Robust Stormwater Management in the Pittsburgh Region: A Pilot Study

Key Findings

Analysis of Future Vulnerability

• Simulations of the recent past suggest that sewer overflow volumes are up to 15 percent higher than previously estimated
• Future rainfall, population, and land-use changes could further increase overflow volumes

Strategies to Reduce Future Overflow

• Expanding wastewater treatment plant capacity or cleaning existing deep interceptors could represent low-regret, near-term options
• Large-scale investments in source reduction, or combining source reduction with treatment expansion and/or interceptor cleaning, could help reduce sewer overflow, but with a wide range of uncertainty regarding cost-effectiveness and relative strategy performance
• None of these combined strategies, even including substantial source reduction investments, fully eliminates sewer overflows in current or plausible future conditions

GSI Cost-Effectiveness

• GSI strategies, evaluated in isolation, yield poor cost-effectiveness for overflow reduction under commonly used rainfall, capital cost, and GSI performance assumptions
• GSI and other source reduction strategies are more cost-effective in higher rainfall scenarios, and could provide hedging value against future climate change