Perenial Stream existance

[dnoble]

Currently formulating a plan to deal with rainwater from 160m2 roof.

Heavy clay means soakaway probably not an option and PO seems to acknowledge this so maybe able to negotiate connection to main drain.(Also having some attenuatiuon in the form of green roof and rainwater harvesting)

There is a intermittant steam in the garden that only runs after rain and disappears into the ground 10m or so away (still in the middle of my land)

This stream isn't documented on any plans or surveys.

I wonder if I could send my roof water into this (it probably goes there any way as land house will sit on drains into it.)

My concern is whether anyone will reconise this stream as an entity. Is there a way of documenting it?

Dan

Edited September 20, 2017 by dnoble
sausage finger typos

[Jeremy Harris]

The standard'ish way to deal with this (we are on clay, too, with a stream close by) is to fit surge attenuation.  Several ways of doing this, but the idea is to slow down the release of a surge of rain water and allow it to enter the stream at a much slower rate, so reducing the risk of a flood surge downstream, or any other area.

 

In our case we didn't have room for the cheapest option, which would have been a pond with a slow leak to the stream, so had to install 20 off Aquacell crates underneath the drive.  These have created a permeable "tank" that can store up to around 4000 litres of water, and which drains away slowly from permeable soil in one corner, under the lane to the stream.   I managed to buy some crates that were surplus from a big civil engineering job (they are used a fair bit on some road drainage systems, apparently), which reduced the cost, but we still had to excavate a hole about 1.5m deep to put them in, covering them with teram membrane and connecting all the rain water drainage pipes to this.

 

In practice it works very well, with no sign of any water run off from the drive or lower edge of the site.  It wasn't cheap though, and would have cost a lot more if I'd paid full price for the crates.

Edited September 20, 2017 by JSHarris

[dnoble]

Hi Jeremy. I agree I'll need to incorporate some kind of attenuation.

Specifically though I need to know if allowed to use this stream which doesnt oficially seem to exist for the overflow

(I'd like to as would avoid me having to sent ot otherwise to main sewer)

[Jeremy Harris]

I can't see why not, but you may need clarification, and perhaps a permit to discharge, from the Environment Agency.  We cheated, because the stream is the other side of the lane, so did a percolation test in the band of porous soil where the surge tank was going to drain to.  We knew this was hydraulically connected to the stream, via the hardcore under the lane, but as far as building control were concerned as long as that area passed the perc test we were OK.

 

You may be able to make some sort of hidden porous "leak" to the stream, cover it up, then do a perc test in the area where you want to discharge your surge tank/pond.  That might get around having to jump through hoops with the EA.

[dnoble]

Thats a clever workaround.

I've spoken to the environment and they agree in principal it should be fine but agree that the stream doesn't officially exist. They also didn't know how or what the process is for getting it verified.