Septic tank

knittingnanny1102

Bit of an unusual situation here.  Looking to buy a house which had a new treatment system installed a couple of years back, which we were very happy about.  We have now discovered that the outflow from this and clean ground water still uses the old pipework and runs through the old septic tank which is still in place, with the final discharge to a river.  I'm worried that due to the existence of the old tank the system as a whole is not compliment, and also what issues could there be with using the old tank although in theory it is only clean water passing through and just a very big drainage pipe 

WIAWSNB

As you surmise, how could the presence of the old ST still affect the outflow? Any contents would have been flushed away by now, surely, and it was probably fully emptied when the TP was installed in any case. It is now just a clean water reservoir.

Worst case would appear to be that you'd need to by-pass the ST with a length of pipe! Ok, a bit more involved, but hardly an issue, I'd have thought. 

But, like you, I am only speculating. I, personally, wouldn't be concerned, since if an issue with this setup was ever pointed out, the solution should be cheap and simple.

That fact you have a new TP is a big plus, obvs

youth_leader

I found the binding rules very complicated when I sold my house with a septic tank.  I would recommend having a 'septic tank' survey to ensure you are meeting the rules.  

mark_cycling00

As the output from the water treatment plant is pretty much drinkable, I doubt it will turn septic from going through the existing tank and pipes.

I'm not an expert but I guess it made sense to reuse the existing soak away and the treatment plant probably needed to be in a location closer to property for powerful supply etc? 

If it's recent there should be some documentation l/certification for the treatment plant that the seller might have? It's highly regulated these days. 

As said above, really lucky to be buying a place with a treatment plant instead of having the stress of trying to get an old septic tank replaced after you've moved in..

WIAWSNB

TP installations will surely come with a cert of conformity? Ask your conveyancing solicitor to provide this as part of the process.
What I'm not sure about is whether discharge is allowed into streams and rivers? No idea. Could it be that a soak away is required?
I emph - I don't know.
Edit - seems it's ok:
https://consult.defra.gov.uk/water/reform-regulatory-system-small-sewage-discharges/results/your-sewage-your-environment-leaflet-july-2015.pdf

Section62

knittingnanny1102 said:

Bit of an unusual situation here.  Looking to buy a house which had a new treatment system installed a couple of years back, which we were very happy about.  We have now discovered that the outflow from this and clean ground water still uses the old pipework and runs through the old septic tank which is still in place, with the final discharge to a river.  I'm worried that due to the existence of the old tank the system as a whole is not compliment, and also what issues could there be with using the old tank although in theory it is only clean water passing through and just a very big drainage pipe 

Usually a treatment plant is 'secondary treatment', which further treats the output of 'primary treatment' to make it suitable for discharge to a pond or watercourse.  A septic tank is 'primary treatment', so the usual setup for a retrofit is for the existing septic tank to be retained with a treatment plant added on the outflow side.  It would also be quite unusual (not very clever) to drain surface (or ground) water into a septic tank as this can cause problems with the treatment process and there is simply no need in the majority of cases for surface/ground water to need any kind of treatment before discharge.

So I'm wondering if what you've discovered as the 'old septic tank' is in fact just a chamber on the discharge pipework - in some cases a final discharge chamber was added after the primary (/and secondary) tanks to allow the discharge to be observed and/or for maintenance on the drainage field. Can you post a picture of the inside of this chamber?

I would expect there to be another chamber between the house and the treatment plant - either the original septic tank, or perhaps a new modern plastic one installed because the existing primary treatment chamber was inadequate or poorly positioned.

Edit: If the chamber is the old septic tank and someone deems this to be a problem, then either bypass it with new pipework, or perhaps more easily, just get the chamber emptied and then filled with foamed concrete up to the invert of the discharge pipe.

knittingnanny1102

Section62 said:

knittingnanny1102 said:

Bit of an unusual situation here.  Looking to buy a house which had a new treatment system installed a couple of years back, which we were very happy about.  We have now discovered that the outflow from this and clean ground water still uses the old pipework and runs through the old septic tank which is still in place, with the final discharge to a river.  I'm worried that due to the existence of the old tank the system as a whole is not compliment, and also what issues could there be with using the old tank although in theory it is only clean water passing through and just a very big drainage pipe 

Usually a treatment plant is 'secondary treatment', which further treats the output of 'primary treatment' to make it suitable for discharge to a pond or watercourse.  A septic tank is 'primary treatment', so the usual setup for a retrofit is for the existing septic tank to be retained with a treatment plant added on the outflow side.  It would also be quite unusual (not very clever) to drain surface (or ground) water into a septic tank as this can cause problems with the treatment process and there is simply no need in the majority of cases for surface/ground water to need any kind of treatment before discharge.

