Magnetic ranging is used in the oil & gas industry, but shallow horizontal drilling is also used underneath obstacles such as rivers, to pass utilities and avoid underground structures. Magnetometers on drilling equipment can be used to join two boreholes, and provide information about the presence of pipes, cables, or any other ferromagnetic material. Depending on the nature of the tool, Grad-13 gradiometers,  Mag-13 sensors, or lower-cost  Mag690, Mag648/649 sensors may be used.