Drainage channel help advice please

[Andyc192]

Hi I have sloped back garden that dips down into my garage. It floods when there is very heavy rainfall. I've bought some drainge channels to help said the water flow to the grids drains I already have now..

Ok so I understand I have to dig a small trench so that the channels can be cemented in place. I aim to have them running along side my house around the garden and infront of my garage. 11metres .

My question is do I have to dig up my old grids/drains so the channels sit over the top of them with a hole in the bottom so water to gush though. I have a drain/grid for the gutterring on the roof also have another grid for my kitchen waste water and also have a grid for rain water thanx

 

[Bonni]

Ground level should be 6 inch below DPC. When I fit drainage channels, I connect the end of the channel into a rodable gulley. If I've connected the channel via the bottom, I've done so by an S trap, only because I redid/installed the waste pipes.