Soakaways: alternatives?

[Post and beam]

From my house the land slopes away to the east about 15- 20 feet downwards over about 50 metres towards farmland. We have a 3/4 acre plot. The rain water that used to fall where the house now sits never caused any issues with flooding to anyone. So my question: is it possible to just run some drain pipes from my gutters say half way down the slope and let the rainwater soak away naturally. I am trying to avoid an expensive and large soakaway if i can.

[crispy_wafer]

You'd need to run the pipes into something to allow the rainwater out, so some form of soakaway with crates, terram, and gravel should suffice.  What would you deem as expensive?  Have building control indicated anything size wise?

[JohnMo]

15 minutes ago, Post and beam said:

pipes from my gutters say half way down the slope and let the rainwater soak away naturally

I doubt building control would be happy.

 

Why does a rain water soak away from have to be big or expensive. In it's simplest form it's a hole lined with membrane a 110mm pipe has slots cut in the bottom and it's back filled with crushed rock. You don't even need crates. We ended up with 2 and they took half a day each - one man and a digger.

 

Ours before and after filling for 250m² of roof.

 

 

 

Edited Thursday at 11:24 by JohnMo

[crispy_wafer]

1 minute ago, JohnMo said:

I doubt building control would be happy.

 

Why does a rain water soak away from have to be big or expensive. In it's simplest form it's a hole lined with membrane a 110mm pipe has slots cut in the bottom and it's back filled with crushed rock. We ended up with 2 and they took half a day each - one man and a digger.

 

 

yep this, like most things, would these days cost more in labour than materials.

[ToughButterCup]

Look up the terms 'SUDS' and 'Rain Garden' . You'll find masses of stuff to help you. 

[Stratman]

I found this quite straightforward to calculate a soakaway size for early design purposes: https://www.cncbuildingcontrol.gov.uk/faqs/calculate-size-soakaway-required-extension/

 

Some of the other online calculation tools I came across look very complex and longwinded but I may have to bite the bullet later in the process.

[Post and beam]

6 hours ago, crispy_wafer said:

  Have building control indicated anything size wise?

4 metres by 3.5 metres at > 1.5 metres deep plus a silt trap.

 

4 hours ago, ToughButterCup said:

'SUDS' and 'Rain Garden' .

Will do. Thanks.

 

6 hours ago, crispy_wafer said:

What would you deem as expensive?

In excess of £8k

 

6 hours ago, JohnMo said:

it's a hole lined with membrane a 110mm pipe has slots cut in the bottom and it's back filled with crushed rock.

You cannot do that anymore. I have a huge pile of rubble that would do the trick but it has to be crates

[crispy_wafer]

34 minutes ago, Post and beam said:

n excess of £8k

Christ alive, indeed, yes, I’m sure it can be done cheaper, so what about 20m2 ish, quick search suggests 150 per m3 for crates, but i bet cheaper if bought from your local civils place. Then backfill with pea gravel, hire in a machine for a weekend.  Back of hand calcs suggest less than half your 8k, or am i being  optimistic

Edited Thursday at 18:29 by crispy_wafer

[JohnMo]

47 minutes ago, Post and beam said:

You cannot do that anymore.

Are you sure, not what building regs says!

[Post and beam]

24 minutes ago, JohnMo said:

Are you sure, not what building regs says!

JohnMo: No not sure, i trusted what i was told by BC & others.  Its worth learning how to use a digger i think.

[crispy_wafer]

22 minutes ago, Post and beam said:

Its worth learning how to use a digger i think.

Indeed, right of passage for any self builder.  Sounds like you have plenty of room to practice.  

[Post and beam]

57 minutes ago, crispy_wafer said:

Indeed, right of passage for any self builder.  Sounds like you have plenty of room to practice.  

The plot is 3/4 acre and sloping away from the house. Which is why i question the need for any soakaway. I cant see why i cant just run perforated pipes down the slopes. 

[JohnMo]

16 minutes ago, Post and beam said:

Which is why i question the need for any soakaway

If building regs says you need one - you need one. It does say that, so you do. Why waste effort trying to push against the tide?

