Simplify the following text for a Grade 7 native English-speaking person.
Original: Gardanne is a commune in the Bouches-du-Rh Ã ne department in southern France .
Simplified: Gardanne is a commune of 20,700 people ( 2005 ) . It is found in the region Provence-Alpes-C Ã te d'Azur in the Bouches-du-Rh Ã ne department in the south of France .