Treatment Plant discharge to inundation pond (rain water open soak away pond)

[cheekmonkey]

My planning has a stipulation in wildlife mitigation to build an inundation pond to take some rainwater from one roof face & excess from other face (majority to be held in storage tank).

 

We will need to have treatment plant to handle sewerage waste as no mains here.

 

There is no water course to discharge to

 

My thinking was to discharge to the inundation pond rather than a drainage field for 2 reasons.

 

1. The pond needs to be build anyway & needs to be in the low point of the plot (where the barn is) & will be about spot on in terms of distances from boundary/building etc

2. The drainage field would need to be built uphill if we did one due to constraints in space & why have two things doing a similar job

 

I have asked about & the response is generally "you cant do it" BUT if I read the guidance it reads to me that you can: #rule 21 https://www.gov.uk/guidance/general-binding-rules-small-sewage-discharge-to-a-surface-water

 

In my head the pond is NOT lined so does not meet all of the following. It is in effect a big open drainage field.

 

Does anyone agree or have experience? Will I need to still do Percolation tests if it's usable?  (planning stipulates approx 50m2 pond)

================================

_{You cannot meet the general binding rules if you have a new discharge to an enclosed lake or pond. This means a lake or pond in which all of the following apply:}

• _{it contains water throughout the year, other than in extreme weather conditions}
• _{it does not have an outfall that connects it to a watercourse, or has an outfall that only discharges in extreme weather conditions}
• _{it is sealed or lined to prevent water draining into the ground or soaking into the surrounding soil}

_{You do not need a permit to discharge to an enclosed lake or pond. But you must use appropriate pollution prevention measures to make sure your discharge does not cause pollution.}

 

 

 

[Drellingore]

I'm not sure if I follow your line of thinking entirely, but rule #19 says that you can't meet the General Binding Rules if the water you're discharging to doesn't have flow:

 

Quote

 

Make sure the surface water has flow (rule 19)

You cannot meet the general binding rules if you have a new discharge to:

• a ditch or a surface water that does not contain flowing water throughout the year, unless there is a drought or an unusually long period of dry weather
• watercourses that seasonally dry up

 

So I take that to mean that your inundation pond wouldn't an acceptable watercourse that you could discharge to. Apologies if I've misunderstood anything. Also - I have no relevant experience!

[cheekmonkey]

2 hours ago, Drellingore said:

I'm not sure if I follow your line of thinking entirely, but rule #19 says that you can't meet the General Binding Rules if the water you're discharging to doesn't have flow:

 

 

So I take that to mean that your inundation pond wouldn't an acceptable watercourse that you could discharge to. Apologies if I've misunderstood anything. Also - I have no relevant experience!

 

 

Agree but point 21 is a bit contradictory - i guess fishing for someone who might have done something similar - i figured i can submit to building control as the pond & see what they say.

[Drellingore]

6 minutes ago, cheekmonkey said:

someone who might have done something similar

 

I deffo can't help there then - best of luck!

[Jenki]

In Scotland, my BC stated the two shall not meet. I.e 50m rubble drain for treatment plant.

Separate soakaway for top water.

 

[saveasteading]

20 hours ago, Jenki said:

In Scotland, my BC stated the two shall not meet. I.e 50m rubble drain for treatment plant.

Yes it is a clear rule. I think this is a carryover from before treatment plants. Ie when all drainage fields were still treating sewage, which shouldn't be washed away.

I'm certain I could persuade a knowledgeable bco to allow them to be combined but it would probably have to go to SEPA  (or EA in England) and I couldn't be bothered. Plus we have the space, so would have had to justify that too (other than cost).

[saveasteading]

21 hours ago, Jenki said:

In Scotland, my BC stated the two shall not meet. I.e 50m rubble drain for treatment plant.

Yes it is a clear rule. I think this is a carryover from before treatment plants. Ie when all drainage fields were still treating sewage, which shouldn't be washed away.

I'm certain I could persuade a knowledgeable bco to allow them to be combined but it would probably have to go to SEPA  (or EA in England) and I couldn't be bothered. Plus we have the space, so would have had to justify that too (other than cost).

[saveasteading]

Will I need to still do Percolation tests if it's usable?  (planning stipulates approx 50m2 pond)

 

Why don't you? It is very easy to do, and you will understand your options better.

it requires a spade, a bucket (and water source) a watch and an hour of your own time. If more than an hour then there is a percolation challenge.

 

you should not let your sewage anywhere near the pond.