So I'm wondering if what you've discovered as the 'old septic tank' is in fact just a chamber on the discharge pipework - in some cases a final discharge chamber was added after the primary (/and secondary) tanks to allow the discharge to be observed and/or for maintenance on the drainage field. Can you post a picture of the inside of this chamber?

I would expect there to be another chamber between the house and the treatment plant - either the original septic tank, or perhaps a new modern plastic one installed because the existing primary treatment chamber was inadequate or poorly positioned.

Edit: If the chamber is the old septic tank and someone deems this to be a problem, then either bypass it with new pipework, or perhaps more easily, just get the chamber emptied and then filled with foamed concrete up to the invert of the discharge pipe.

It's very complicated as the original septic tank is located on a site listed as a historic monument so highly regulated and why the original septic tank is still in place.  To explain the new treatment plant is much closer to the house and is where the waste lands first.  This plant was then just connected into the old pipework so no land was disturbed.  So after treatment it flows to the old septic tank and then into the watercourse.  I suppose I was worried about what issues there could be with the old one and potential costs down the line 

WIAWSNB

knittingnanny1102 said:

Section62 said:

knittingnanny1102 said:

Bit of an unusual situation here.  Looking to buy a house which had a new treatment system installed a couple of years back, which we were very happy about.  We have now discovered that the outflow from this and clean ground water still uses the old pipework and runs through the old septic tank which is still in place, with the final discharge to a river.  I'm worried that due to the existence of the old tank the system as a whole is not compliment, and also what issues could there be with using the old tank although in theory it is only clean water passing through and just a very big drainage pipe 

Usually a treatment plant is 'secondary treatment', which further treats the output of 'primary treatment' to make it suitable for discharge to a pond or watercourse.  A septic tank is 'primary treatment', so the usual setup for a retrofit is for the existing septic tank to be retained with a treatment plant added on the outflow side.  It would also be quite unusual (not very clever) to drain surface (or ground) water into a septic tank as this can cause problems with the treatment process and there is simply no need in the majority of cases for surface/ground water to need any kind of treatment before discharge.

So I'm wondering if what you've discovered as the 'old septic tank' is in fact just a chamber on the discharge pipework - in some cases a final discharge chamber was added after the primary (/and secondary) tanks to allow the discharge to be observed and/or for maintenance on the drainage field. Can you post a picture of the inside of this chamber?

I would expect there to be another chamber between the house and the treatment plant - either the original septic tank, or perhaps a new modern plastic one installed because the existing primary treatment chamber was inadequate or poorly positioned.

Edit: If the chamber is the old septic tank and someone deems this to be a problem, then either bypass it with new pipework, or perhaps more easily, just get the chamber emptied and then filled with foamed concrete up to the invert of the discharge pipe.

It's very complicated as the original septic tank is located on a site listed as a historic monument so highly regulated and why the original septic tank is still in place.  To explain the new treatment plant is much closer to the house and is where the waste lands first.  This plant was then just connected into the old pipework so no land was disturbed.  So after treatment it flows to the old septic tank and then into the watercourse.  I suppose I was worried about what issues there could be with the old one and potential costs down the line 

If you had to, how hard would it be to run an outlet pipe from your TP direct to the river, all within your land? Ie, what is likely to be the very worst case scenario?
(Although, most likely, you'll have gained an easement to maintain the current course).
The standard solution in such situations is for the vendor to provide an indemnity policy to cover the wcs.

Section62

knittingnanny1102 said:

Section62 said:

knittingnanny1102 said:

Edit: If the chamber is the old septic tank and someone deems this to be a problem, then either bypass it with new pipework, or perhaps more easily, just get the chamber emptied and then filled with foamed concrete up to the invert of the discharge pipe.

