Question
I am a landscape designer and redoing a back yard with beds and plants ect. There is a sunken area though all along the fence line, what can I do about it to build it up?

Answer
It has been a long time since my 'Design classes' but I remember that we were taught to find out the cause(s) of design problems before addressing the remedy since the remedy might cause us to redesign some, or even all of the elements.
So, is it the back fence, side fence or all the fences? It sounds like the sunken area is somehow associated with the fence construction. This is puzzling to me because fence construction usually results in excess earth excavated to accommodate the fence posts.
Sorry to have been of so little assistance. We can revisit if you find out more.