Drainage design

[Heather2011]

Hi,

Could anyone shed some lights on whether the drainage below would work or not? I've attached the Building Regs drawing below. The green lines are existing drainage and the red ones are to be built.

The idea is to build a new shower room and use an existing FW as MH and connect all drainage (e.g. sink, toilet and shower) from the new shower room to the FW. Note that kitchen sink is also connected to the FW at the moment. My question is, is it appropriate to let toilet drainage share the same FW with others such as kitchen sink, especially consider that they are all quite close to the FW. Is there any risk that the toilet smell will come out from kitchen sink or bath tub?...

Thanks,

Untitled

• Heather2011
• 14 Sep 2011
• 1

 

[freddiemercurystwin]

All sanitaryware items and sinks have a water trap seal between the sewer pipe and the air inside the room. Do your existing toilets smell of sewers? Thought not!

 

[Nige F]

: I`d rather see FW1 in the garage not in the living area - double sealed cover or not - it`s only a bit more green ink on the plan probably worth the efort to move it during the build - will make maintenance easier in future . Water traps on appliances other than WC`s are old fashioned - I would use Hep V O waste valves myself

 

[RedHerring2]

Is the new gulley from outside feeding into the foul water system?
You appear to have a seperate surface water system, yet this guley does not feed into that.

Has this been accepted by BC?

 

[Static]

Having an internal manhole at the head of a run is a bad idea.. you really really dont want to be opening it up in your living room..

Also the bathroom pipe running through all the new foundations simply wont work.

Better solution would be rodding eye by the gully, manhole on corner of extensions, turn 90deg to second manhole outside living room patio doors which collects the three pipes then into the main run..

 

[^woody^]

There are too many drains.

It should be designed as one main drain, with the others feeding in to it. And ideally the single drain wants to go through the foundations at 90 degrees, not at those silly angles. So perhaps move that manhole where they all connect to over to the left, to be in front of the elevation

Can't the basin waste go into the svp, instead of having its own drain?

There is scope to keep the manhole out of the living area, so it should be done

 

[noseall]

Agree with Woodshavings.

The angles at which the drains intend passing through the walls will not work.

I would look to use the garage as a possible site for an i.c. and/or a stub stack. I am thinking of orientating the shower base so that the waste is on the outside wall, running into the garage (which should have a lower floor) and then going into a stub stack located nearer to the loo.

Woodstocks' suggestion of locating a collecting chamber in front of the living room makes a lot of sense.

How deep is the lowest chamber? What are those figures referring to i.e. invert and cover level 9.850 etc? Surely not 9.850 Metres!

 

[theoldun]

Read your PM will try and reply to-morrow.

Regards your drainage. Completely unpractical. Could be made to work with quite a lot of modification, but big problem then, is that there are a couple of very keen BCOs in the Dunstable area and as the existing drains will be running under the new oversite, they will probably insist on an air test.
If property is from the 50s, then good chance that existing drains are salt glazed with sand and cement joints or worst still pitch fibre, and in all probability will not stand a test.

Would suggest you determine material of existing drains and then put an air test on them so that you know whether they will stand up. Do not bother with the third one on right hand side as this can be done away with.

When you have this information then you can decide what to do, but I would suggest that you prepare yourself to re-route and renew all drainage.

If you want a price what that should cost you, then come back and we will knock you out a few figures. However we will require further information.

Nose. Note your question. Not telling you how to suck eggs. but all reduced levels are taken from a datum. In this instance they have taken the FFL level as datum of 10.000, shown in the hallway.
Top of manhole cover is given as (wish my sight was better), appears to be 9.800, therefore manhole cover is 200mm below floor level. Get it?
Invert level is given as 8.950, therefore invert (channel) is 1050 below floor level and 850mm below cover level. Got it.
Works other way round if level is above datum. Say manhole cover was 300mm above FFL then reading fpr cover level would be 10.300.
All roads, estates, big muck shifting jobs are worked on this method.
Regards oldun

 

[noseall]

Nose. Note your question. Not telling you how to suck eggs. but all reduced levels are taken from a datum. In this instance they have taken the FFL level as datum of 10.000, shown in the hallway.
Top of manhole cover is given as (wish my sight was better), appears to be 9.800, therefore manhole cover is 200mm below floor level. Get it?
Invert level is given as 8.950, therefore invert (channel) is 1050 below floor level and 850mm below cover level. Got it.
Works other way round if level is above datum. Say manhole cover was 300mm above FFL then reading fpr cover level would be 10.300.
All roads, estates, big muck shifting jobs are worked on this method.
Regards oldun

Got it as soon as you said datum.

 

[Heather2011]

Hi all,

Thanks very much for everyone who replied - that was very useful information, pointed me to the potential risk that I wasn't aware of.

I have spoken to my architect since then about the risk of the internal manhole and the angel the drainage pipes go through foundation. A couple of things:

- One of the existing drainage pipes (the green one on the very right) will be disused, which means we'll have only one drainage pipe from the bathroom. Will this make any difference? and just for my own information, why does drainage pipe has to cross foundation in 90 degree angel? What are the risks if it's not 90 degree?

- The reason for an internal manhole is that we don't have enought space outside the extension to build a manhole. Note that the garage shown on the drawings doesn't belong to me. The other reason for the internal manhole is to minimise the drainage ground work. In terms of the risk of blocked manhole, he has designed a gully connecting to the manhole and can be accessed from outside - will this help?

Appreciate any thoughts!

 

[Heather2011]

Read your PM will try and reply to-morrow.


Nose. Note your question. Not telling you how to suck eggs. but all reduced levels are taken from a datum. In this instance they have taken the FFL level as datum of 10.000, shown in the hallway.
Top of manhole cover is given as (wish my sight was better), appears to be 9.800, therefore manhole cover is 200mm below floor level. Get it?

I think the manhole is about 1m deep? Just checked over the weekend and it doesn't look like 2m deep to me... I actually thought the depth of the manhole is the difference in the two figures, i.e. 9.85 - 8.95 which comes to 0.9m? Please shout if I've got it completely wrong!

 

[Heather2011]

Is the new gulley from outside feeding into the foul water system?
You appear to have a seperate surface water system, yet this guley does not feed into that.

Has this been accepted by BC?

Yeah, I think the new gully will feed into the foul water system. Is gully used to collect surface water or can it be used as an access point to the internal manhold, e.g. like a rodding eye?

by the way, the building regs drawings have been approved by the building control company.