Waste and surface water treatment

[Ktelobb]

Hi all, here’s hoping someone can come up with a solution. We are in a very tricky situation, we bought a development plot With planning permission to demolish and rebuild however in the small print of the contract it states that the vendor will not allow us to continue to use the existing drain for waste water which runs under his retained land and exits in a pond on his retained land. This has now left us in a really crappy situation where we don’t know how to get rid of our waste water for the new build, we are not on mains drains, there are no other water courses for us to drain into and we have clay soil. We are now going down the solicitor route to see if we can get him to change his mind But in the meantime I wondered if there was an alternative solution. I had heard of above ground mound soakaways? 
 

thanks

[joe90]

When you say “waste water” does that include rain water?. Yes mound fields for treatment plants do work if a bit expensive so I have heard.

[ProDave]

You could try for an above ground filter mound.  Basically a pile of expensive graded sand (I costed it at about £1000 for the sand) and the effluent is pumped to a drainage field on top of that and it percolates down through the sand into the ground below.

 

To prove that is viable you have to do a percolation test, but instead of digging a deep hole, you do the percolation test in a shallow hole at ground level.

 

All you need to know and how to do the calculations is in this book https://www.brebookshop.com/details.jsp?id=148788

 

However I objected to paying £50 for a book containing just a few actual useful pages so I went to our local library who got it on an inter library loan for me at a cost of just over £1 for the postage.

 

 

[Ktelobb]

9 minutes ago, joe90 said:

When you say “waste water” does that include rain water?. Yes mound fields for treatment plants do work if a bit expensive so I have heard.

Yes, waste water and rain water were previously going through a soakaway and then out under the vendors retained land to a pond. 

[Ktelobb]

8 minutes ago, ProDave said:

You could try for an above ground filter mound.  Basically a pile of expensive graded sand (I costed it at about £1000 for the sand) and the effluent is pumped to a drainage field on top of that and it percolates down through the sand into the ground below.

 

To prove that is viable you have to do a percolation test, but instead of digging a deep hole, you do the percolation test in a shallow hole at ground level.

 

All you need to know and how to do the calculations is in this book https://www.brebookshop.com/details.jsp?id=148788

 

However I objected to paying £50 for a book containing just a few actual useful pages so I went to our local library who got it on an inter library loan for me at a cost of just over £1 for the postage.

 

 

Thanks, we did some percolation tests for in ground soakaways and they failed due to clay soil. 

[ProDave]

13 minutes ago, Ktelobb said:

Thanks, we did some percolation tests for in ground soakaways and they failed due to clay soil. 

That's the point.  For an in ground system you typically dig a hole about a metre deep, then dig your 300mm cube hole in the bottom of that and do the percolation test.  Here at this time of year it would fill with water and stay full.

 

But for an above ground filter mound, you literally dig a 300mm cube hole right at the ground level and do a percolation test in that.  If that passes you are good to go with a filter mound system.

[ProDave]

Another option is the Puraflow filter system https://tricel.co.uk/sewage-treatment/packaged-filter-systems/

 

When I looked at that, the installation would have been excavate some of the top soil an place an area of large stones.  the puraflow crates would sit on that and the effluent would slowly filter through the crates and into the ground through the stones.

[Ktelobb]

10 minutes ago, ProDave said:

Another option is the Puraflow filter system https://tricel.co.uk/sewage-treatment/packaged-filter-systems/

 

When I looked at that, the installation would have been excavate some of the top soil an place an area of large stones.  the puraflow crates would sit on that and the effluent would slowly filter through the crates and into the ground through the stones.

Thanks for this, but does this still not need some kind of drainage field? 

[Ktelobb]

17 minutes ago, ProDave said:

That's the point.  For an in ground system you typically dig a hole about a metre deep, then dig your 300mm cube hole in the bottom of that and do the percolation test.  Here at this time of year it would fill with water and stay full.

 

But for an above ground filter mound, you literally dig a 300mm cube hole right at the ground level and do a percolation test in that.  If that passes you are good to go with a filter mound system.

Thanks for the advice, I will talk to our builder about this. 

[Oxbow16]

How chronic was the perc test failure?  And how deep was your 300mm hole when you did the test??

 

Are you discharging from a septic tank or sewage treatment plant?  

 

Ta

Edited November 1, 2020 by Oxbow16

[Ktelobb]

3 hours ago, Oxbow16 said:

How chronic was the perc test failure?  And how deep was your 300mm hole when you did the test??

 

Are you discharging from a septic tank or sewage treatment plant?  

 

Ta

We did 3 separate holes they were all about a metre deep. 
we’ll be putting in a new treatment plant. 

