Pipe Reaming Pipe reaming is a pipe replacement technique that uses a horizontal directional drilling (HDD) machine with minor modification. After pushing the drill rods through the old pipeline and connecting the rods to a special reamer (see figure below), the new PE pipe string is attached to the reamer via a swivel and towing head. As the drill rig rotates and simultaneously pulls back, the old pipe is ground up and replaced by the new PE pipe. Removal of the old pipe is accomplished by mixing the ground up material with the drilling fluid and transferring it to an exit point for removal via a vacuum truck. Directional drilling contractors or utility contractors who use an HDD rig can add inexpensively modified reamers of various types for different pipe materials and ground conditions. Pipe reaming is limited to non-metallic pipeline replacement. According to Nowak Pipe Reaming, Inc., the patent holder for the InneReam System, the surrounding environmental conditions (groundwater, sand, rock, concrete encasement, etc) that prohibit other procedures are not obstacles to successful installations (Hayward 2002).