How Should Residuals Be Managed in New Mains?

This month's question addresses the regulation of disinfectants in new water mains saying it is the responsibility of the water district wherein the activity occurred to monitor the practice of disinfecting new mains. The district should control all aspects of bringing the new main on line. If pipe disinfection is contracted out, the exact process must be specified in the contract documents and the district should retain strict control over the activity. Many contractors may not understand that a closed valve does not protect the main from cross contamination. The article calls out three methods of chlorinating new water mains from C651‐99: AWWA Standard for Disinfecting Water Mains.