Garden drainage

[purpledaisy]

I'm buying a house with a large, sloping back garden. The survey has highlighted that there are problems with drainage, evident from dampness on the patio area at the bottom of the garden. When I looked around the property much of the garden was waterlogged, but I didn't think too much of it as there'd been a lot of rain in recent days.

However, can anyone give me an idea of what sort of work would be needed to provide adequate drainage for a waterlogged garden? It slopes up from the house, and is very steep for the last 15 metres or so. I want to use some of it for growing veg, which I know will be very hard if it's too wet.

Any advice very welcome!

 

[WabbitPoo]

Your patio is at the top of a slope and still has standing water? My, that's heavy soil. Or did I read it wrong?

Draining involved diverting ground water via drainage channels into a surface water drain or a soakaway. How steep is the slope? Any slope will obviously pull the water down it - if that is towards your house then you will need drainage gullies nearby to stop it piling up against the house. Do you have these already?

 

[Bodgeit and scarper ltd]

 

[purpledaisy]

Hi,

The patio is at the bottom of the slope - the garden slopes up away from it. It starts off fairly flat for about 10 metres, then slopes gently for about 15 metres, and is very steep for the last 15 metres or so. From memory the most waterlogged part was the gently sloping middle section - although as the surveyor has remarked on the patio being very wet, the drainage problem must carry on right down to the house.

I don't think there are any drainage gullies or anything at the moment. But I'm really hoping I can sort it out or the dreams of a veg plot in the garden will have to give way to the paddy field option for growing food...lol!

Is it quite straight forward to make a soakaway?

 

[WabbitPoo]

In principle, yes, but it involves digging a deep hole, which some would find hard. You need to be sure you aren't going to simply drain everyone else's garden too. When you say the patio is wet, do you mean the surface seems damp and green all the time? Is it in the shade?

 

[purpledaisy]

The patio gets a fair amount of sun, I think, but on the two occasions I've seen it it was wet underfoot (on dry, fairly sunny days) and I think a bit mossy too.

When you say a deep hole, how deep are we talking? I've had plenty of practice digging over allotments, but never tackled anything like this so have no idea what's involved. Also, where should the soakaway be sited?

Are there any 'how to' guides for garden drainage/soakaways online?

 

[masona]

Are there any 'how to' guides for garden drainage/soakaways online?

http://www.pavingexpert.com/drain03.htm

 

[r896neo]

You'd want to put in land drains in my opinion, these are to catch the groundwater not surface water.

Where, how many and how deep will depend on the garden and severity of the problem but the basic idea is dig a trench across your garden around 2 feet deep, put a few inches of pea gravel in the bottom then the land drain (like a tumble dryer vent pipe, but hard and with many small holes) then fill the rest with gravel and the top 4 inches with soil. As water drains down the garden it takes the path of least resistance into the gravel then into the land drain and away.

Of course it needs somewhere to go so you'd also need a drain to collect this water to go to a gulley? Or plant lots of conifers they are nearly as good at drying a wet area up!