Sources: American Concrete Pipe Association, Irving, Texas; CP staff
The John D. Parker East Texas Fish Hatchery, scheduled for early-2011 stocking, is among the latest instances of major high-density polyethylene pipe failure. Sections of 60-in. and 48-in. diameter corrugated HDPE drainage structure collapsed under 10 to 17 ft. of earth fill, and an 11,000-ft. stretch of the flexible pipe was determined to have questionable structural integrity. The system is designed to drain 42 large-mouth bass, channel catfish and bluegill ponds at the Texas Parks and Wildlife facility near Jasper. Replacement of the HDPE with 60-, 48- and 30-in. diameter reinforced concrete pipe (RCP) added $3.3 million to the agency's original $27 million budget, with design engineer HDR/FishPro covering the remainder.
"HDPE pipe was specified for an application that was much more suited to reinforced concrete. It was an accident waiting to happen," says Dr. Patricia Galloway, CEO of Pegasus Global Holdings, and an authority on drainage pipe systems. "Because corrugated HDPE pipe is a flexible material, not an independent structure like RCP, up to 90 percent of its successful installation is driven by the soil envelope surrounding it. It's imperative ÷ engineers account for a wide range of pipe-soil variables when dealing with HDPEÛfrom material properties to installation conditions to external loads, any of which can lead to catastrophic failure."