Drainage problems heavy clay soil

Question

Hi I’d like to keep my garden dry all year round and would like advice on how to make the clay soil more porous to evaporate the water into the atmosphere. My back garden is lower than the front surface water drainage pipe so french drains aren’t an option. The back is joined with another neighbours back garden. The land slopes downhill from the back towards the neighbours. However I’m getting water coming in under the house at subfloor level which is about 1m deep and causing condensation and damp issues. My patio is about 80cm above the inside subfloor void. I’ll be removing the the patio soon and level to the sub floor level, and excavate 1-2m away from the house and put two or three soakways. However my problem is that most of the garden below 50-60cm is clay soil, I’m not sure how deep it goes and so the soakway might just become a mud pit as all around it will be clay too.

There is a build of vegetation at the end of the garden, which I’m assuming is preventing the water from escaping downhill. Is there any way of improving the structure of clay by adding sharp sand and 10-15mm stone and raked several times to improve the porosity and allow earth worms to burrow deeper into the clay.

As you can see in the picture, I dug a channel for the initial soakway, however it started to rain the next two days and the water just gathered there and has not moved since. It’s been 2 weeks and still the water hasn’t drained. I’m hoping I’m not on a high water table area, if so will lowering the back garden make matters worse? I don’t want the water to cause more damage inside the house and will welcome suggestions.

Answer 1

I think that this question would be best suited for a contractor. I’m not sure of the codes and laws in your area regarding digging and how you are allowed to drain water off of your property. You may have to get with your local authority and ask them what they would recommend when it comes to removing excess water from your property.