Drainage

[stanrog]

Between my house and back garden lawn I have a concrete patio (8ft width). This generally slopes to the lawn but also slopes a little bit left to right. Subsequently with moderate or heavy rainfall I get a large puddle where the patio meets the lawn near my right hand side boundary, my neighbours garage is the other side of the fence and thus drainage is restricted by the garage foundations. This puddle can take several hours to drain. Directly where the puddle is I have a brick path (10 bricks length x 8 bricks width) laid on earth, (not set in cement) leading to my garden shed (set on a concrete base).
I am thinking of digging a soakaway where the bricks meet the patio but am unsure as to what depth I should dig, the size of shale/stones to use, whether I should top the shale/stones with a layer of earth and what depth. Also whether it would be best to dig a small (spade width) square or a narrower trench type (ie say 10 bricks length by 1 brick width).
Any advice would be appreciated.

 

[TexMex]

Hello stanrog and welcome.

Your intended location is probably a touch close to the house. Ideally it should be more than 5m from the house. I'd be inclined to form a small trench (formed in concrete) down the side of the patio, leading to a rainwater gulley. This could then be piped into your soakaway.
This site may prove useful I find their calculations for size a bit tricky to follow. From my experience a good rule of thumb is sufficient volume to hold 20mm of water over the area that you are draining.

So assuming your patio is 2m x 2.5 a 20mm depth would give a volume of a tenth of a cubic metre.

 

[stanrog]

TexMex

Thanks for the welcome and advice. The site you referred me to was great and has changed my view of a soakaway being just a hole in the ground.

stanrog