An effective method of pipeline mitigation is the gradient control wire system, which protects against inductive and conductive interference while providing cathodic protection.
Conductive interference due to currents flowing in the soil is of particular concern at locations where the pipeline is close to transmission line structures that may inject large currents into the soil during power line fault conditions.
Unless the pipeline is perpendicular to the power line, it will be simultaneously subjected to inductive and conductive interference. In most studies, the change in pipeline steel potential due to induction is essentially opposite in sign to the soil potential change due to conduction.
The magnitude of the conductive interference is primarily a function of several factors:
Excessive touch voltages due to conductive interference can be reduced by lowering earth surface potential vicinity of the pipeline or raising the pipeline potential near
* The ability to model soils with two or more layers, for accurate conductive interference calculations in non-homogenous soils (which are frequently encountered in practice).