New Gully feeding into existing manhole.

[RedHerring2]

I'd appreciate your thoughts/opinions &/or advice.

I'm currently at the below dpc brickwork stage on my current extension.
I have a concern about the new gully for the bathroom (to take bath/shower and whb waste water)

Existing plan shown here:
View media item 25995
Proposed new extension shown here:
View media item 25994
The problem that I have is:
The architect shows waste water from the whb bath/shower discharging into the driveway at the side of the house. In order to avoid loss of width of the driveway &/or damage to pipework I'd prefer to install a new gulley at the rear of the house. Like as shown on this diagram:
View media item 27343
However, to achieve this will mean introducing the flow of waste water against the natural flow of the drain. We are the highest of the drain, so no-one is affected upstream. The manhole brickwork and benching is in good order.
Now I realise this isn't good practice but after more thought I can't really see anything wrong with it, in this instance, although it would mean introducing that waste water higher than the invert level, which again is not good practice. It is only the waste water from the bath/shower and whb. The WC's are still discharging via the existing stack.

But another concern is that 'cos the drain is only 350mm from the outside of the wall to the centre of the drain run (old salt glaze 110mm) the new plastic pipe from the gulley will run almost directly above the old salt glaze pipe run. Is this acceptable? Are there any regulations governing what is acceptable? I would probably encase the both in concrete.

One of the other options I can see is to provide a new short stack within the new bathroom but I don't fancy this and I would still need to run new pipework above existing pipework, to an extent.

The other option is to run the new bathroom gully into the proposed new manhole but this would require crossing the existing drain, at least a 45 ° bend, then within about 2 metres a further 45 ° bend into the new proposed manhole. Like this:
View media item 27344
The BCO is fully aware of the proximity of the drain to the wall and has not objected to anything. I haven't yet discussed the flow of the new gullies into the existing manhole.

I don't see any problem with the new proposed kitchen gulley and manhole although the new pipework will need more or less a direct drop into the new proposed manhole. I was intending to attempt to create a new manhole using the old, existing salt glaze pipework.[/img]

 

[Hugh Jaleak]

I dont really see the need to pipe the gulley into a manhole. The existing drain is accessible from either end for rodding, use a Bottle gulley and tee into the run. A Bottle gulley will allow access for rodding, in the unlikely that short run from gulley to drain blocks.

 

[RedHerring2]

Isn't it always the way, the simplest answers are the best. I didn't see it and thought I had to connect to the manhole. Thanks , you've made by day. I've spent best part of the afternoon trawling through Approved Document H.

I think I'll still have to build the new manhole 'cos it's on the plans and BC have approved them. Although there is another manhole next door, downstream about 25 metres away at max. I'll discuss that option with the BCO. You never know I might get away without a new manhole.

Edit: Aah, just realised, that'll incur me replacing some of the old salt glaze for new plastic. But it's still the easier option.

 

[Hugh Jaleak]

I'd speak to B.C.O. 25m isnt a long distance between manholes, and all you're doing is adding a couple of connections, they may be ok with bottle gullies. Main concern with drainage is access in event of blockages.

Only issue with the salt glaze is its fragility, you may find the pipes and/or joints fall apart, so exercise caution when excavating/cutting pipes. If you use the 'Fernco' type couplings these will slide easily onto the plastic spigots, then slip back onto the salt glazed, so minimising the section of salt glazed you need to remove.

 

[RedHerring2]

Thanks again. That's what I'll do, I'll talk to BCO see if we can get away witout the additional manhole. Architect has admitted to being a belt, braces, string, shock chord type person when submitting plans.

And I'll look out for the Fernco type slip couplings. I would otherwise have used the basic type slip coupling from somewhere like Selco or Jewsons.
I gather, having looked them up on the 'net, the difference is that Fernco type have 4 jubilee type fixings rather than the basic two?

I guess the ease with which the old salt glaze may come apart is an advantage on the upstream end. It's on the downstream end that I'm gonna have to cut the pipe. If I can just cut off the flange I should be able to leave most of that bit of pipe still buried. I have a small (125mm ) grinder so I should be OK.

 

[theoldun]

Jim, As you have helped a lot of people out on here in the past, will throw in a few thoughts for you.
Yes Hughs idea is a good one, and would have been top of the list on our first thoughts, how ever, couple of things to think of first.
1. If your BCO insists on a test for the new drainage, that means that you have got to put the test on the old salt glazed as well as the new, as you can not get a plug in to the new branch. You may be lucky and the old run will stand up, but you know what they say about s*ds law. Would sound BCO out first before hand regards testing or put a test on it first before breaking in to it.
2. You state that the centre of drain is 350 from external skin brick work. If you dug your founds 1000 deep by 600 wide and trench filled 750 deep, the invert level of the salt glazed is 300 below top of foundation, which leaves 200 from centre of drain to face of concrete founds, which is not sufficient to fit a 45 degree equal branch and 45 degree bend. If you dug 450 wide this will leave 275, which may, repeat may, just allow you to get in by chopping out bit of concrete down face of con founds. Some BCOs allow you in cases like this (water only, no solids) to fit the Y pointing up vertical, but then again some have refused this in the past and want the Y horizontal and on same level as run.
Not trying to put a damper on Hughs sensible suggestion, but in your instance due to the close proximity of existing foul run to brickwork and foundation, I do not think that you will get it in.
There is a way of doing it to satisfy the regs, how ever as I do not know how to post drawings etc, if you PM me (think that is the wording) with your address, will do you drawing, explanation and post it to you.
oldun

 

[RedHerring2]

Thanks for your input 'oldun. I've been watching GP on TV accompanied by best part of bottle of wine so forgive my spelling and if I don't get to grips with all of your post.

Firstly, fully appreciate your advice about old salt glaze, in fact the old junction from existing kitchen gully (not indicated on existing plans, but just outside of kitchen window) is leaking under heavy load, e.g washing m/c discharge etc. No great shakes as it will become a redundant branch, as soon as new gully is functional. BCO is happy for it be simply encased in footings and trenchblocks without lintels. I'm guessing here and from memory, the invert level is only 100 - 200mm below top of footings, and only 100 - 200mm away.

Secondly, footings was 900mm deep, (600mm wide) but just 300mm thick(Spec was 275mm), then 275mm wide trench blocks ( two courses) which brings me approx 75mm below ground level. So I'm hoping I might just squeeze it in, with almost a vertical drop into existing (well re-newed plastic) pipework.

I'll draw it out later, when I'm recovered.

I will PM you, 'cos your contribution to the forums are appreciated, and with the ability of posting drawings will increase immensly, I'm sure.

 

[RedHerring2]

There is a way of doing it to satisfy the regs, how ever as I do not know how to post drawings etc, if you PM me (think that is the wording) with your address, will do you drawing, explanation and post it to you.
oldun

'oldun, try clicking on "Help" (next to "Rules" above), then on "Formatting";"Can I post Images"

See how you get on.
You've helped a lot of people on here, I'm sure, if you asked, they'd be only too pleased to have the opportunity to reciprocate.