Getting More From Flow Monitoring: How to Maximize the Value of Sewer Flow Monitoring Information

Recent years have brought increasing pressure from Federal and State Regulators for more comprehensive management of collection systems in an effort to significantly reduce releases of untreated sewage to the environment. This has created a need to understand what the flows in the collections systems are doing at all times and during each season. In turn, this has created an increase in reliance on flow monitoring to understand actual system performance and increase reliability in predicting future wet weather performance and bottlenecks. Numerous flow metering technologies are available; each with their own set of advantages and disadvantages. When due care is taken to implement flow monitoring studies, numerous benefits are realized including: 1) Determining all the flow components including average dry day flow, wastewater production, and Inflow & Infiltration (I/I); 2) quantifying areas of excessive I/I and verification of post rehabilitation I/I reduction; 3) Use of the flow data to generate powerful scattergraphs that "tell the complete story" about system capacity at each monitored location; 4) Improving operation and maintenance (O&M) through defensible wastewater billing, real-time surcharge detection and alarming; and 5) Reducing O&M and capital projects costs through the quantification of backwater caused by flow throttling.