Rodney : What state do you live in? Type of soil? The garden that the wife had planted was a 100 feet from the drain field o f the sepic system. The system carried that far after 15 years. Had it checked and it was O.K., but it bleed that far, past the septic tank. The depression almost like a sink hole, if you start digging there, tie a rope around you first. Use a Bolin at both ends, no slip. I would hate to have you drop out of sight! Try driving a metal rod down at the center to see if you hit anything, but wear the rope. In other words, don't become Wiley E. Cayote! Regards Marc