New WC drainage

[DickieA]

Can anyone tell me what drainage arrangement I need for adding a WC into existing drainage for the house in the layout shown in attached image please? Think I know roughly but want to make sure nothing will cause issues with building control.

I'm thinking:

New ground floor WC 4" waste exits through cavity wall into boss outside (gap between houses is about 600mm) which would also take 40mm waste from hand basin and have rodding access. Do I need an AAV on this? ( There are no windows down the side of either house). Run pipe clipped to side of house to the back corner then dive down underground and across back of house to meet and tie in to pipe running from main SVP to the inspection chamber. (Approx 500mm below ground) Existing underground pipe I think is Victorian clay - the inspection chamber is very smart old brick work.

 

[Newboy]

What distance involved and exactly how deep is the foul drain at the point where you plan to join to it?

You need an access chamber at the new junction and likely at points where there is a change of direction. It would be preferable to go underground at the point where you exit the building rather than above surface.

 

[DickieA]

It's approx 5m from where it would exit the side wall of the house to the back corner then 4m across the back of the house to the line of the existing underground soil pipe. I haven't dug down to check yet but having looked into the manhole at the end of the garden that is about 500/600mm to the bottom. Will get some more detailed measurements and photos put up on here tomorrow.

 

[Newboy]

A photo of the inside of the existing chamber would be useful - it might well be an interceptor if it's on a Victorian combined system.

 

[Ian H]

You might be better with it joining into the manhole.

 

[bobasd]

get bco on site for an opinion. they might give you a pass for whats in-situ and proposedand some useful on site advise

 

[DickieA]

Thanks guys, some more photos for reference....

 

[Newboy]

That's a rather nice Victorian interceptor/Buchanan trap in good condition. Looks like there was a vent to the chamber which would have been connected to something like this

Need to know the depth of the main channel from surface level and if there is any slope from your house to this location

 

[DickieA]

Yeah I thought it looked pretty smart when we lifted the cover! Will have a dig at the weekend and report back. Thanks for advice so far

 

[bobasd]

dont know what this business is with interceptor trap and a FAI and depth of foul drain line?
what do you want to dig for this week end?

the side inlet in the manhole might be from the kit sink gulley, easy to check.
youve probly got a hip rear roof so why two rwp's? you only should need one.
where your sewer goes to connect to the mains beyond the boundry there should also be a man hole.

as above, connect the proposed drain to the garden manhole.

 

[Newboy]

the side inlet in the manhole might be from the kit sink gulley, easy to check.

Unlikely - it's on the wrong side of the chamber, at the wrong height and would have to cross the main line to get to the chamber.

 

[Newboy]

Yeah I thought it looked pretty smart when we lifted the cover! Will have a dig at the weekend and report back. Thanks for advice so far

No need to dig - measure from the ground level at the chamber down to the bottom of the channel.

 

[bobasd]

if the photo is lookin upstream then the kit gulley branch comes inon the right. theres nothin drainage wise showin on the left side of the yard.

still dont know why the invert depth needed unless you wanted to start rearrangeing it?
youve got plenty ofdrop over 4M to 6M of garden tothe 25" to 27" invert depth in the manhole.
Regs require min. drop of 25mm/1M.

 

[Nige F]

Thanks guys, some more photos for reference....

Interceptor trap @ top of photo. vent near top of manhole on right

 

[Ian H]

if the photo is lookin upstream then the kit gulley branch comes inon the right. theres nothin drainage wise showin on the left side of the yard.

The trap is at the D/S end so the photo is kind of upside down.