OK my property is six years old. Last year I noticed one part of my lawn some gray water. It was making the soil very soft when I ran it over with my lawn tractor. Thought it was the D box but instead I had my septic tank drained. It was full problem went away for a while. But now it’s doing it again and I can’t find my D box. Attached are some pictures of my septic plans and the problem. How do I find the DBox?