Jun 15, 2017

Robust Stormwater Management in the Pittsburgh Region: A Pilot Study

by
Jordan R. Fischbach, Kyle Siler-Evans, Devin Tierney, Michael T. Wilson, Lauren M. Cook, Linnea Warren May
,
RAND

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