Hi guys, just want to start off by saying that this site is a gold mine. I have been using it for advice as a DIY'er and its proved great.
I have been landscaping my garden on a new house that we bought last year, the garden soil content is heavy clay with a slope towards the rear of the property.
In the photo bellow you can see that I have dug the front half level and retained the rear with sleepers stood upright burried in concrete.
I also had the excavator remove a further 7-9" of clay so I could back fill with top soil ready for the new grass.
I back filled with approx 8 tonnes of fresh top soil before installing new turf.
after 24 hours of the turf being down and rainfall during the evening it became very apparent that I had drainage problems as the turf was heavily water logged, although it would dispearse over a period it still left the soil very jelly like,
My closet point to tie drainage into the sufrace water drain was right below the kitchen window. My only problem is that its fairly shallow being only 300 mm from surface to bottom of 110mm drainage pipe.
I think that i will have to install further drainage accross both lawn sections using perforated pipe. I was wanting to use 60mm OD due to my being unable to go down the required depth.
I also wanted to run perforated pipe from the far lawn under the path that runs between the two lawn sections and into the 110mm pipe you see sticking out from under the path that i have tied into the surface water drain.
any advice on this problem would be great, I work offshore and try and do bits and bobs when I am home.
Thought I would post some previous photos showing the lead up to the pictures you see above, also shows how well my garden holds rain water after only a coule of weeks.
Same old story with new builds, take out the good stuff and sell it, replace it with clay and crap then don't give you a garden. You only need a gentle slope and the water will run. Read the land drainage page Here before you do any work. There is a link to a case study on that page too.
Thanks for that, I have given that page a read and its got some great stuff on it.
My problem appears to be getting the required depth as you can see from the above pictures the surface water drain is only at best 300mm below the surface.
I believe that a run of 1cm per 1m should be suffice?
What is the likelyhood of this derain working if i place it in a herringbone style accros both lawns and tie it into the surface water drain and it only being 200-300mm bellow the surface of the turf?
Any help/pointers is much appreciated as I'm about at my wits end with it.
1cm per 1m will give you a run of around 1:100 which would suffice for self cleansing of a 50mmØ pipe perforated pipe.
Personally I would run a 100mmØ half perforated (with perforations facing downwards) along the bottom of the garden runing perpendicular to the house (shown in red) with a T socket at your outlet(blue) with rodding eyes at either end (pink).
I would run 2 no 50mmØ perforated pipes down to this line with branches (orange) of clean stone. Surround each branch in Terram 1000osa (or similar) along with all pipe channels. Rather than turf over the 100mmØ line could you not dress off with a 50mm layer of decorative stone?
The fact that the outlet is only 200-300mm below the surface would not be an issue. All it would mean is that your storage capacity of the French drain is reduced. You could always excavate a further 500mm or so below the invert to create more storage for the event of heavier rain – but looking at your photographs it would seem that your clay holds water quite well and would take a good while to dissipate.
Thanks for that info it's much appreciated, I have purchased some 50mm ID perforated pipework and intend to lay it when I get home in 2 weeks to help with the drainage.
I will report back with my install and get approval
