Underground Iron Pipe

[rich54]

Hello. I've been trying to help a friend find an underground shutoff valve on a water line buried below the frost line (40 inches?). Using a Vanquish 540 and finally found the line using the pin point button. I can trace out the course of the pipes but a strange thing occurs. I find 3 parallel 'images' of the pipe - about a foot apart. Very consistent lines. Are there such a thing as 'electromagnetic shadows' or something? Strange. Question number 2 is can I somehow find the shutoff valve. It is supposedly brass and should be down 12 inches or so. I've tried non-ferrous settings and get no consistent detection along the pipe. I would have thought that a brass valve would make the detector go nuts!

Thanks
Rich

 

[Picketwire]

Deep or small iron responds to the edge of the coil better than the middle, and the toe and heel are the most sensitive. The 540's coil is about a foot long. As for question 2, disc mode is nowhere near as deep as no motion all metal. It may not be deep enough to detect the valve. I would think it would be below the frost line also. It might give an indication by a wider or stronger signal in pinpoint than the pipe or maybe a null in the sound.

 

[tvr]

Question number 2 is can I somehow find the shutoff valve. It is supposedly brass and should be down 12 inches or so.

If it is the main feed to a property, the valves are normally not far from a road or right of way near the property edge. If you can't find it, might try asking the water company to locate it.