A method for underground pipeline monitoring in which a continuous alternating electrical current having a current frequency in a range of about 1 kHZ to about 8 kHz is imparted onto a pipeline, producing an alternating magnetic field at the current frequency along the pipeline. Distributed along the pipeline is a network of RFID tag sensors which absorb an amount of energy from the alternating magnetic field. The impedance of the sensors is modulated, producing a modulated sensor impedance which is detected at a location proximate the location at which the continuous alternating electrical current is imparted onto the pipeline.