Pipelines cover the earth like a web of arteries. They supply us with everything from oil and gas to ammonia, water and even beer. For decades they have been among the safest and most effective means of distributing a wide variety of substances that would otherwise require far more expensive truck or rail transport. But there’s a hitch: pipeline operators need to monitor these vast networks completely whether they are above ground or buried. Indeed, the thickness of the earth layer with which many critical pipelines are covered is a key safety concern. In Europe, for instance, underground gas and oil pipelines are legally required to be covered by at least one meter of soil. In the U.S., which accounts for about 65 percent of the world’s 2.17 million miles (3.5 million km) of pipeline, pipelines are typically buried three to six feet underground*.
Aerial monitoring is generally conducted by helicopters, which fly over pipelines every two to four weeks. However, such visual inspections are expensive and generally lack the equipment to determine whether the layer of earth covering a pipeline is sufficiently thick.