Building house on former agricultural land

Atomichamster

I'm currently looking at purchasing a building plot that is former agricultural land.  The land has lots of clay field drains and I'm wondering how this will affect the building once they are disturbed by the digging of foundations.  Do we reconnect them around the perimeter of the house? 

I'm not building the house myself so I'm totally clueless 😅. Thanks in advance!

diveunderthebonnet

If you mean they are land drainage clay pipes they can be replaced with plastic now ,most land drainage contractors use coils of plastic pipe that has holes along the top that catches the rainwater that seeps through the ground.

TELLIT01

If you are planning to purchase agricultural land does it have planning permission? 

 If so what restrictions are on it e.g. must the dwelling be occupied by somebody working in agriculture?

If no planning permission, have you spoken to the council planners?  

I realise these questions don't relate to the question but are important to your future building plans.

Apologies if I'm teaching my granny to suck eggs.

Section62

Atomichamster said:

I'm currently looking at purchasing a building plot that is former agricultural land.  The land has lots of clay field drains and I'm wondering how this will affect the building once they are disturbed by the digging of foundations.  Do we reconnect them around the perimeter of the house? 

Depends whether the flow is towards the house or away, and how far along the run the house will be.

There shouldn't be land drainage under a building, and an enthusiastic BCO might require you to get the land drains removed or filled before construction continues.  If the property is near the start of the drainage runs then they can probably be blocked just outside the footprint of the house.  If the drainage runs extend some distance from the house then they will need collecting and diverting elsewhere.

Section62

diveunderthebonnet said:

If you mean they are land drainage clay pipes they can be replaced with plastic now ,most land drainage contractors use coils of plastic pipe that has holes along the top that catches the rainwater that seeps through the ground.

Perforated plastic pipes should be installed with the holes downwards.

Atomichamster

TELLIT01 said:

If you are planning to purchase agricultural land does it have planning permission? 

 If so what restrictions are on it e.g. must the dwelling be occupied by somebody working in agriculture?

If no planning permission, have you spoken to the council planners?  

I realise these questions don't relate to the question but are important to your future building plans.

Apologies if I'm teaching my granny to suck eggs.

It's former agricultural land with planning permission.  

Eldi_Dos

Some land drainage schemes where implemented by Acts of Parliament, best to check if that applies in this case.

diveunderthebonnet

Section62 said:

diveunderthebonnet said:

If you mean they are land drainage clay pipes they can be replaced with plastic now ,most land drainage contractors use coils of plastic pipe that has holes along the top that catches the rainwater that seeps through the ground.

Perforated plastic pipes should be installed with the holes downwards.

Will the collected rainwater not run out the holes rather than run down the pipe ?

Section62

diveunderthebonnet said:

Section62 said:

diveunderthebonnet said:

If you mean they are land drainage clay pipes they can be replaced with plastic now ,most land drainage contractors use coils of plastic pipe that has holes along the top that catches the rainwater that seeps through the ground.

Perforated plastic pipes should be installed with the holes downwards.

Will the collected rainwater not run out the holes rather than run down the pipe ?

If the ground is saturated and the ground water level (aka 'water table') is above the invert of the pipe then water will flow into the pipe.  If the downstream pipe remains within a zone where the invert is below saturation level then the water won't run out of the holes because there will be water on the outside of the pipe preventing this... or also trying to get into the pipe.

If the downstream pipe enters a zone which isn't saturated (i.e. the groundis drier and the pipe is now above the 'water table') then some of the water in the pipe will flow out of the holes into the ground.... but that doesn't matter because the object of land drainage is to reduce saturation (aka 'lower the water table') where it is too high, rather than making sure all the water ends up in a ditch/stream/sewer/pond.  If some water 'leaks' out of the pipe into an area of drier soil then it will just increase the saturation of that soil until equilibrium is reached and the water stays in the pipe.  In effect the drain would be operating like a soakaway (environmentally, and in agricultural situations, adding water to drier areas of soil is better than pouring it into a watercourse)

If the pipe was being laid with the objective of collecting water (for example to store for irrigation purposes) then you might want to put the holes at the top, but then the drain wouldn't work until the 'water table' reached the top of the pipe (so a pipe's diameter higher), and you'd need to take care to make sure debris won't block the holes in the pipe.

gzoom

Rather than ask for advice on the internet from people who I suspect have never built a brand new house from scratch, go and engage a local architect/builder. 

Just make sure you are realistic about budget and timings.......Good luck, we didn't do brand new rebuilt but about 75% of the floor space in our current house did require total demolition when we refurbished. I enjoyed the whole process but that's not something universally shared with in the family.....Welcome the mad world of self builds

stuart45

I can't speak for others on this thread, but I've built a number of houses from scratch, a few of them having land drains running through them. They aren't normally a big problem provided you know about them before you start. On one job they were used to form a wildlife pond at the back with the overflow taken around the house to the front. 
I worked for a firm years ago that bought a building plot at auction in Crawley.
They didn't know it had land drains running through fed from an underground stream. When the trenches were dig out they continuously filled up. We had to get the digger back to dig another trench at the back and sort the drainage out by taking it round the house to a pond at the front.
At least you know about the issue before you start. It's worth talking to a land drainage specialist about rough costs for sorting the land before you make any offers. Another issue with this type of job is whether engineered foundations will be required, rather than standard strip foundations.