Thank you for your reponse to my problem. We dug up part of the lines and exposed the entire d-box. The lines appear to be in good shape, in fact they don't appear to have been used at all. This is very upsetting, but at least the cost of repair has been low. We re-connected the septic to the d-box even though the box seemed to have dropped. We used slight elbow fittings to re attched and hope to have no more problems. I hope my experience will enlighted others to the possiblility that their contractor could be at fault for their failed systems. Thanks again for your input.