Use of Continuous Recording Water-Quality Monitoring Equipment for Conducting Water-Distribution System Tracer Tests: The Good, the Bad, and the Ugly

An emerging and innovative technology that is a possible alternative to manual sampling is the use of continuous recording water-quality monitoring equipment (CRWQME) for collecting multiple ion-specific tracer data. Advantages of using CR-WQME include the ability to record continuously water-quality events (including unplanned events) during a tracer test at small time intervals of 15 minutes or less. This recording provides realtime data when using hand-held logger equipment to query the CR-WQME at each sampling location. Also, the labor needed to conduct the test is reduced. Disadvantages could include the cost of multiple ion-specific sensors and units for large or complex systems, the effort required to calibrate the equipment by setting up a test-site water-quality laboratory, and the reliability of the equipment for long-term monitoring events. In this paper the authors assess the use of CR-WQME in conducting a tracer test at a military installation in North Carolina. Using results obtained from the tracer test, the authors found that CR-WQME is an emerging and innovative technology that still requires refinement and the use of some grab samples to provide quality-assurance and quality-control procedures during the tracer test. However, CR-WQME is an excellent option when designing and conducting multiple parameter tracer tests for water-distribution system model calibration activities.