Subsoil Drain
A Subsoil Drain is a slotted or perforated pipe laid below ground, and designed to remove excess water from the surrounding soil. Subsoil drains are often surrounded by a geotextile material to stop soil particles entering the pipe.
Subsoil drains are sometimes placed behind the back of kerb to intercept subsoil before it can seep into a road pavement.
Image: Main Roads Western Australia