Surface water sewer map?

[Drellingore]

Any ideas how to get details on surface water sewer systems, particularly their layout and any infiltration?

 

It turns out that a previous tenant of my plot had a "land drain" installed that leads to the surface water sewer that exists alongside an adjacent road. Local folklore has it that this surface water sewer infiltrates under another field (not under my plot).

 

I've been looking at various domestic sewage options (it's complicated: groundwater source protection zone 1 means I need an Environment Agency permit), and was wondering if I can make use of this drain, if my discharge is clean enough. No doubt the EA will want to know where this surface water sewer discharges to if I'm going to use it.

 

I tried looking at the asset map of the water company that handles foul sewage in the area, but they didn't have anything on record.

 

This left me with a couple of questions:

 

• Are surface water sewers recorded like foul sewers?
• Who owns them - the water companies, Highways Agency, or someone else?

 

[Dave Jones]

https://www.digdat.co.uk/

 

can buy maps from here, £15

[Drellingore]

2 minutes ago, Dave Jones said:

https://www.digdat.co.uk/

 

can buy maps from here, £15

 

Cool, thanks for the suggestion. In that case, there's nothing on record, as it's the same system that Southern Water referred me to. How curious! Any ideas how to track down the owner in these circumstances?

[Dave Jones]

land drains on the plot belong to you, wouldn't worry about them. If you do come across them during excavations you can always reconnect and lintel over or just ignore them if they are dry/blocked.

[Drellingore]

Ta, it's the surface water sewer that our land drain connects to that I need to find out more about (who owns it, can I discharge to it, where does it discharge, etcetera).

[Dave Jones]

3 hours ago, Drellingore said:

Ta, it's the surface water sewer that our land drain connects to that I need to find out more about (who owns it, can I discharge to it, where does it discharge, etcetera).

 

cant you use a soakaway ?

[Drellingore]

7 minutes ago, Dave Jones said:

cant you use a soakaway ?

 

No, this is treated domestic sewage, and so would require a drainage field/mound rather than a soakaway. The reason I'm looking into use of this land drain that connects to a surface water sewer is because we're struggling to fit the drainage field somewhere sensible - we're currently looking at something 111m2 in total.

[Dave Jones]

pretty sure you cant put sewer into storm drains. cant you get mains connection ?

[Drellingore]

9 minutes ago, Dave Jones said:

cant you get mains connection ?

No, it'll cost £1.6m.

[ProDave]

5 hours ago, Drellingore said:

 

No, this is treated domestic sewage, and so would require a drainage field/mound rather than a soakaway. The reason I'm looking into use of this land drain that connects to a surface water sewer is because we're struggling to fit the drainage field somewhere sensible - we're currently looking at something 111m2 in total.

That's a big drainage area.  Our previous house required 85 square metres and that was a 5 bedroom house with slow draining land.

 

Have you started to look at alternatives like composting toilets?

[Kelvin]

6 hours ago, Drellingore said:

 

No, this is treated domestic sewage, and so would require a drainage field/mound rather than a soakaway. The reason I'm looking into use of this land drain that connects to a surface water sewer is because we're struggling to fit the drainage field somewhere sensible - we're currently looking at something 111m2 in total.

Sure but why can’t you install a sewerage treatment plant? Our soakaway is 18m² 

[Temp]

On 20/02/2023 at 13:54, Drellingore said:

It turns out that a previous tenant of my plot had a "land drain" installed that leads to the surface water sewer that exists alongside an adjacent road

 

It might be what we have. They call them piped ditches. Years ago it there might have been a field side ditch which your land drained into. It might even have been your responsibility to keep it clear. Then when the road was tarmaced or widened they put a pipe in it, fill and tarmac over the top. In some cases these are indistinguishable from regular road drains. 

 

In our case soakaways wouldn't work and so when we came to discharge our planning condition we proposed discharging surface water into this piped ditch. They asked Highways or the EA (I forget which) who responded saying "They wouldn't want to make flooding further down the hill worse". We responded by proposing a rainwater recycling tank with the overflow going into this piped ditch. This was approved by the planners without further consultation. Note ours is just a recycling tank not a storm surge attenuation tank like it really should be.

[saveasteading]

2 hours ago, Kelvin said:

Our soakaway is 18m²

That may be plenty in practice, with permeable ground, but the formula requires much more. I think that bcos just accept that ig looks enough.

[Gus Potter]

On 20/02/2023 at 13:54, Drellingore said:

Any ideas how to get details on surface water sewer systems, particularly their layout and any infiltration?

