Evaluation of Green Alternatives for Combined Sewer Overflow Mitigation

The mitigation of combined sewer overflows (CSOs) is a significant environmental and financial challenge, particularly for older urban communities where these overflows are most prevalent. Communities are increasingly examining more environmentally sustainable "green" alternatives for addressing these problems. These green solutions are often endorsed because of the additional environmental, social, and economic benefits they produce. A growing body of reports and case studies - briefly reviewed here - describes and attempts to quantify these benefits as economic impacts. Most estimates of economic impacts have focused on a comparison of the costs for construction and operation of green alternatives to traditional infrastructure approaches. Some of these have attempted to estimate the economic value of communitywide environmental and aesthetic gains, and other economic benefits are occasionally identified. This report develops a broad framework, or taxonomy, for identifying and organizing the socio- economic impacts of sewer infrastructure projects. It focuses on a green project in Cincinnati, Ohio that has adopted broader economic goals. The report then uses this example to illustrate how the taxonomy can be used by community officials engaged in storm water management to obtain a fuller understanding of the economic benefits of green alternatives for CSO mitigation.