Permitting of Combined Sewer Systems/Clean Water Act: U.S. Environmental Protection Agency Public Notices Draft Guidance

The United States Environmental Protection Agency (“EPA”) has public noticed draft guidance (“ Draft Guidance”) to:

. . . to clarify and inform future National Pollutant Discharge Elimination (“NPDES”) permitting actions for communities with combined sewer systems.

See EPA-HQ-OW-2023-0475.

EPA states that the objective of the draft Guidance is also to:

• Highlight available approaches for permitting combined sewer overflow (“CSO”) communities nearing completion of the projects and activities defined in their Long-Term Control Plan (“LTCP”)
• Summarize options under the Clean Water Act that are articulated in the 1994 CSO Control Policy and the option to use the 2012 Integrated Planning Framework to look holistically at future investments in controlling wastewater/stormwater discharges

CSOs discharge untreated sewage mixed with stormwater to waterways during heavy rain events. This occurs with some old collection systems that were designed to overflow when rainfall or snowmelt exceeds the capacity of the treatment facilities. In other words, the combined flow of wastewater and stormwater can overwhelm the system. These events are denominated CSOs and subject to the Clean Water Act NPDES permitting program.

Addressing CSOs can be a significant issue. Three of the strategies that can be employed include:

• Sewer separation (i.e., constructing a second system of pipes to keep stormwater separate from wastewater)
• Increase storage capacity (i.e., store combined wastewater during heavy rains and slowly release it to the wastewater treatment plant over a period of time)
• Treatment (i.e., move the combined wastewater/stormwater to a treatment plant before discharging to a waterway)

EPA’s Draft Guidance components include:

• Background
• Monitoring to Inform Next Steps
• Planning for Future CSO Permits
• Integrated Planning for Combined Sewer Systems
• Ensuring Equity and Climate Resiliency in CSO Communities
  • Consider Equity in Current and Future Infrastructure Planning and Projects
  • Plan for Climate Ready, Resilient Infrastructure Investments

A copy of the Draft Guidance can be downloaded here.