 

I'm not sure I understand your problem? Is it that you don't want to do it, or there are technical issues or a lack of space?

For example, how much rainwater can it hold, and where does it go if it overflows?

 

 

[cheekmonkey]

1 hour ago, saveasteading said:

I'm not sure I understand your problem? Is it that you don't want to do it, or there are technical issues or a lack of space?

 

Why make a drainage field & a pond if you can just make one thing (the pond). Less time / Less money / Less space / Less mess.

 

I'll do some perc tests, but more than an hours work if you go to correct depths but I get the point, might as well have that info. 👍

 

  

1 hour ago, saveasteading said:

you should not let your sewage anywhere near the pond.

 

 

The sewage won't be but the outlet water would. If that's good enough for a river it's good enough for a pond? Or is there another issue you're thinking?

Edited January 25, 2023 by cheekmonkey

[ToughButterCup]

On 24/01/2023 at 12:54, cheekmonkey said:

My planning has a stipulation in wildlife mitigation to build an inundation pond to take some rainwater from one roof face & excess from other face (majority to be held in storage tank).

....

 

Thats not clear: and stipulations need to be clear . What's a majority? What size does the pond have to be? Can the pond size be halved and the other half into a drainage field?

 

Are you in Scotland? Because if you aren't, I'll bet @SteamyTea's best carving knife that the BCOs in England won't give a CockWombles Tadger about those  conditions. Ours - looking at my request - at our Inundation Pond said

 

"Oooooo, hmmm " And walked off

[cheekmonkey]

3 minutes ago, ToughButterCup said:

 

Thats not clear: and stipulations need to be clear . What's a majority? What size does the pond have to be? Can the pond size be halved and the other half into a drainage field?

 

Are you in Scotland? Because if you aren't, I'll bet @SteamyTea's best carving knife that the BCOs in England won't give a CockWombles Tadger about those  conditions. Ours - looking at my request - at our Inundation Pond said

 

"Oooooo, hmmm " And walked off

 LOL

 

Basically I have to implement the biodiversity plan in full as a condition of planning- the pond was in that. It takes all rain water from roof, the back face goes via storage & overflow onto the pond. In bio plan it stated min 50m2 with native planting

Have had similar experience of BCO's in England.

[saveasteading]

42 minutes ago, cheekmonkey said:

Why make a drainage field & a pond if you can just make one thing (the pond). Less time / Less money / Less space / Less mess.

OK that's clear thanks. Only rainwater should go into the pond. Any grey water, even from bath, will have detergents and body dirt in it, and a risk of bleach, none of which is nice in a pond. Would you swim in it would be a decent test. 

You will get plants and creatures, which would be great. The plants will drink some water too, and the roots may increase drainage routes. Fish drinking the water doesn't count.

The volume of water from sewage is relatively small. To avoid a huge drainage field, ask your bco if a soakaway is enough.

[crooksey]

Wildlife mitigation is always about biodiversity net gain, I imagine (and speak to your planning officer) you may be able to remove the need for a pond if you can show or implement other features to positively impact the local bio-diversity, stating that you already have plans to re-cycle the rainwater through the use of rainwater harvesting which will limit the amount of actual rain entering this pond. Alternatively you could look at something like a graf chlorine filter or a marsh ensign UV filter to treat the effluent from the plant, dump that into a 10,000l holding tank (that also takes your rain water) and then have this discharge to the pond. Whether or not this is suitable all depends on building control, my vote would be to instruct a private controller as a local council controller will just read you the regs and have no further discussion.

 

What type of soil do you have is the ultimate question here, as if you have soil suitable to take a drainage field or infiltration tunnels this will be the best bet. If you are on heavy deep clay, then don't even attempt to design yourself, commission percolation testing and system design, you may even need a borehole (to which the application can take up to 2 years to process).

 

Most firms that empty septic tanks etc also usually do an install service and will have good knowledge of local ground, give them a call and I am sure they could help.

 

Good luck.

[cheekmonkey]

22 hours ago, crooksey said:

Wildlife mitigation is always about biodiversity net gain, I imagine (and speak to your planning officer) you may be able to remove the need for a pond if you can show or implement other features to positively impact the local bio-diversity, stating that you already have plans to re-cycle the rainwater through the use of rainwater harvesting which will limit the amount of actual rain entering this pond. Alternatively you could look at something like a graf chlorine filter or a marsh ensign UV filter to treat the effluent from the plant, dump that into a 10,000l holding tank (that also takes your rain water) and then have this discharge to the pond. Whether or not this is suitable all depends on building control, my vote would be to instruct a private controller as a local council controller will just read you the regs and have no further discussion.

