Foul Drainage - Am I going to have problems ?

[self builder 123]

Hi

We recently installed our 110mm underground plastic foul drainage pipe work. We used continuous lengths of pipe where we could bedded on 10mm pea gravel.

Where the pipe changed direction we used sweeping bends and installed and inspection chamber at the same time.

At the head of the longest run there is a bath, shower, whb and WC.

The run measures approximately 38 metres from this bathroom to the main sewer.

It has come to my attention that on the advice of the local BCO a graident of 1:100 was used, even though we had read that it should be 1:80 minimum with a WC.

As I understand it the height of the main sewer was partly to blame for this reduced gradient.

We have yet to use the WC so I am not sure if we are going to have problems.

A lot of care was taken when the pipe work was installed to ensure that the runs were as smooth and straight as possible.

Based on this info and the 1:100 gradient can anyone tell if we are going to have problems with blockages when we move in ?

Cheers

 

[fatplumber]

Get a wooden ball and roll it down it. If it goes then you'll be ok.

 

[Agile]

A fall of 1:100 over 38 m would need a very careful setting out.

I would expect a laser sight would be needed to establish a constant gradient.

Tony

 

[self builder 123]

Hi

Thanks for the replies.

The 38m run turned 2 twice through 90 degrees :

9m run - 90 deg turn - 6m run - 90 deg turn - 6m run - Back Drop - 17m run direct to main sewer. Last 6m of run is in 150mm plastic pipe as it leaves the boundary and crosses under the road to the main sewer.

 

[self builder 123]

Hi

Can anyone else offer any experiences of drainage with a 1:100 gradient ?

 

[fatplumber]

Sorry mate but most of us wouldn't work yto such fine telerances. 1:100 should be fine but you have little margin for error. When I started we worked on min of 1/2" to 6' so what's that? 1:150 but that was in LCC above ground and we could be very accurate.

 

[Hugh Jaleak]

I think you can only wait and see. Might be ok, may block quickly, may block slowly over time. Provided the fall has been constantly maintained then it may be ok, after all B.C.O. seemed happy with it.

If the invert of the foul main in the road isn't deep enough to achieve a greater fall from the property then the only other option is to pump the waste back up to the higher point and allow gravity to take over again.

 

[self builder 123]

Many thanks !