[ProDave]

On 29/10/2020 at 20:00, Ktelobb said:

Thanks for this, but does this still not need some kind of drainage field? 

Yes, the drainage field goes on top of the big pile of expensive sand, then you cover it with soil so you have a "hill" in your garden.

 

Alternatively, dig even deeper and see if you can find something better below your band of clay?

[Oxbow16]

21 minutes ago, Ktelobb said:

We did 3 separate holes they were all about a metre deep. 
we’ll be putting in a new treatment plant. 

 

A metre is the maximum depth to test for this...  I presume you mean a metre to the bottom of the 300mm test hole?  Or were you referring just to the main test hole?  

 

So in terms of the failure, how bad was it?  Did it take days to drain?  Weeks?  Still full now?  

 

19 minutes ago, ProDave said:

Yes, the drainage field goes on top of the big pile of expensive sand, then you cover it with soil so you have a "hill" in your garden.

 

Alternatively, dig even deeper and see if you can find something better below your band of clay?

 

I did read lots about "clay caps" and far more permeable soils beneath them.  The trouble is that for wastewater the pipe can be no lower than 700mm...  

[Ktelobb]

25 minutes ago, Oxbow16 said:

 

A metre is the maximum depth to test for this...  I presume you mean a metre to the bottom of the 300mm test hole?  Or were you referring just to the main test hole?  

 

So in terms of the failure, how bad was it?  Did it take days to drain?  Weeks?  Still full now?  

 

 

I did read lots about "clay caps" and far more permeable soils beneath them.  The trouble is that for wastewater the pipe can be no lower than 700mm...  

when we did the original holes, the weather was better than it is now and the holes did drain better obviously, we still have the holes and now they aren’t draining due to all the rain we’ve had. I think we have a solution for the waste septic water in a mound soakaway, but we still need a solution for surface water, I have just been reading about Rainactiv attenuation tanks and rainwater recycling, wondered if this was an option, but presumably we still need the surplus to run off somewhere?

[ProDave]

The surplus rainwater must soak into the ground now otherwise your site would be a pond now?

[Mr Punter]

On 29/10/2020 at 19:02, Ktelobb said:

We are now going down the solicitor route

 

I hope this is not the same solicitor who advised you on the purchase?  The seller specifically limiting your ability to connect drainage should have been very clearly communicated to you by your lawyer.  That is what they get paid for.  They have PI insurance for this sort of negligent blunder.

[SuperJohnG]

27 minutes ago, Mr Punter said:

That is what they get paid for.  They have PI insurance for this sort of negligent blunder

I'd agree. I'd be chasing solicitor here if he/she did not advise you correctly. 

[ProDave]

But if he bought the plot, knowing the option to drain into adjacent land had been blocked, and the solicitor advised him of that fact, how is the solicitor negligent?

[Temp]

Is the plot big enough to dig your own pond?

[joe90]

44 minutes ago, Temp said:

Is the plot big enough to dig your own pond?

overflow still needs to go somewhere!!,

[pauldoc]

On 01/11/2020 at 20:34, Ktelobb said:

when we did the original holes, the weather was better than it is now and the holes did drain better obviously, we still have the holes and now they aren’t draining due to all the rain we’ve had. I think we have a solution for the waste septic water in a mound soakaway, but we still need a solution for surface water, I have just been reading about Rainactiv attenuation tanks and rainwater recycling, wondered if this was an option, but presumably we still need the surplus to run off somewhere?

Hi

i am having similar issues working out the drainfield.

you mentioned you are probably going with a mound soak away now. Does this still require the same sort of size drain field that would be ‘underground’?

also have you or anyone looked into infiltration systems?

I have read a few articles these can be used when space is an issue for a drainage field. Something like this

https://www.graf-water.co.uk/wastewater-treatment/all-about-wastewater-treatment/infiltration-system-for-wastewater-treatment.html

you still have to do the required percolation tests but may be an alternative 

[joe90]

That’s ok but...........      All that's required is a soil type suitable for infiltration and a sufficient distance of at least 1 m from the groundwater level.

[pauldoc]

Why is it a ‘but’?

sorry if I’m asking a silly question but is a suitable soil type for infiltration the same as a soil requirement for a drainage field? Is the infiltration the actual water soaking away?

im asking as I have a problem with my existing soak away which wasn’t constructed properly so has failed (don’t ask!) and I need to install another and am now a little tight on space for it

 

Edited November 14, 2020 by pauldoc
Additional question

[joe90]

“But” you still need soil that will allow water to soak away, we are on solid clay but we had a ditch that we could use.

[pauldoc]

Fingers crossed I have ! Thanks for the reply