[G and J]

And if emotionally you do need to understand the logic behind such rules (as I do) think about the potential erosion that uncontrolled rainwater flows could cause.   Houses with rainwear are very good at concentrating a benign rainstorm into a damaging localised flow. 

[JohnMo]

29 minutes ago, G and J said:

And if emotionally you do need to understand the logic behind such rules (as I do) think about the potential erosion that uncontrolled rainwater flows could cause.   Houses with rainwear are very good at concentrating a benign rainstorm into a damaging localised flow. 

Attenuation is required - or you end up with a big gapping hole (sink hole), is what you are saying. So building regs state soak away for a good reason. Or spend your life savings building a house, and have it fall in a big hole in 10 to 15 year time. Wouldn't like to have that conversation with the wife.

[Temp]

What soil type do you have? Have you done a percolation test? That might show a smaller soakaway is needed.

 

 

[Post and beam]

39 minutes ago, JohnMo said:

If building regs says you need one - you need one.

 I get it, i just dont understand the logic.

39 minutes ago, JohnMo said:

Why waste effort trying to push against the tide?

Becuase its a very expensive thing.

 

 As regards attenuating against a large sink hole.

The water from a soakaway will leach away at some rate.

 

The same volume of water from 4 x gutter pipes laid underground and sloping away would leach away at the same rate over a large area. But crucially be easier(cheaper) for me to install.

[Post and beam]

3 minutes ago, Temp said:

What soil type do you have? Have you done a percolation test? That might show a smaller soakaway is needed.

 

 

Soil samples were taken prior to groundworks from 3 sites on the plot. Based on whatever was discovered a percolation test was not required.

[G and J]

18 minutes ago, Post and beam said:

Soil samples were taken prior to groundworks from 3 sites on the plot. Based on whatever was discovered a percolation test was not required.

I thought they were different tests.  
 

Every day is a school day it seems.  
 

But, for the want of a few minutes with a bucket and spade you might discover something useful and save yourself some money.  I’m not talking sandcastles…

[torre]

I thought rubble filled was still allowed, but has to be about 3x larger than crates.

[JohnMo]

9 hours ago, Post and beam said:

Soil samples were taken prior to groundworks from 3 sites on the plot. Based on whatever was discovered a percolation test was not required.

Sorry that is nonsense. Where are you getting this bad information?

 

3.28 Percolation tests should be carried out to determine the capacity of the soil (see Approved Document H2 paragraphs 1.34 to

1.38). Where the test is carried out in accordance with Approved Document H2, the soil infiltration

rate (f) is related to the value Vp....

[JohnMo]

4 minutes ago, torre said:

I thought rubble filled was still allowed, but has to be about 3x larger than crates.

Even shows the drawing in building regs. Took me two minutes to find it.

[Big Jimbo]

1 minute ago, torre said:

I thought rubble filled was still allowed, but has to be about 3x larger than crates.

I'm surprised it's only 3 times bigger. When you think about the void in crates, against rubble. Want you soakaway to last a few years. Then rubble is the way to go. If you have got great draining ground, you might get away with rubble.

[Bonner]

9 hours ago, Post and beam said:

The same volume of water from 4 x gutter pipes laid underground and sloping away would leach away at the same rate over a large area

You need the capacity (volume) to contain a storm surge of rainwater. If you can demonstrate your pipes have 21m3 capacity, BC should accept it.

[Temp]

Perhaps I'm wrong but I calculated the crates needed at about £2500 after the VAT is reclaimed. Just over 100 crates at about £25 each.

 

https://skyplastics.co.uk/polystorm-soakaway-crate-x-120-22-46-20-tonne-1000mm-x-500mm-x-400mm-c-w-clips-shear-connectors-7.html?gad_source=1&gad_campaignid=11823408165&gbraid=0AAAAACepU-YY6R55dqvulcit98fUTrQ93&gclid=Cj0KCQjw2tHABhCiARIsANZzDWrXL3utZmoyuieDmmroFsJzj3egyX4nV9rKUkpDV7aYHLwJHst_RDUaAsp2EALw_wcB

Edited 23 hours ago by Temp