Septic Tank vent?

[cbk]

Looking for a bit of guidance on choice of Septic Tan and whether i need a vent pipe..  I've already installed the drainage field as pic and this includes a vent pipe on plot boudary at the lowest point. 

There will also be a vent pipe on main soil stack to house.  So my question is do I also need to attach a vent pipe to the Septic Tank?  Or is there a brand of tank that will allow airflow through the tank using my existing vents?   Max occupancy will be 8 people for christmas etc. but regularly there will only be 2 people.  I think the recommended tank size would be around 3750 - 4000 litres and it needs to be a low profile type to minimise excavation as site is on shale with limited topsoil.  Any recommendations on which brand is most suitable would be much appreciated.

[joe90]

I presume you mean sewerage treatment plant? Not septic tank?. Depends on the tank instructions but my Vortex is vented by the stack pipe at the house and no additional vent at the plant.

[cbk]

Local BCO has approved a Septic Tank, so do not intend to  go down the STP route.

[nod]

2 minutes ago, cbk said:

Local BCO has approved a Septic Tank, so do not intend to  go down the STP route.

Really 

[IanR]

26 minutes ago, cbk said:

Local BCO has approved a Septic Tank, so do not intend to  go down the STP route.

 

Have you met the General Binding Rules? 

 

https://www.gov.uk/guidance/general-binding-rules-small-sewage-discharge-to-the-ground

 

It's more difficult with a Septic Tank. It comes down to whether the system and leach field is designed to British Standard BS 6297:2007.

 

What's made you go with a septic tank rather than a small treatment plant?

 

Edited to add:
Do you know that water table will never rise up to the surface in the area of the leach field, even temporarily after heavy rain? You could have raw sewage coming up to the surface if it does.

Edited July 15, 2021 by IanR

[ToughButterCup]

39 minutes ago, cbk said:

Local BCO has approved a Septic Tank, so do not intend to  go down the STP route.

 

Ya wot?

Have you got written evidence of that? Because if you have I have a strong feeling that such approval could well be considered unprofessional. I think it highly likely that the EA would disapprove.

I really hope I'm wrong.

[jack]

Discharging sewage onto a slate base with minimal topsoil cover? I suppose your garden will grow well!

[saveasteading]

The rules re septic tank discharge are rightly more onerous, but there is no reason why the further digestion should not occur in the drainage beds, which are larger anyway.

However my own preference is to use a more sophisticated treatment tank. It is basically a septic tank with more chambers and bubbles.

They are not that much more expensive if you shop around. Of course there is the running cost of electricity, but against that, there is much better digestion and less frequent need to de-sludge.

And 20% less soakaway to build, and reduced risk of problems if the tank gets heavy use at any time.

[IanR]

41 minutes ago, saveasteading said:

And 20% less soakaway to build,

 

Or discharge directly to a water course (ditch, river etc.) and do away with the drainage field altogether.

[cbk]

1 hour ago, IanR said:

What's made you go with a septic tank rather than a small treatment plant?

Cost mainly and I've heard they can be noisy.

[IanR]

3 minutes ago, cbk said:

Cost mainly and I've heard they can be noisy.

My 10 person treatment plant (Ensign 10 from Marsh) was under £2K. Not noisy at all, I have to bend down towards the man hole to hear the pump and check it's still running.

Edited July 15, 2021 by IanR

[ToughButterCup]

17 minutes ago, cbk said:

... I've heard they can be noisy.

 

Mine is: but I installed it in (what became) someone else's garden. Oh dear, never mind, what a shame.

Couldn't make it up could ya?

 

[ToughButterCup]

23 minutes ago, IanR said:

... I have to bend down towards the man hole to hear the pump and check it's still running.

 

'S all a big plot to help you fall in and go for a swim..........

[IanR]

3 minutes ago, ToughButterCup said:

 

Mine is: but I installed it in (what became) someone else's garden.

 

Mines only got an air pump, what makes the noise on yours? Is it one of those fancy Klargesters with all the moving parts to justify the premium price?

[saveasteading]

There are some that have a big wheel sploshing round.

Most just have an air pump, like in a goldfish tank, to keep the contents moving and break the surface.

if there is any noise it will likely be a buzz from a loose support..

 

Have used Marsh Industries in the past, because they are real and will speak to you.

I especially liked that their tanks are shallow. This makes it very much easier and safer to install, without so much worry of hole collapse. 

I see that hydroclear now does shallow ones too, also at around £2,000. they include a telescopic shaft to the cover which i will be looking into.

 

Septic tank maybe £700 cheaper? 

 

Does anybody know if a septic tank requires an outlet inspection chamber, as for treatment tank? Can't see why it should not.

 

 

[PeterW]

2 hours ago, saveasteading said:

Does anybody know if a septic tank requires an outlet inspection chamber, as for treatment tank? Can't see why it should not.

No - the reason is the leach field is a secondary treatment location unlike a soakaway for a treatment tank which releases water of much higher quality. 

[saveasteading]

I thought the tank was so that a test of quality could be taken, and so that should apply to both.

The liquid after a treatment tank is going to be much better quality than from a septic tank. 

 

However, I can see that will matter even more if discharging to water course.

OR, can I use a leach field for a treatment tank, instead of a soakaway, and avoid the test chamber? That will surely  be the best of all, in dealing with any occasional overload.

[saveasteading]

Currently reading all the rules, in both the Scottish and England and Wales versions.

 

I see that both septic tanks and package treatment plants  needs sampling and inspection access at both inlet and outlet.

 

see Document H2 , clause 1.23

 

This then refers to H1, 2.48 which implies that an ordinary inspection chamber suffices. result!   or result?

 

But the Scottish document requires this. Therefore it is possible that this is also expected in England and Wales, and they are still available to buy as an expensive (£300) 'thing'.