A recent study of all municipal sewer systems in Tennessee conducted by George Kurz (I/I Survey) shows that inflow and infiltration (I/I) represents approximately 104,720 million gallons per year. This accounts for 45% of the annual flow to treatment plants. Processing this extra water is estimated to cost at least $188 million annually statewide. This figure is conservative compared to the EPA’s recommendation in 2014 for using an O&M rate of $2 to $5 per thousand gallons− resulting in a cost estimate between $208 million to 522 million.
The Clean Water Act (CWA) establishes the basic structure for regulating discharges into U.S. waterways and setting wastewater standards for the industry. In 2012, the City of Memphis, Tennessee was cited for violations against the CWA. The EPA entered in a consent decree with Memphis requiring them to pay a total of $1,290,000 in civil penalties to resolve the CWA violations (EPA). The cost of consent decree penalties can surpass the cost of establishing a comprehensive inspection program. In some cases, the EPA can waive these fines municipalities demonstrates they have a strategy in place to address I/I. In either case, not addressing I/I can have catastrophic environmental and financial considerations.
In the white paper "Working Smarter Against I/I" we discuss the total system approach to combating I/I and the tools available to evaluate the different elements of your sewer system. With concepts presented in this paper, not only will you get a comprehensive understanding of the condition of your sewer system, you’ll also be ready to develop a plan to cut I/I by up to half.