, but obviously only want to do it the once.

Any thoughts would be appreciated.

Cheers
Edd

In the grand scheme of things the cost of having 2 inspection chambers as opposed to 1 is not all that great and it could save you a whole load of haslte and cost further down the line.

Have you had a chat with your local building control? Considering this is reportable work, it makes sense to ok any plans with them before sending it on to Southern Water imo.

The reason for 45 degree bends is sometimes a drain requires an offset to take it lower. Building regulations document H may be able to assist you as well as local building control. Is there any reason you can’t just relocate manhole or supply an inspection chamber on the straight after your extension?

As above, this falls under 2 areas of control.

Southern Water who from 2011 own and maintain all private sewers in their area and will take ownership of the new common drains you are installing, as similarly do all other Water companies.

You have to meet their requirements as owners.
They are not there to offer a free design service.
You have to allow them access and pay for their surveys.
You'll need better than a sketch for them to approve.
Water companies did not ask for the ownership of private sewers, it was thrust upon them by Government and they've had to take on a right pile of cr*p underground.

Drains are also covered by Building control, so you have to meet their requirements as well.
If you use Private Building Control, they'll be more helpfull and quite often cheaper.

You should be able to miss out the second proposed I.C and put a 45 bend at the junction with the existing sewer chamber.

I never mess with the utilitys is easier in the long run to suck it up and do as they ask. lessons long learned as a young developer ..centralheatking

Thanks for your quick replies.
Yes I have spoken to building regs, they informed me that for all drainage needs I must contact Southern water.
We have already got the build over agreement but im pretty sure it was a blanket approval as the letter had clearly been sent out multiple times before, of course this is no problem.
I want to send them a proposed plan with pictures and details so they can check it over and tell me if I am missing something.

Had originally wanted to put the MH on the stright, directly after extension but then have the issue of getting the neighbours drain to it somehow considering I cant have any 45's in there.

I see what you mean, I could have just one extra IC as it can be rodded from both ends, but obv part H says you need access points at all changes of directions.

What does make me chuckle is that there are all kinds of drain bends under our house already!! typical

Cheers
Edd

I couldn’t download attachments to my iPad to confirm what I mean, but looking at both diagrams your neighbours already connects in at MH in first diagram? If so, then just add the additional IC in the straight. As for changes of direction it states it should have one. Also I’m not sure theirs would be a change in direction as I think theirs connects to the main line as what’s known as a slip. All you do is submit your proposal to them and ask them to reply.