Waterlogged - French Drainage Installed

michaelbohan2

I had a really bad waterlogged garden (new build) so last year I dug it up (soil seemed OK quality) and put loads of french drainage channels into it.  The garden naturally slopes to the rear where there is a retaining wall with gravel behind it and drainage holes through it (I also added a couple more).  

I then rotavated the soil and put a nice lawn down and watered it as instructed.  

However, this year, the lawn has turned to crap and the garden is still really boggy (albeit not as bad).  I don't know if I'm going insane or not but I'm sure I can here the water trickling through the French Drainage. 

Is there much more I can do to it to rectify?

The garden gets very little sunlight for about 9 months of the year.

Dave Humby

This winter has been particularly wet and cold. The golf club monitors rainfall and it's been near-record levels where I live and I guess most of the country so both of those factors will be contributing to what you are seeing despite your good work. I'm sure you will see a significant improvement in the coming weeks. It doesn't sound as though there is much more you can realistically do. The only question I would have is just to make sure that the drains have a clear outlet and are not blocked and therefore backing-up in the garden. The only consolation is that without the work you undertook you would no doubt have even worse conditions to contend with. The water table will be high of course and that could also be a contributory factor. 

Obelixx

Dave's right.  We had a very boggy garden when we started in our Belgian home.  A drainage pond was dug and the ground quietly leveled away with a  very slight slope for the new "lawn" and beds and then a drain dug in a deep trench behind the house and leading to a sump with a pump to drive extra water to the pond or via another pipe to teh stream in the paddock next door.

After heavy rains you could go outside and hear the grassed area squelching to itself while it slowly drained.  Best not to walk on lawns or beds when they're that wet as you will compact the ground and make it worse.   As long as your drainage holes are not blocked it's probably OK and just needs a bit of patience and some dry weather.

michaelbohan2

Thanks for the reply.  The outlet holes through the retaining wall are all clear.
Although I terminated my french drain pipes into the bed of stones which sit in front of the retaining wall, rather than bringing my pipes straight through the wall so possibly the water is struggling to get through this bed of stones and out of the retaining wall drain holes.

Dave Humby

The brick wall will have concrete footings or below surface brickwork. It's possible that this is preventing your drains from draining and backing up in the system. 

michaelbohan2

michaelbohan2

These are the outlet holes to the land behind my house.  They are not blocked but there isn't much evidence of water coming out of them, it all seems to be seeping thought the breeze blocks.

Dave Humby

If that is the case then it looks like the water is not making it's way to your outlets and therefore backing up due to the breeze block wall hence why the garden is still wet. Do you have a blinding barrier of gravel between the wall and the lawn / garden or does the earth go all the way to the wall? You could try drilling a series of 10/15mm holes in the pointing between the blocks (1 or 2 per block on the same course as your outlets) to see if that improves the drainage. 

michaelbohan2

Hi dave, yes there is gravel between the wall and garden. I'll try drilling some more holes to see if that helps. I'll try not to go over board and cause the wall the collapse! 

jamesharcourt

@michaelbohan2 - I'm curious to know - how did you get on with that?  I am thinking of installing a french drain here in the UK but the termination area is my problem a little.  I want to know how do deal with the fact that a french drain works when sloped down, but this means the exit point is low down in the ground but needs to come back up again in order to "get out" of the property ... ?