From Land Based Methods
Conventional Pipe and Cable locators are an important tool used in most utility designation studies. The locators can be used in either a passive or active mode. The most common use for the passive mode is to find cables and conduits carrying live power (50-60 Hz) and communication cables (29-33Hz) signals. In the active mode, a current is transmitted or broadcast into a metal pipe or conduit and the path of the pipe/conduit is identified by following the signal with a portable receiver. It is used to trace out cast iron pipes, metal water and sewer lines, utilities that have trace wires, and inactive power and communication lines.
The maximum depth of investigation of a pipe and cable locator range from 15 to 18 feet depth and can be used in both conductive and resistive soils. Depth estimates can be accurate to within several inches in ideal conditions. For pipes or conduits that are to depths of 30 to 40 ft and that are accessible, a sonde transmitter can be pushed (or pulled) through a pipe and tracked with the receiver at ground surface. GeoView owns and is trained in the use of pipe and cable locators from Radiodetection, Subsite Electronics, Pipehorn, and the Schonstedt Instrument Company.