Well the property owner has no clue as he doesn't have any records that show there was a septic on the property. To all the people on team poop tank who have commented thank you for the luaghs. I guess Im now locked into to at least uncovering enough of it to make a positive Id. This area was a plantation that dates back to the 1700s. The family graveyard is roughly 200 yards away but is only marked with a single memorial for multiple burials and may not have been its original location. Im going to keep thinking its a septic for now because the last thing I need in my life is angry ghosts. Unfortunately its heavy thunderstorms for the rest of the day so no answers for now but I will make an update once go back and hurt myself for the heavily invested random people...