Depth Perception Tracking Sewer Performance Based on Design Guidelines & Regulatory Expectations

Since 2004, the Environmental Protection Agency (EPA) has issued 10 Consent Decrees to sewer utilities located in seven states within Region 4. Provisions within 50% of these agreements reveal an emerging regulatory expectation for sewer system performance, where the EPA has incorporated flow depths as leading indicators to highlight sewers that are more susceptible to sanitary sewer overflows (SSOs). When coupled with sewer design guidance from the American Society of Civil Engineers (ASCE) and the Water Environment Federation (WEF), these emerging regulatory expectations provide an effective framework in which to track, characterize, and manage system performance. Although these provisions have been limited thus far to EPA Region 4, they have broader implications for future enforcement initiatives in other EPA Regions and should be of general interest to sewer utilities across the United States. This paper provides an overview of these performance benchmarks as well as examples to illustrate their application.