Do old septic tanks mess with metal detectors?

[nc-joe]

One side of the old church I've been searching has been nearly impossible to search. My MD freaks out. I jumps all over from iron to silver dollar. I can turn down the sens all the way and still jumps like a frog!

The area effected is around 20 x 30 Feet

 

[Sandman]

Metal rebars will do this. So will electric fields in the area or transformers. However I know a lake beach swim area that this happened to bug my Whites Beach Hunter ID II, but not my Excal. Go figure.........

 

[Mainedigger]

Joe...if the tank is near the surface it will send your detector haywire...as will any large iron object like that.

 

[sherpa t]

20 x 30 is pretty large for a septic tank, but I wonder if a water cistern might be under there. Eather way I have found any concrete pipe , storm water drainage etc. to be a big problem. The re bar in the concrete and the hollow ring of the form will stop my machines at all but absolute lowest sensitivity, the machines ring out as a good fairly shallow target on the edges and center of the underground pipe.

 

[stefen]

Could be a subadjacent gravel-filled leach field with cast iron drain lines set in the usual linear pattern.

That would account for the rectangular area.