The Plastics Pipe Institute Inc. (PPI) has published new guidelines in Technical Report TR-46 for the placement of flexible high-density polyethylene (HDPE) pipe using mini-horizontal directional drilling (mini-HDD) techniques.
TR-46 provides detailed information regarding site and bore-path planning, pipe design, drilling procedures, inspection and testing of mini-HDD installed HDPE pipe. Mini-HDD is a fast, economical and popular method that enables the rapid underground installation of corrosion-resistant HDPE pipe for water, gas and utility cables for runs of less than 600 feet, at depths of up to 15 feet and bore holes of up to 12 inches in diameter with minimal disruption to the surrounding site. The new mini-HDD guidelines for HDPE pipe can be downloaded as TR-46 from the PPI website.
Mini-horizontal directional drilling, also known as “guided boring,” is typically used for relatively shorter distances, shallower depths and smaller diameter pipe associated with local distribution lines as compared to maxi-horizontal directional drilling (maxi-HDD) typically used for long distances, greater depths and for larger diameter HDPE pipe. The PPI TR-46 document supplements the maxi-HDD guidelines found in ASTM Standard F 1962.