Surface Water Drainage - Options?

[Nethermoor]

My initial drawings were all done based on SuDS with two soakaways and went through planning fine with no comments from planners or Yorkshire Water.

 

We then did a site investigation, day 1 was soil samples and coal mining and day 2 we were going to do a percolation test.  After looking at the window samples the geologist (very experienced) said there was no point doing a percolation test as he could see from the soil build up that soakaways wouldn't work (clay and mudstone).

 

From there we presumed (naively) that we would be able to do a combined connection to the sewer.  We knew there was one in the road and that quite a few neighbours discharged combined into it so didn't foresee any issue.  To be able to apply for a connection on the Section 106 form I had to purchase a sewer map (attached).  This revealed the sewer in the road is only 150mm diameter and foul only.

 

Anyway, I tried to apply for combined with my ground report from the geologist stating that as the strata is impermeable soakaways will not work, and a supporting document explaining that we had intended soakaways originally but having done a site investigation, had to change course.  Yorkshire Water promptly rejected the application, saying I could only connect foul:

 

Unfortunately, your application has been rejected pending resolution of the following issues:

1.  At planning you proposed to discharge of surface water into a soak away and the plan that was approved shows surface water into a soak away.
2.  Yorkshire Water have no combined sewers in the area. Our records show there is a foul only sewer in the highway. Surface Water is NOT allowed to discharge to a foul only sewer.
3.  Please supply a new drainage layout plan showing foul only discharging to the public foul sewer.

 

So...what are my options now?  I've asked architect and engineer but no-one seems to be very sure, guessing a few on here have been in similar situations before?

 

• Work with Yorkshire Water to see if they could accept surface water with an attenuation tank or similar?  And explain why some neighbours have combined connections into the sewer, plus others not shown on the map...
• See if I can drain surface water into highways drainage?
• Do a percolation test and hope oversized soakaway/s will work?  There's space in the front drive to fit one in within guidelines (5m from house, 2.5m from boundary)
• Lay a pipe to the nearest watercourse (350m across neighbours land and a private lane)?

19-003-10-H Proposed Site Plan-[A1].pdf CAS-02751-M3D2F6_Final.pdf

[Temp]

Look at old maps/photos. Find out if the highway drainage is a "Piped Ditch". Its possible that years ago there was an open ditch that your land drained into. This was is common in the countryside. When the road was made up or widened they frequently put pipes in the ditch and tarmac over the top.

 

Soakaways don't work on our plot so we proposed a rainwater recycling tank with overflow into the piped ditch under they highway verge. That was accepted even though its only used for garden watering and it's just a big collecting tank not a storm surge attenuation tank. I believe you can now get rainwater recycling tanks that provide some storm surge attenuation as well so they don't immediately overflow if it rains when they are full.

 

If percolation test shows soakaways would need to be very big.. it might be possible to build what you can on site and then use the gravel surrounding your foul sewer as a kind of long thin extra soakaway that just happens to run off site and down the road.  You would need to chuck in an extra perforated pipe after they have inspected your sewer connection and gone away as I don't think it's allowed.

 

 

 

[ProDave]

In spite of what your expert says, I would do those percolation tests.  Until you do, anything you do is guessing.

 

If the land does not drain at all, then when it rains it will become a paddy field.  So it must drain to some extent, just probably rather slowly.

 

And why consider the soakaway under the front?  You have more area under the back garden so to me that is the obvious place to put it.  Or perhaps both if you need a really large area.

[joe90]

Our land is clay and drains very slowly (actually I think it’s evaporation not drainage!), our BC asked for a soakaway but I pointed him at the solid yellow clay and told him I wanted to pipe it into the existing ditch which went into a road drain (which is where any rain previously ends up ) and he agreed. I didn’t need this for planning .

[Dreadnaught]

We have a storm drain nearby but still had to opt for a green roof to comply with our SUDS requirements. The requirements limited discharge in a bad storm to 2.8 l/s and prevented the first 5mm of any rain event entering the storm drain. I had to hire an engineer to do the discharge calculations to make the planners happy.

 

Unlikely but could adding a green roof be part of a solution for you?

[Nethermoor]

Thanks all, can't find any evidence on the old maps of any ditches but there must be some sort of highway drainage to explore.

 

I think you are right, I can't really avoid a percolation test so may as well get on with it.

 

14 hours ago, ProDave said:

And why consider the soakaway under the front?  You have more area under the back garden so to me that is the obvious place to put it.  Or perhaps both if you need a really large area.

Only reason was the levels, the drive is sloping away from FFL whereas the garden is approx 1m higher, but yes may well have to have two.

 

14 hours ago, ProDave said:

If the land does not drain at all, then when it rains it will become a paddy field.  So it must drain to some extent, just probably rather slowly.

Yes, there must be some drainage as it was a fairly well drained field originally. 

 

I think the 'rainwater harvesting' idea @Temp @joe90 is definitely one to keep up the sleeve!

 

 

13 hours ago, Dreadnaught said:

Unlikely but could adding a green roof be part of a solution for you?

Would be quite a big divergence from the existing plans so don't think that's an option now.

 

I'll make a start with the options suggested and see where it goes...thanks

[dpmiller]

If it was originally a field, would it be worth cutting a trench to try and find existing land drains?

[Nethermoor]

15 hours ago, dpmiller said:

If it was originally a field, would it be worth cutting a trench to try and find existing land drains?

It has always been a standalone little plot as far back as records go so I don't believe it will have any, excavations for the foundations have cut into it a fair amount and haven't seen anything as yet...