Hello. I installed a land drain (perforated pipe in pea gravel trench) 3 years ago which runs down one side of the garden towards the house and into a surface water drain. To be honest it didn't seem to work very well as the lawn was always waterlogged.
I am now building a walled patio area which required cutting the ground and land drain and re-routing behind the wall. While the trench was exposed, I noticed that there is no water coming through the perforated pipe but plenty coming through the pea gravel beneath the pipe.
I have attached a sketch.
First of all, is this unusual? And secondly, what is the best way to ensure all this water is captured and transferred to the surface water drain by the house?
Any help would be greatly appreciated.