New drain connection advice

[d438a1]

Hi there,

I'm in process of running a new drain at front of house for a new upstairs bathroom. I've dug out where it needs to connect to and got a rough idea of what I hope to do now. I've got the building inspector coming at end of week but wanted to check views here first.

As you can see from attachments the connection is very close to the Sewage Treatment plant (STP). The inlet to this is around 1.3m deep where the main line from back of house runs. There is also a separate drain connection that runs alongside this and drops vertically which comes from garage.

Unfortunatley it seems like they have bedded it partly in loose concrete and it's proving hard to easily excavate under the pipe to get an inspection chamber base in. So in the sketch I've shown in the dark colour pipe my proposal instead with an extra rodding point as well (if necessary). The new connection is a straight run about 15 metres and will have an inspection chamber and the main existing drain. also has an inspection chamber about 12 metres away. And the drain from garage also has an inspection chamber about a metre away next to STP.

Also, yes I'm pretty sure the water is ground water and not a massive leak from the STP. I recently moved in to house and had all the drains surveyed and they all seem fine.

So, does my proposal seem ok?

Thanks

 

[noseall]

Hi there,

I'm in process of running a new drain at front of house for a new upstairs bathroom. I've dug out where it needs to connect to and got a rough idea of what I hope to do now. I've got the building inspector coming at end of week but wanted to check views here first.

As you can see from attachments the connection is very close to the Sewage Treatment plant (STP). The inlet to this is around 1.3m deep where the main line from back of house runs. There is also a separate drain connection that runs alongside this and drops vertically which comes from garage.

Unfortunatley it seems like they have bedded it partly in loose concrete and it's proving hard to easily excavate under the pipe to get an inspection chamber base in. So in the sketch I've shown in the dark colour pipe my proposal instead with an extra rodding point as well (if necessary). The new connection is a straight run about 15 metres and will have an inspection chamber and the main existing drain. also has an inspection chamber about 12 metres away. And the drain from garage also has an inspection chamber about a metre away next to STP.

Also, yes I'm pretty sure the water is ground water and not a massive leak from the STP. I recently moved in to house and had all the drains surveyed and they all seem fine.

So, does my proposal seem ok?

Thanks

I'm a bit baffled by what's going on there? Isn't that the run-off, you are proposing to connect onto, at the back/bottom of the tank?

 

[d438a1]

Hi. No, that is the main inlet in to the tank. The outlet is on other side

 

[Ivor Windybottom]

Given the already unconventional layout, that is probably the best you could do.

You seem to have pipes arriving from three completely different directions and doubling back on themselves. Is this a neighbourhood system or just yours?

 

[Ivor Windybottom]

Could you cut into that lower inlet pipe and insert a chamber with a side inlet for your new branch? Where I've put the two possible positions with green arrows.

You'd then avoid the Alton Towers style roller coaster bit and have proper access to the junction as you should.

It depends how many riser sections you'd need.

But... I don't understand why your inlet pipe goes in so low down, ours goes in just below the top and tips in. If that's the inlet then I can't see how that pipe could be anything other than permanently full of backed up raw sewage. Unless it's fitted really deep and your yellow cylinder is just a riser column above it, full of air?

Is it possible that this is actually the outlet, and the existing pipe that drops in is rainwater that's combined with the treated sewage coming FROM the treatment system?

Take the lid off, see what's what in there. If in any doubt get it completely emptied so you can work it out.

 

[d438a1]

Thanks for replies. Here's a photo of the tank, arrow is where that inlet pipe is coming in.

 

[Ivor Windybottom]

Ah OK, it's a long way down then. A Klargester by the looks of it. Does it still work?! They seem like a troublesome way of aerating the contents, ours just has air bubbles blown through it from a pump that's safely above ground in a nice dry box.

 

[Ivor Windybottom]

I still don't understand how the poop magically goes upwards though.

 

[d438a1]

Yeah it still seems to work and was serviced recently. So I guess will see what BC says on Friday. I agree ideally an IC would be best, but means a lot more digging and pumping to get proper access

 

[Ivor Windybottom]

It may be leaking if the ground around it is waterlogged.

I'd get it emptied and see if your groundwater magically vanishes.

 

[d438a1]

Yeah it does seem coincidental. But there is zero smell from it. And I would assume if it was leaking though that the water levels would equalise, which currently they aren’t?

 

[Hugh Jaleak]

Ah OK, it's a long way down then. A Klargester by the looks of it. Does it still work?! They seem like a troublesome way of aerating the contents, ours just has air bubbles blown through it from a pump that's safely above ground in a nice dry box.

Klargester Biodisc, they were/are a popular choice for packaged treatment plants, and the bigger versions can cater for the output from several hundred people. Personally find them a simpler design than the Biotec models with the blowers, provided the drive and bearings are suitably looked after,, there is very little to go wrong with them.

This installation looks a lot deeper than the unit would normally be sited, possibly a replacement for an earlier septic tank or cesspit, so installers were governed by existing invert depths. Looks to have a pump setup for the Final Effluent, so unlikely to be leaking, if anything it could be the final effluent is finding its way back into the excavations from the soakaway.