I'm looking to create a french drain in the current swale about 8' behind my house foundation. We are at the bottom of a hill on that side and I would like to help get rid of as much hydrostatic pressure as I can by having a 3' foot french drain dug where the swale is currently.
However, we will eventually have a patio over where part of the french drain will be.
Will this create an unstable situation for the new patio?
I'm guessing some stone from the french drain will have to be excavated out of the french drain to the correct depth and then maybe landscape fabric over the stone to catch the patio base fill, and then compact the base as normal.
The size of the future patio and proximity to 100 year old tree roots give a narrow space for the french drain, so I can't avoid the patio on top of that part of the french drain.
So will the edge of the patio that is over the french drain always be at risk of sinking/settling?
Any experience with this issue would be appreciated.