A device for creating a trench in a ground surface includes a frame, an axle and a platform. A wheel is mounted to the axle and a motor is mounted to the platform. The motor is configured to rotate a drive shaft. A primary blade is removably mountable to the drive shaft. The primary blade has a first radius measured from a geometric center of the primary hub to a free end of a largest of the at least three primary tines. A second blade is removably mountable to the primary hub. The secondary blade has a second radius measured from a geometric center of the secondary hub to a free end of a largest of the at least three secondary tines. The first radius is greater than the second radius. A blade guard is mounted to the platform and generally covers the primary and secondary blades in an assembled configuration.