Hi Bunnings Workshop Community!
This is a great knowledge resource.
I'm starting to embark on a project on my back yard to replace a failed retaining wall and add drainage to the ground in front of the wall.
The house is about 35ish years old and is cut into a sloping block, front(low) to back(high). So we have a flat area immediately behind the house about 20-25m x 4m then the retaining wall(20-25m long).
There was no drainage behind the redgum retaining wall (hence the failure), which I expect to be a similar age as the house. I will be replacing it with concrete sleepers and drainage!
My question though is regarding drainage of the flat ground area. There is an old French drain 65mm slotted coil about 1 metre in front of the retaining wall that spans the entire 20+ metre length, and is connected directly to stormwater pipe - not via a pit. It does not do a very good job of draining the water after heavy or sustained rain. The drain coil does not appear to have any sock, it has scoria rock around it and has some sort of loose shade cloth around it also.
I was thinking about adding another drain parallel about 2 m away and connect the 2 drains at regular intervals, but in addition to that I'm now thinking that maybe I need to dig out the old drain and renew it?
If digging it out and renewing it is the way to go then perhaps doing it properly with a 100mm slotted, socked drain coil and 300mm wide trench would be adequate on its own and not need any additional parallel drains?
Is 1 pit where the storm water is connected enough for a 20m drain?
Thanks
Simon
