Foul drainage 101

[Moonshine]

I am thinking about the practicalities of getting foul drainage from a new plot on my land to the existing foul drain of the existing house, a distance of about 25-30m. This would go under the existing houses lands new drive, so in effect it will become a sewer.

 

For this i want to know if the invert levels can be accommodated under the topo accounting to level changes and the invert level of the existing drain it would feed into.

 

The reason for this is that it would save a lot of cost and hassle connecting to the sewer under the road as its a busy road.

 

I want to understand/confirm;

 

• Is the best/only design resource needed Approved document H.
• The vertical distance below the FFL of the house that the foul drain can start moving to the side from the stack location (ADH has this at 1.3m in some situations).
• The minimum internal diameter of the pipe (75mm?) required.
• The minimum fall of pipe (ADH seems to have this at 1:80 / 12.5cm every 1m) required.
• minimum depth of pipe under ground level (ADH seems to 150mm from the crown of the pipe)
• Man hole covers at every junction point
• rodding access points? 

 

Cheers

[Mr Punter]

• Is the best/only design resource needed Approved document H.

Most of the pipe manufacturers have design guides.

• The vertical distance below the FFL of the house that the foul drain can start moving to the side from the stack location (ADH has this at 1.3m in some situations).

No comprende

• The minimum internal diameter of the pipe (75mm?) required.

110mm O/D plastic pipe is standard

• The minimum fall of pipe (ADH seems to have this at 1:80 / 12.5cm every 1m) required.

Yes. 1:60 even better

• minimum depth of pipe under ground level (ADH seems to 150mm from the crown of the pipe)

As long as it is protected and pedestrian only area

• Man hole covers at every junction point

Preferred but not always essential

• rodding access points? 

Not always needed if you have inspection chambers

 

[Adam2]

2 minutes ago, Mr Punter said:

• The minimum fall of pipe (ADH seems to have this at 1:80 / 12.5cm every 1m) required.

Yes. 1:60 even better

 

I had understood ( as someone that is learning so not saying this is correct ) that 1:80 would mean 1cm drop per each 80cm in length. 

 

[Mr Punter]

1 minute ago, Adam2 said:

 

I had understood ( as someone that is learning so not saying this is correct ) that 1:80 would mean 1cm drop per each 80cm in length. 

 

 

I think he meant 12.5mm

[Moonshine]

Just now, Mr Punter said:

I think he meant 12.5mm

 

correct, typing quickly and d.p in the wrong place. Thanks for your response very helpful

[Adam2]

Good to make sure - don't want your sewage going to Sydney, even more rules then ?

[Moonshine]

9 minutes ago, Mr Punter said:

• The vertical distance below the FFL of the house that the foul drain can start moving to the side from the stack location (ADH has this at 1.3m in some situations).

No comprende

 

fair enough, i probably didn't explain it correctly, see the figure below, this is the maximum value invert level, is there a minimum value? 

[Moonshine]

5 minutes ago, Adam2 said:

Good to make sure - don't want your sewage going to Sydney, even more rules then ?

 

stop it you will give me flash backs of the BCA!

[Mr Punter]

45 minutes ago, Moonshine said:

 

fair enough, i probably didn't explain it correctly, see the figure below, this is the maximum value invert level, is there a minimum value? 

 

No minimum.  It is normally the long radius bend at the base of the stack and your floor makeup that will decide.

[Moonshine]

1 minute ago, Mr Punter said:

No minimum.  It is normally the long radius bend at the base of the stack and your floor makeup that will decide.

 

Thanks, iirc its a 200mm radius bend (ADH)