 

What type of soil do you have is the ultimate question here, as if you have soil suitable to take a drainage field or infiltration tunnels this will be the best bet. If you are on heavy deep clay, then don't even attempt to design yourself, commission percolation testing and system design, you may even need a borehole (to which the application can take up to 2 years to process).

 

Most firms that empty septic tanks etc also usually do an install service and will have good knowledge of local ground, give them a call and I am sure they could help.

 

Good luck.

thanks @crooksey - interesting thought on the net gain side. rain water harvesting/storage is also in the planning app. I am using a private BCO

 

we have sandy soil.  ive got one more perc test to run but circa 1.5hrs to drain the 150mm across all holes at all times (soil is very consistent & undisturbed)  I did wonder about infiltration tunnels as takes up way less space.    Ive been trying to get a few drains install people in to advise & look at it but they all just want to be told what to do & aren't interested in solving the problem or being creative with the solution

Edited February 1, 2023 by cheekmonkey

[saveasteading]

I can't see how drainage tunnels are any better than perf pipe and gravel, except they have done tests and they are 'a thing' for the bco to accept.

Borehole drains silt up over a few years and are last resort.

But you have sandy soil so lucky you. But 1.5 hours is quite slow still.*

I agree with the above...make all your rainwater drains French drains, (at negligible extra cost) and the pond will be almost dry until a big storm comes.

It is also more sustainable as you are spreading the water out.

 

* have you tried digging deeper. The top may be compressed or silted up.

[saveasteading]

22 hours ago, crooksey said:

Wildlife mitigation is always about biodiversity net gain

But reading proposals, it seldom is anything other than waffle and some bird boxes. The formal approaches give more marks for furry animals with big eyes, than for insects etc.

The best biodiversity probably comes from rotting wood and some shrubs...and a muddy, messy pond. I would use that approach next time I have to.

[Conor]

On 25/01/2023 at 15:46, cheekmonkey said:

 

The sewage won't be but the outlet water would. If that's good enough for a river it's good enough for a pond? Or is there another issue you're thinking?

 

Primary treated water effluent is high in nitrates and phosphates. Your pond will be green slimy mess in a matter of months. You need either secondary treatment to get rid of these, or a way to deal once in the environment (reed bed, percolation treatment etc.) In a river, these nitrates are naturally diluted.... but ultimately lead to the generally crap water quality in our rivers.

[saveasteading]

1 minute ago, Conor said:

Primary treated water effluent is high in nitrates and phosphates. Your pond will be green slimy mess in a matter of months

As my earlier post. Cheekbones, I was assuming you agree/accept this, otherwise my other comments are redundant.

[IanR]

On 24/01/2023 at 12:54, cheekmonkey said:

My planning has a stipulation in wildlife mitigation to build an inundation pond 

~~~~~~~~

My thinking was to discharge to the inundation pond 

 

Your inundation pond is intended, in part, to be a site for "aquatic local wildlife".

 

In England, you can't discharge within 50m of it, including your leach-field site, without a permit from the EA.

[cheekmonkey]

so i think the answer is becoming clear it's a drainage field separate to the pond as a way forward - the problem is then the pond just doesn't fit in any place that would naturally fill (level wise) so i'll need to address that 'net gain' somehow with the environment team.

 

thanks for all the input

[saveasteading]

It depends on the skills of ' the environment team'.

I'd suggest you do your own scheme to show people. Make it easy to understand. Plan drawing pluux description. Sell the plus points. Show how it deals with the regulations. And tick off all the bullet points that have been put before you.

[crooksey]

@cheekmonkey graf do great sewage plants, maybe speak to them and see if they can reccomend anyone to design a system with their tunnels.

 

I also agree with what @saveasteadinghas said, sometimes you need to dig a bit deeper to get to the "better", espically if the site has had a previous life has farmland/yard etc as it may have up to 1m in topsoil/made ground from other locations (seen it a few times).

[saveasteading]

2 hours ago, crooksey said:

may have up to 1m in topsoil/made ground 

Or cow muck, which filters through. Our ground is pure sand which drains at 17 seconds/mm  Except in the covered barn area where there was zero percolation. After 300mm of excavating manure and sand mix,  it is clean again.

 

Sheep's feet also make ground impenetrable by puddling clay, just as canals were lined.