Effects of Disinfection on Newly Constructed Polyethylene Water Mains
|Publication Date:||1 October 2001|
At the first task group meeting, the following scope was adopted: To investigate and quantify, if possible, any effects on the durability of PE piping caused by disinfection per AWWA C651. Exposure times and concentration levels were chosen to be consistent with the requirements of the standard. Note that the disinfection practices outside the constraints used in this study (i.e., exposure time, etc.) may yield different results - e.g., if a contractor leaves a pipe full of concentrated disinfectant for 6 months.
Disinfecting of water mains has been a common industry practice for many years. The first AWWA standard covering this practice was approved in September 1947 (as 7D.2-1948). In 1986, the designation of the standard was changed to AWWAC651; the latest revision is ANSI/ AWWA-C651-92. The standard describes methods of disinfecting newly constructed potable water mains; mains that have been removed from service for planned repairs or for maintenance that exposes them to contamination; mains that have undergone emergency repairs due to physical failure; and mains that, under normal operation, continue to show the presence of coliform organisms.
Because the chlorine disinfection process puts pipe in contact with a strong oxidizer, a task group was formed in June 1993, within the PPI Technical Committee to investigate possible effects of disinfection on the durability of PE piping in potable water service. While C651 covers all piping materials used in potable water service, this investigation was confined to polyethylene systems. Chlorine was the only disinfecting agent investigated; chloramines were not evaluated. All tests conducted were short term, run at ambient temperature conditions on pipe samples made from particular polyethylene pipe compounds. The report is not to be construed as an indicator of the long-term performance of polyethylene pipe in general, or in the specific user's environment and operating conditions.