From the article at http://www.muni.org/Departments/OCPD/Planning/Publications/Utility%20Corridor%20Plan/UCPChap3.pdf, full text here: WebPage:

“Powerlines can induce currents in metallic objects adjacent to the line. This effect is particularly prominent in corridors with long parallels. In addition to causing communication interference, audible crackling noise, and shock hazards, electric transmission lines can contribute to the corrosion of buried pipelines and cable sheaths under certain conditions. Finally, ’fault currents’ can float to the ground from the power lines (e.g., through lightning strikes) and move along the pipeline or buried cable, resulting in equipment damage and possible pipeline rupture which can lead to ignition and shock hazard…”