What is a cat and sonde drainage investigation?

This Catalyst video shows how a CAT and sonde pipe investigation can be carried out to locate and trace buried pipes, especially non-metallic ones like made from plastic or clay.

A CAT (cable avoidance tool) is paired with a sonde (a small, battery-powered radio transmitter) attached to a flexible rod or robotic CCTV camera system. This allows the pipe’s location and depth to be plotted from above ground.