As far as French Drains go, the trench is usually 4' deep by 4' wide and however long it needs to be depending on how much the sq. ft. roof area it is collecting.
I wouldn't locate a driveway over the French drain, as it's filled with drain rock and that type of rock never settles or compacts.
To keep costs down, you can install them as parallel runway lanes instead of a full width driveway.
I wouldn't locate a driveway over the French drain, as it's filled with drain rock and that type of rock never settles or compacts.
To keep costs down, you can install them as parallel runway lanes instead of a full width driveway.