Twinwall size

[S J H]

I need to put a pipe in around 200m long, to drain around 3000 sq m of yard and buildings, it has a good fall, just wondered on a size diameter?

Tia

 

[devonboy]

would have thought 9inch.

 

[S J H]

would have thought 9inch.

That's what I was thinking, I don't want to be tight. I used an online calculator and it worked out 4", there's a fair jump from 6" to 9"

 

[br jones]

9 is around 40 per 6 m ,12 is 75 per m ish

 

[br jones]

That's what I was thinking, I don't want to be tight. I used an online calculator and it worked out 4", there's a fair jump from 6" to 9"

We do have some mighty big storms ,drainage calculator for houses in wales say can it handle 360mm of rainfall in 6 hr,that is roughly the size of storm that fell on boscastle ,the council man told me ,

 

[S J H]

We do have some mighty big storms ,drainage calculator for houses in wales say can it handle 360mm of rainfall in 6 hr,that is roughly the size of storm that fell on boscastle ,the council man told me ,

Thank you I'll have a look at that,

 

[S J H]

We do have some mighty big storms ,drainage calculator for houses in wales say can it handle 360mm of rainfall in 6 hr,that is roughly the size of storm that fell on boscastle ,the council man told me ,

Sorry was that 9" ?

 

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[Half Pipe]

If you have a good fall pipe will create a decent suction increasing flow.
Is it essential that drain can cope with extreme heavy rain!? Can yard surface be shaped to to direct excessive water along surface keeping it away from shed doorways etc if it's raining that heavy does it matter if small stream starts on surface

 

[S J H]

If you have a good fall pipe will create a decent suction increasing flow.
Is it essential that drain can cope with extreme heavy rain!? Can yard surface be shaped to to direct excessive water along surface keeping it away from shed doorways etc if it's raining that heavy does it matter if small stream starts on surface

They'll be 2 yard drains that will be drained from gulleys and they'll be a direct feed from the buildings. I'd say about half from yard and half from the buildings.

 

[S J H]

@Kevtherev do you have any suggestions Kevin? @Hurdle bunter ?

 

[kill]

Go as big as you can sensibly afford. I done a similar stretch 3or4 years ago to get rainwater away from buildings and within 2years I'd dug it back up as an extra building added and drains needed increasing in size so future proof yourself or be prepared to pay twice

 

[Boohoo]

That's what I was thinking, I don't want to be tight. I used an online calculator and it worked out 4", there's a fair jump from 6" to 9"

9" will flow more than twice the water that 6" will and 12" will flow four times the water that 6" will. You don't want to go too big though because silt is more likely to gather in a big pipe carrying a small amount of water.

 

[S J H]

9" will flow more than twice the water that 6" will and 12" will flow four times the water that 6" will. You don't want to go too big though because silt is more likely to gather in a big pipe carrying a small amount of water.

Yes that's true, always thought 9" it's just twice the price. But as above, I want it to be future proofed.

 

[Kevtherev]

Without seeing it it’s a job to tell what you need but make sure you go plenty big enough to cope 9inch will take serious water but bigger cost over 6inch.
Choose quality twin wall like polypipe civils if you can.
Put plenty of access manholes in key areas for future maintenance.

 

[Paul E]

9" is enough.

 

[Bernardbean]

Paid tenner a meter for 12 inch on similar job last month....

 

[Sharpy]

Would be worth finding what the optimum fall for your chosen size would be, a big help in stopping silting up.

 

[S J H]

Without seeing it it’s a job to tell what you need but make sure you go plenty big enough to cope 9inch will take serious water but bigger cost over 6inch.
Choose quality twin wall like polypipe civils if you can.
Put plenty of access manholes in key areas for future maintenance.

Without seeing it it’s a job to tell what you need but make sure you go plenty big enough to cope 9inch will take serious water but bigger cost over 6inch.
Choose quality twin wall like polypipe civils if you can.
Put plenty of access manholes in key areas for future maintenance.

Thanks Kev, is naylor stuff ok?

 

[Kevtherev]

Thanks Kev, is naylor stuff ok?

Yes their twin wall is fine just make sure you protect the pipe with plenty of fine material before backfilling and any heavy traffic areas you could cover it with pipe bedding or scalpings.
If the drains aren’t very deep I have covered them in lean mix in high traffic areas like lorry or feeder wagon access.