Tim , found the problem , least i recall i had an option to change runway alt and the taxiway and ramp .
These screens are on a brand new Virgin HD with only the mesh , the other flatten bgl did not even make a bump .

as you can see were you have placed the fence line , it blends in perfect with the outside

as you can see in the distance

i recall at times i doubled up on flattens for the simple reason a Bump in the middle of a runway of all things , maybe the proximity of the river