Backdrop Manholes

[Ukjay]

Hi,

Has anyone had any experience with using the above solution to get the foul waste to a treatment plant due to the ground being sloped. I have the go ahead to install the tank where I wanted to, so now I need to think seriously on the backdrop manhole system to get our levels to work, as this has been suggested as the best route, hence wondering if anyone had gone through this and is it worling OK.

The drop from start (house existing external pipework) to entry into the Treatment plant will be circa 3.1m which is needed over a run of circa 36m run (I have not physically checked the existing pipe depth in the field yet, so may be a bit less). The tricky area is next to where the tank will be going, as that has a slope leading down to it that will get smoothed out a little to reduce the gradient, but will still be quite steep.

This is the preferred design into the manhole specified:

 

[Forever Fendt]

yes no problems at all saves lots of digging

 

[Ukjay]

yes no problems at all saves lots of digging

Could you offer some ideas into how you would manage to set them out please, as I have this to contend with which is the bulk of the drop I need

:

 

[Forever Fendt]

I can’t quite grasp what your draining and where to give me a bit more info I take it it’s foul drains

 

[Ukjay]

I can’t quite grasp what your draining and where to give me a bit more info I take it it’s foul drains

Hi

It is the house foul drain being rerouted from the failing septic tank, which has to drop circa 3.1m from the house existing foul pipe level, and the area the new treatment plant is going is adjacent to that slope next to the barn (dug in and backfilled with dry cement mix). The invert of the inlet to the treatment plant is 575mm.

The run from current house foul pipe to the top of that slope is circa 30m.

As I've never done backdrop manholes before, so wanted to get my head around how they worked in series, as the minimum is 2 required as there is nothing I can find on the net other than basic pics.

The bit you see next to the barn is where the treatment plant will be installed (dug in)

 

[Forever Fendt]

I have sent you a rough sketch on pm

 

[Ukjay]

I have sent you a rough sketch on pm

Thank you, very much appreciated. I have replied

 

[diggerjones]

Think now a days you can go steeper with falls. The reason being using 6m length plastic pipe is alot smother than old clay pipes. You need to check.
The drop shafts I've done are drop shafts, not ramped.

 

[br jones]

Think now a days you can go steeper with falls. The reason being using 6m length plastic pipe is alot smother than old clay pipes. You need to check.
The drop shafts I've done are drop shafts, not ramped.

You must be careful to slow the crap down and not cause a splat ,that is how my bc man described it !

 

[Forever Fendt]

Think now a days you can go steeper with falls. The reason being using 6m length plastic pipe is alot smother than old clay pipes. You need to check.
The drop shafts I've done are drop shafts, not ramped.

you have to be careful you don't get separation with the solids from the water if you go to steep and modern toilets with reduced flushing capacity won't be a help

 

[Ukjay]

Think now a days you can go steeper with falls. The reason being using 6m length plastic pipe is alot smother than old clay pipes. You need to check.
The drop shafts I've done are drop shafts, not ramped.

A fall greater the 1:40 runs the risk of leaving the solids in the pipework, as the fluids will in turn travel faster creating potential blockages, and regs give you the falls you need to work with.
If it's just rain water drains, falls are not so critical as you are not moving solids, so falls used could be steeper.

The reason for the ramped back drop is what 'BC' stipulated as their preferred option, along with having 2 of them in this line.

 

[Doing it for the kids]

Not read full thread but did this for a whole village.

I hUsed 6 inch pipes so I don’t ever have to unblock it.

Trick is to get fall slow enough to float solids down rather than race down leaving behind.

Work out total distance and then work out fall you can safely used. What ever is left needs to be dropped as per pics above. Make all manholes super smooth so nothing gets caught and leave ridding eyes etc to clear a blockage.