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Tutorial under consideration may not be the most cost-effective tal issues — stakeholders are often more open to participatchoice at first glance, but may nonetheless warrant serious ing in the process. Stakeholders are able to recognize at the consideration because they provide benefits beyond the outset that the issues of priority to them will have a place in main objective of the options being evaluated. (Conversely, the analysis and related deliberations. TBL can help reveal where a project may have ancillary negative impacts that the utility and community should A Stormwater Management, consider in their deliberations.) In other words, when there Green Infrastructure Example are multiple options to address a specific water-related In Philadelphia, longstanding issues with stormwater and issue, and one or more of the options generates important combined sewer overflows (CSOs) needed to be addressed "co-benefits" to the community, then a TBL approach can through high-level investment in long-term compliance strathighlight the value added of such options and help guide a egies. The Philadelphia Water Department (PWD) and city better informed public discourse and decision making. administration envisioned that many important communityWide-Ranging Applicability. One example, discussed wide values could be enhanced if they could use green infrabelow, pertains to stormwater management, where triedstructure (GI) elements as key portions of their compliance and-true engineered solutions such as collection and storapproach. However, they needed to obtain buy-in from the age tunnels (gray infrastructure) are known to be highly U.S. EPA that an approach that entailed a mix of green and effective — albeit expensive — at helping manage storm gray infrastructure would be warranted, in lieu of a more flows. However, green infrastructure approaches — even traditional gray-only compliance approach. if potentially less certain in long-term performance and We assisted the PWD in conducting a quantitative TBL O&M; costs — tend to provide very high co-benefits that revealed the high number of social and environmental to the community in addition to their contribution to benefits that could be obtained by the GI-inclusive approach. stormwater management. Significant social and enviThe TBL approach helps ronmental benefits were estireveal where and how a mated for the GI-inclusive utility, and the community approach, when compared it serves, may be better to the alternative relying off (in overall net benefits) solely on gray infrastrucby using an approach that ture. Figure 1 provides our may not appear as costdepiction of the TBL results effective (when evaluated for Philadelphia, comparing on a narrow basis), or that the net advantages of the relies on less traditional and GI-inclusive approach relapotentially more expensive tive to a gray-only approach approaches. At a minimum, of similar total cost. Because it helps utilities and the the two alternatives have communities they serve the same cost, the finangain a more complete piccial corner of the TBL triture of the choices they Figure 1: Quantitative TBL depiction of large benefits for CSO and stormwater angle in Figure 1 is a wash. controls including a large green infrastructure component in Philadelphia, compared have and the implications to a traditional gray-only approach (present values over a 40-year time horizon). However, the social benefits of their potential choices are considerable, with GI (see Figure 1). investments providing significant reductions in urban heat In another type of application, TBL has helped characterisland-related heat stress mortality, improved property valize how and why the total value added by capturing and ues, improved air quality, energy savings, local employment generating energy from digesters and other processes often opportunities, and several other important beneficial outmakes great sense in terms of financial, environmental, and comes. Ultimately, PWD was able to gain EPA acceptance social outcomes. This biosolids-oriented application doveof the GI-inclusive approach as part of its CSO Long Term tails nicely with the wastewater sector's ongoing transition, Control Program. as reflected in the Water Environment Federation's rebranding of wastewater treatment plants as "water resource recovWater Reuse ery facilities." And Desalination Example Engaging Stakeholders. We also have found the TBL We have also used quantitative TBL assessments to demonapproach to be a highly effective way to include stakeholdstrate the high net value for utilities that have included water ers within an active dialogue. By explicitly recognizing at reuse and/or brackish groundwater desalination (desal) in the outset that the approach is intended to capture the their water supply portfolios. In these instances, the investbroad array of impacts — including social and environmenments in reuse and desal were known to be quite high when 20 wateronline.com ■ Water Online The Magazine