A Simulation Tool for Assessing Sensor Performance in a Water Utility Contaminant Warning System

A set of software tools has been developed to enable performance testing of candidate on-line sensors in a utility-specific contaminant warning system design using simulation methods. Specific sensor performance characteristics such as noise, drift, detection level, and sampling rate can be input into the simulator and contamination scenarios can be run with a contaminant transport model such as EPANET using utility-specific pipe layouts. The sensor simulator is coupled with event detection software and together the two modules can provide an indication of how well the sensor will perform in a specific utility setting with user-defined contamination events. Water quality baseline data from utility measurements using on-line sensors are also incorporated into the analysis for a more realistic simulation. The software enables a determination of the rate of true positive, false positive, true negative, and false negative events during the simulation. Results from this analysis reveal that on-line residual chlorine and total organic carbon sensors combined with several different event detection algorithms can provide reliable detection for a variety of chemical contamination events. Study results further indicate this simulation tool concept is useful for pre-installation evaluation of contaminant warning system design in a specific utility setting.