 

It turns out that a previous tenant of my plot had a "land drain" installed that leads to the surface water sewer that exists alongside an adjacent road. Local folklore has it that this surface water sewer infiltrates under another field (not under my plot).

 

I've been looking at various domestic sewage options (it's complicated: groundwater source protection zone 1 means I need an Environment Agency permit), and was wondering if I can make use of this drain, if my discharge is clean enough. No doubt the EA will want to know where this surface water sewer discharges to if I'm going to use it.

 

I tried looking at the asset map of the water company that handles foul sewage in the area, but they didn't have anything on record.

 

This left me with a couple of questions:

 

• Are surface water sewers recorded like foul sewers?
• Who owns them - the water companies, Highways Agency, or someone else?

 

 

I'm a bit confused as you are jumping about a bit.

 

I'll be happy to chip in but can you repost separating the surface water from the foul water. It seems to me that they are two different things?

 

If you are in an EA Zone 1 that is to do with your foul water.. surface water is a completely different animal.

 

Your starting point here is to understand your site the size of the house and the plot size it sits on.. and that gives you some figures to start with.

 

You'll maybe need to put in a bit of legwork here but may well save you in the long run.

 

If you want a good answer from BH that could save you money then you need to give more info.

 

 

 

 

 

 

 

 

 

[Drellingore]

13 hours ago, ProDave said:

That's a big drainage area.  Our previous house required 85 square metres and that was a 5 bedroom house with slow draining land.

 

Have you started to look at alternatives like composting toilets?

 

Yeah, it is. Current plans include a second building as as holiday let, but we're beginning to reconsider that (the missus really wants a natural swimming pool instead). The infiltration area is only 47sqm or so, but the total area needed is much larger.

 

We actually have a composting toilet on site (the most complicated thing we've built so far!) so we can spend time there. However, building regs and the like don't seem to take any account of how many toilets are composting. It's all based on the number of bedrooms, and we'd still have other domestic discharge to deal with.

 

12 hours ago, Kelvin said:

Sure but why can’t you install a sewerage treatment plant? Our soakaway is 18m² 

 

Approved Document H2 says that drainage fields are still required for packaged treatment plants. We're actually speccing a PTP with a further tertiary treatment system. I'd be interested if you could point me in the direction of any legislation that says that drainage fields aren't necessary for PTPs.

 

11 hours ago, Temp said:

It might be what we have. They call them piped ditches. Years ago it there might have been a field side ditch which your land drained into. It might even have been your responsibility to keep it clear. Then when the road was tarmaced or widened they put a pipe in it, fill and tarmac over the top. In some cases these are indistinguishable from regular road drains. 

 

Ooh, that's really, really interesting. That might represent a much simpler solution! I wonder how I can find out more about what the EA define a 'ditch' as.

 

8 hours ago, Gus Potter said:

I'm a bit confused as you are jumping about a bit.

 

I'll be happy to chip in but can you repost separating the surface water from the foul water. It seems to me that they are two different things?

 

Apologies if I wasn't clear. I need to discharge domestic sewage. There isn't enough space to comfortably fit the required drainage field. There is a surface water sewer (storm drain) adjacent to the property. There is a "land drain" (previous farmer owner's words) that connects my property to the surface water sewer. Our PTP system will output extremely clean discharge (should be 99+% filtration efficiency). Hence I'm interested in finding out if the EA will allow such a clean discharge to a surface water sewer, even if that isn't the norm. I understand that foul sewers and surface water sewers are different things.

 

8 hours ago, Gus Potter said:

Your starting point here is to understand your site the size of the house and the plot size it sits on.. and that gives you some figures to start with.

 

You'll maybe need to put in a bit of legwork here but may well save you in the long run.

 

If you want a good answer from BH that could save you money then you need to give more info.

 

Thanks, already done all that. Plot is 5 acres (although 3 of those are uphill) but shape is more important. Current design (which is not final) is 12PE. Size of drainage field required is given earlier in this post.

[Kelvin]

See here. The bit of relevance to you is near the bottom where it talks about how legislation has not caught up with modern package treatment plant performance but that building control etc will often take a pragmatic approach. If a drainage field must always be installed with a treatment plant then the vast majority of plots wouldn’t have the space for one. Obviously your requirement is larger than average at 12PE. If this is because of the holiday let side of things then the composting toilet suggestion seems like a reasonable approach. 
 

https://www.homeseptic.co.uk/drainage-field-size-calculation-and-design/

[Drellingore]

7 minutes ago, Kelvin said:

building control etc will often take a pragmatic approach

 

Thanks. That's a bit too woolly for my liking when there's quite a lot of money at stake (a cess pool that large will cost about £18-25k and might cost £4k/year to empty), so I need to deal with something more certain - BS6297:2007+A1:2008 seems to be the most authoritative source. I need to apply for an Environment Agency permit, so hopefully as part of that they'll say "cripes, you don't need a drainage field, here's a permit" and then I can wave that at building control later down the line.

