Field testing phase shows success in using low-cost sensors to automate detection of illicit discharges

SCCWRP and Orange County Public Works have built a small network of field sensors that can generate a continuous stream of real-time flow and water-quality data on dry-weather runoff as it moves through storm drains.

Field testing on the eight-site network, which was completed in October, found that the low-cost Internet of Things (IoT) sensors can be successfully used to automate detection of illicit pollutant discharges, which can pass rapidly through storm drain systems. Stormwater agencies are required under their discharge permits to actively monitor storm drain systems to detect and eliminate illicit discharges.

During the study, the sensors successfully identified four of the five intentional discharges that were created upstream of monitoring sites to mimic illicit discharge events. By contrast, Orange County stormwater managers over the past decade have only successfully identified a handful illicit discharges through traditional in-person, manual inspections.

In the coming months, SCCWRP will prepare a report summarizing lessons learned from the pilot study and develop a workplan for how Orange County can scale up its sensor network.