GPR is the newest technology for locating hard-to-detect utilities such as plastic piping that is used for water and gas lines. GPR is also the most effective way of detecting voids and underground storage tanks (USTs).
GPR works by sending a radio signal or series of signals into the ground. The returning signals provide information about changing ground characteristics with depth.
GPR is not without its limitations. GPR radio wave signals are absorbed by soils with high clay, moisture, or saline content greatly limiting exploration depth. GPR effectiveness is thus site-specific and varies greatly from place to place.