GPR sends a radar signal down to the anomaly under ground and then is bounced back to the antenna and displays on the computer screen. Ground Penetrating Radar in Kalispell
This machine works the same way as ground penetrating radar the only difference is it has the ability to look into concrete, It sees rebar, utilities, voids ect.
Private utility locator. 60% precent of the utilities in the United States are private, it is up to the land owner to have them located for both safety and the expense of damage.