[Drellingore]

@Temp that's been a really interesting lead to follow. I've gotten on to National Highways, who don't own it. They put me through to Kent County Council Highways, who have those gullies on their asset register - which explains why Southern Water didn't have them on record. They're going to get back to me to clarify whether it's basically a ditch, or part of some more complex system with proper pipes and stuff. If it's a ditch, that could be a massive win.

[Kelvin]

Have you actually spoken to building control though and asked them? 

[Drellingore]

5 minutes ago, Kelvin said:

Have you actually spoken to building control though and asked them? 

 

Emailed, had no response. Based on the fact that we haven't got planning permission approved yet, I assumed that BC would tell me to sod off without something much more specific. Besides, the Environment Agency's opinion is more important here, as I need a permit from them owing to being groundwater source protection zone 1.

[saveasteading]

7 hours ago, Drellingore said:

any legislation that says that drainage fields aren't necessary for PTPs.

It simply allows 25% reduction in area. Silly but fact.  I expect this is why bcos overlook undersized drainage fields, as it looks OK to them.

 

7 hours ago, Drellingore said:

the EA define a 'ditch' as

I doubt if they do. But the relevant difference would be a sealed pipe, to carry water,  or one with open joints, to allow ingress/egress as well as to carry it.

 

I suggest a fomal proposal is presented, with drawings and support for the arguments. The bco will send it to the EA and perhaps never get a response.

 

I might include the argument re the composting toilet, although they could reasonably argue that it might go unused, by future owners if not you.

[Temp]

I expect you've seen this on new discharges after changes in 2015..

 

https://www.direct-drainage.co.uk/blogs/useful-information-faqs/environment-agency-general-building-rules-for-septic-tanks-sewage-treatment-systems

 

Quote

 

New discharges are not allowed to a ditch or a surface water that does not contain flowing water throughout the whole year (unless there is a drought or an unusually long period of dry weather).

 

New discharges to watercourses that seasonally dry up are not allowed under the general binding rules, nor are discharges to enclosed lakes or ponds.

 

 

 

[crooksey]

22 hours ago, Drellingore said:

 

Thanks. That's a bit too woolly for my liking when there's quite a lot of money at stake (a cess pool that large will cost about £18-25k and might cost £4k/year to empty), so I need to deal with something more certain - BS6297:2007+A1:2008 seems to be the most authoritative source. I need to apply for an Environment Agency permit, so hopefully as part of that they'll say "cripes, you don't need a drainage field, here's a permit" and then I can wave that at building control later down the line.

 

The local council and the EA actively try and discourage cespool installs, they are terrible for the environment with all the emptying they need. They will be much more receptive than you think, I don't mean to be rude but you are going about this all wrong. Usually before/when you apply for planning, you include detailed proposed foul drainage plans. I don't see how you plan to get planning without having this done first and frankly your planning agent needs talking to as they will know this.

 

Get proper percolation testing done

Get a drainage engineer to design your system

Submit a detailed drainage proposal with your planning application.

 

As part of the application process, the local council will review your drainage proposal and basically say yes or no. If they say yes and it has been designed by a reputable drainage engineer, then building control will have no issue with it. Then you can take the building control and planning approval to the EA for the final confirmation. This is how it usually works with new build/one off homes, all be it the EA is rarely involved but they will want the planning approved with a drainage design approved by the council drainage officer. 

[ToughButterCup]

22 minutes ago, crooksey said:

 

The local council and the EA actively try and discourage cespool installs, they are terrible for the environment with all the emptying they need. ...

 

The installation of a cesspit will require Planning Permission, and therefore Building Control regulation.

@crooksey is being diplomatic : any cesspit is highly unlikely to get PP.

[Kelvin]

@crooksey Yes this is how we did it. I organised a percolation test as part of the due diligence when buying the plot. This determined the ground suitability for a soakaway, the size and where to locate it. Then as part of the planning application we had a rough drainage design done. The SE did another detailed drainage design as part of the warrant application. Ours was complicated by the fact that only one area was really suitable for the soakaway, there are two boreholes nearby, and we have a running water course through the bottom of the plot. Fortunately the ideal soakaway location is perfectly cantered to meet all the distance regulations.