My folks live on an acerage that was built 84 years ago. They have a private well and septic system. They've been considering building a new garage/shop, and are concerned that the septic tank may be in the way, so they want to locate it.
They hired someone to locate it, but after 2 hours, the crew was unable to determine its location (I have no idea how they attempted to do this).
This acerage has only been owned by 2 other families, both of whom are known to my folks. They called them both up, and neither knows for sure where the tank may be, and neither has ever had the tank pumped (in 84 years of use).
There is a leeching field of sorts on the property, because years ago when some of the land was being farmed, it appears a plow cut part of the network, and there is a small (20'x10') part of a field that is perpetually wet.
Any ideas on how they might go about locating the tank?