AWWA WSC61374

The safety and security of major infrastructure systems in the United States, including drinking water distribution systems, has recently come under reassessment. Several chemical and biological agents have been identified that could constitute a credible threat against a water distribution system. In order to protect drinking water supplies, the U.S. Environmental Protection Agency (USEPA) initiated a program in 2003 to investigate real time sensors that may be used to trigger a contamination event and support early warning systems (EWS) within a water distribution system. These sensors monitor for standard drinking water parameters such as pH, free chlorine, oxygen reduction potential, dissolved oxygen, specific conductance, turbidity, total organic carbon, chloride, ammonia, and nitrate. The research was conducted on a recirculating pipe loop at the USEPA's Test and Evaluation Facility in Cincinnati, Ohio. The experimental results indicate that the parameters of free and total chlorine, total organic carbon (TOC), Oxygen Reduction Potential (ORP), specific conductance and chloride were consistently able to indicate a change in water quality due to injections of various contaminants into the pipe loop. Research is also being conducted to determine the minimum contaminant dose required to trigger a sensor alarm. Contaminants tested to date include secondary effluent from a waste water treatment plant, potassium ferricyanide, arsenic trioxide, nicotine, aldicarb, E. coli K-12 strain with growth media, insecticide containing malathion, and a herbicide containing glyphosate. Future testing with chemical and biological warfare agents has been initiated. Includes 5 references, tables, figures.