Septic Tank Design

[mousetarget]

Does anyone recognise this design of Septic Tank system? - I've recently moved to a new home and can't find anywhere with a design like this.

 

The waste pipe runs from the house to the bottom of a very deep, 20ft - 30ft concrete shaft, the water and waste then rises to the top (about half way up is a macerator which can be turned on) and there is a plastic pipe at the top which then takes the excess into the septic tank. I've been told that the builder who put it in also connected it in such a way to allow rainwater to access the chamber which I believe is not recommended. The septic tank is then connected to a drainage field in the garden.

 

I've always understood waste pipes connect to the top of a septic tank, and then the solids can drop to the bottom, the waste pipe from the house connects to the bottom on this shaft which confuses me.

 

See attached rough sketch, has anyone seen anything like this before? The system works fine but just want to understand it more?

[ProDave]

I suspect what you are trying to depict is a pumped system.

 

If the septic tank is higher than the invert level of the house drainage, it is draining into a small holding tank where a pump operating on a float switch will be pumping raw sewage up to the septic tank.

 

It is not necessarily a macerator but a pump capable of pumping solds.

 

I would have expected the input pipe to enter the top though and the holding tank not to be especially deep.  And no rainwater involved.

[nod]

The one we removed from our plot had been in twelve years and was ver similar to yours 

It had two 5 mtr shafts about 6 mtrs apart made up of concrete sewer sections Then a plastic tank 

[Cpd]

15 hours ago, mousetarget said:

I've been told that the builder who put it in also connected it in such a way to allow rainwater to access the chamber which I believe is not recommended.

from what I remember your right that you don't want rainwater going into your septic tank, I guess it puts to much flow through it and causes problems with the leach field but I am not sure About specific reason..... 

[mousetarget]

Thanks for the replies.

 

If indeed my drainage field cannot cope with the amount of water passing through the system, because of rainwater going in, what could be a possible solution and how expensive would it be?

 

Would it be just a case of capturing the water coming off the house roof in water butts so it doesn't enter the soakaway system which leads to the septic tank?, a bit of a pain having to empty them all the time though?

 

[Triassic]

10 minutes ago, mousetarget said:

Thanks for the replies.

 

If indeed my drainage field cannot cope with the amount of water passing through the system, because of rainwater going in, what could be a possible solution and how expensive would it be?

 

Would it be just a case of capturing the water coming off the house roof in water butts so it doesn't enter the soakaway system which leads to the septic tank?, a bit of a pain having to empty them all the time though?

 

Just divert the rainwater from the roof to a different soak away, job done.

 

https://www.eden.gov.uk/planning-and-building/building-control/building-control-guidance-notes/rainwater-soakaway-design-guidance/

 

 

Edited July 12, 2020 by Triassic