As cities grapple with aging infrastructure and climate change, urban planners and utilities are facing difficult decisions about how to protect communities from flooding and pollution. A recent study in Camden, New Jersey highlights the complex interplay between combined sewer overflows (CSOs), sea level rise, and increased precipitation - offering valuable insights for municipalities across the country.
Combined sewer systems, which collect both stormwater runoff and sewage, are common in older cities across the United States. During heavy rain events, these systems can become overwhelmed, leading to CSOs that discharge untreated wastewater into local waterways, posing environmental and public health risks and putting municipalities at odds with Clean Water Act regulations.
The Camden County Municipal Utilities Authority (CCMUA) has been working to reduce CSOs through infrastructure upgrades and green stormwater solutions. To better understand the risks, researchers developed a high-resolution hydraulic and hydrologic model of Camden's Cramer Hill neighborhood. The model was used to simulate CSOs and flooding under various climate change scenarios, including increased precipitation, sea level rise, and compound effects.
The results paint a complex picture. While sea level rise alone could actually reduce the volume of CSOs by restricting discharge, it would significantly increase the duration and extent of flooding. Increased precipitation, on the other hand, would lead to more frequent and voluminous overflows. Compound scenarios showed intermediate effects, highlighting the need for adaptive management strategies.
One potential solution examined in the study was the disconnection of stormwater flows from an upstream municipality. This intervention showed promise in reducing CSOs under current conditions but became less effective as climate change impacts intensified.
The study underscores the importance of "climate stress testing" infrastructure investments. By modeling multiple climate scenarios, utilities can better understand the long-term performance of proposed upgrades and identify potential vulnerabilities.
As cities across the country grapple with similar issues, studies like this one provide valuable insights into the complex interplay between infrastructure, climate change, and regulatory compliance. By taking a proactive, data-driven approach to stormwater management, municipalities can work towards creating more resilient and sustainable urban environments.
