Measuring Flow that isn't There: Atlanta's Strategy for Sewage Spill Detection

Since its inception, the flow monitor has been known as a device to measure flow present in a sewer. The City of Atlanta is now employing an innovative technology utilizing a network of 125 flow monitors and 30 rain gauges to identify sewage spills by determining in real-time when flow is absent from their sewer system. The system is identifying spills as or before they happen.The web-based IntelliScan® System developed by ADS Environmental Services operates by learning both the flow pattern at each monitoring site and the response of each monitor basin to rainfall. During dry days the system continuously compares measured flow to what is expected for that time based on the flow pattern learned from several preceding days. Measured flow that is significantly less than anticipated results in a realtime callout to the IntelliScan system, which then can send alarms to users.During wet weather, IntelliScan compares the current flow measured at each site to what the system has learned to expect from current and antecedent rainfall. From recent history, the system learns a rainfall-to-RDII (Rainfall Dependent Infiltration Inflow) relationship for each monitor basin and is able to predict what current flow should be. Any measured flow that is significantly less than the predicted flow results in an alarm from the IntelliScan system. The result is that Atlanta now has the ability to detect sewage spills both in dry and wet weather, which has not been possible before. This new technology brings an entirely new level of protection against sewage spills.In addition to flow loss alarms, the system provides real-time high-depth alarms and pipe capacity alarms that allow an operator to anticipate possible overflows during both dry and wet weather.