The present disclosure provides an apparatus comprising a frame supporting a motor and a gearbox, and a bit assembly, the bit assembly comprising a shaft, having a first end and a second end, wherein the first end is attached to the gearbox via a gearbox output flange, a main bit assembly further comprising an upper cutting blade and a lower cutting blade attached to the shaft, wherein the lower cutting blade is located closer to the second end of the shaft than the upper cutting blade, an adjustable depth cutting guide attached to a bottom portion of the upper cutting blade, and a lateral cutting blade attached at the far end of the upper cutting blade and a guide bit assembly wherein the apparatus is attachable to a self-propelled vehicle.