It's very complicated as the original septic tank is located on a site listed as a historic monument so highly regulated and why the original septic tank is still in place.  To explain the new treatment plant is much closer to the house and is where the waste lands first.  This plant was then just connected into the old pipework so no land was disturbed.  So after treatment it flows to the old septic tank and then into the watercourse.  I suppose I was worried about what issues there could be with the old one and potential costs down the line 

The site of a historic monument would be good reason to do things differently

I'd guess consent to re-route the discharge pipe might be hard to get, but as above, if the old septic tank is deemed to be a problem* then it would likely be feasible (subject to consent) to get the chamber below pipe invert level to be filled with foamed concrete - in effect converting the septic tank into a plain inspection chamber.

*The only way I could see it being a problem (other than collapse) is if the 'sump' effect of the septic tank allowed solids to accumulate.  Technically the discharge effluent should have a very low level of suspended solids, which within moving water (a pipe or open channel, like a ditch or river) should remain suspended.  But in a large chamber where the volume of 'static' water is large relative to the flow then it is possible for some of the solids to be deposited.  If these are 'organic' (as they would be from a foul water system) there's a risk of the accumulated sludge generating problematic decomposition products, or having (some of) the sludge washed out of the chamber as a result of heavy rain.

But given the status of the site I guess it would be unlikely the details of the installation weren't checked carefully and approved by all who needed to approve it.

knittingnanny1102

WIAWSNB said:

knittingnanny1102 said:

Section62 said:

knittingnanny1102 said:

Bit of an unusual situation here.  Looking to buy a house which had a new treatment system installed a couple of years back, which we were very happy about.  We have now discovered that the outflow from this and clean ground water still uses the old pipework and runs through the old septic tank which is still in place, with the final discharge to a river.  I'm worried that due to the existence of the old tank the system as a whole is not compliment, and also what issues could there be with using the old tank although in theory it is only clean water passing through and just a very big drainage pipe 

Usually a treatment plant is 'secondary treatment', which further treats the output of 'primary treatment' to make it suitable for discharge to a pond or watercourse.  A septic tank is 'primary treatment', so the usual setup for a retrofit is for the existing septic tank to be retained with a treatment plant added on the outflow side.  It would also be quite unusual (not very clever) to drain surface (or ground) water into a septic tank as this can cause problems with the treatment process and there is simply no need in the majority of cases for surface/ground water to need any kind of treatment before discharge.

So I'm wondering if what you've discovered as the 'old septic tank' is in fact just a chamber on the discharge pipework - in some cases a final discharge chamber was added after the primary (/and secondary) tanks to allow the discharge to be observed and/or for maintenance on the drainage field. Can you post a picture of the inside of this chamber?

I would expect there to be another chamber between the house and the treatment plant - either the original septic tank, or perhaps a new modern plastic one installed because the existing primary treatment chamber was inadequate or poorly positioned.

Edit: If the chamber is the old septic tank and someone deems this to be a problem, then either bypass it with new pipework, or perhaps more easily, just get the chamber emptied and then filled with foamed concrete up to the invert of the discharge pipe.

It's very complicated as the original septic tank is located on a site listed as a historic monument so highly regulated and why the original septic tank is still in place.  To explain the new treatment plant is much closer to the house and is where the waste lands first.  This plant was then just connected into the old pipework so no land was disturbed.  So after treatment it flows to the old septic tank and then into the watercourse.  I suppose I was worried about what issues there could be with the old one and potential costs down the line 

If you had to, how hard would it be to run an outlet pipe from your TP direct to the river, all within your land? Ie, what is likely to be the very worst case scenario?
(Although, most likely, you'll have gained an easement to maintain the current course).
The standard solution in such situations is for the vendor to provide an indemnity policy to cover the wcs.

Without an archeological survey and archeologist present quite difficult, but I appreciate the worst case scenario.  I did not think you could move the drainage point by more than 10m with out a whole pile of additional measures 

knittingnanny1102

WIAWSNB said:

As you surmise, how could the presence of the old ST still affect the outflow? Any contents would have been flushed away by now, surely, and it was probably fully emptied when the TP was installed in any case. It is now just a clean water reservoir.

Worst case would appear to be that you'd need to by-pass the ST with a length of pipe! Ok, a bit more involved, but hardly an issue, I'd have thought. 

But, like you, I am only speculating. I, personally, wouldn't be concerned, since if an issue with this setup was ever pointed out, the solution should be cheap and simple.

That fact you have a new TP is a big plus, obvs

Yes the new treatment plant is great.  Not all that easy to stick a new pipe on protected ground.. but I get your point.  I was just worried about if the old tank started to leak or collapsed in on itself or something similar