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Pipebursting AC Pipe Problematic, Says EPA
There was a time when the word "asbestos" was not primarily associated with serious health hazards.
Asbestos is a mineral fiber that has been widely used in a variety of building construction materials for insulation and as a fire retardant. Strength of its fibers and heat resistant properties ideally suited asbestos as a component for roofing shingles, ceiling and floor tiles, paper products, auto brake linings, asbestos cement and many other products, including utility pipes. Components of asbestos cement (AC) pipe are Portland cement, water, silica or silica containing materials and asbestos fibers.
AC pipe was widely used for potable water, sanitary sewer and storm drain pipelines from the 1940s through the 1960s.
"The asbestos fibers in lieu of reinforcing steel provided adequate strength with lower weight," said Kent Von Aspern, senior project manager, HDR Inc., an architectural, engineering and consulting firm that helps clients manage complex projects. Von Aspern has been involved in the trenchless technology industry for more than 20 years and has advised the U.S. Environmental Protection Agency (EPA) regarding the use of pipe bursting and pipe reaming as they relate to AC pipe.
Von Aspern said that in addition to light unit weight, AC pipe was marketed as having very good resistance to the effects of hydrogen sulfide corrosion and soils that were aggressive to steel pipes, and having low operating costs because the smooth walls of the pipe provided low friction factors.
But as health issues relating to asbestos were documented, federal regulations significantly restricted inclusion of asbestos in most products and the manufacture of AC pipe in the U.S. ended more than 30 years ago.
Still in abundance
However, much AC pipe remains in the ground today in active water and sewer systems. Von Aspern cites a 2004 study by the American Water Works Association (AWWA) which estimated 15 to 18 percent of the water distribution and transmission systems in the U.S. are comprised of AC pipe.
And much of that AC pipe, he said, needs to be replaced.
In a presentation at the 2008 UCT conference, Von Aspern said that 630,000 miles of AC pipe in water and sanitary sewer and storm drainage systems are near the end of their useful lives.