Comparing the Economic, Environmental, and Social Impacts of Potable Reuse with Other Supply Options

Authors:

  • Stephanie Ishii, Ben Stanford, Grace Johns, Michalis Hadjikakou, Stuart Khan, Hazel Rowley, Tommy Wiedmann

An online survey was disseminated through the WRRF to assist in developing the TBL tool and methodology.

Participating utilities were asked "Which water supply sources does your utility current use, and which might you consider in the future (short- or long-term)?".

The survey found that most utilities are able to provide water supply options (WSO) cost data.

Multiple impacts of two WSOs are shown in this sample output of the TBL tool.

Direct and Indirect Potable Reuse (DPR and IPR, respectively) are increasingly being considered as two of many possible water supply options for water utilities in various locations throughout the US. However, as with any new water supply, potable reuse needs to be considered vis-à-vis other technologies or solutions, including a ‘no action’ scenario to determine the true value and economic impact of that supply option. To improve public acceptance and stakeholder support, it is critical that such comparisons be completed in a transparent, publicly accessible manner to facilitate not only management-level decision making but also public engagement and education about the water supply options. This calls for a comprehensive and objective evaluation methodology for comparing alternative water supply options, which lends itself to a triple bottom line (TBL) framework.

The TBL framework provides an established accounting approach for concurrently quantifying economic, environmental, and social implications for any business decision or project. At a time when companies and other organizations are expected to operate on the basis that long-term profitability should go hand-in-hand with social justice and environmental protection, TBL offers the ideal framework to ensure sustainable decisions. For water and wastewater utilities and other water-related authorities, TBL represents a widely accepted, transparent, and defensible means to compare the total (economic, environmental and social) benefits and costs of any investment vis-à-vis other alternatives, including the option of taking no action.

Through a WRRF-funded study, we are developing a specialized TBL tool and associated methodology that goes beyond conventional practices to evaluate water supply options. This work draws upon the social sciences to provide quantitative measures of social indicators, as well as benefits from input-output lifecycle assessment to quantify environmental impacts. The framework also engages stakeholders throughout the process but provides accountability to minimize “gaming of the system” to achieve a desired outcome. Working within an established TBL framework, we are using hands-on participatory workshops and case studies to define, test, and validate a methodology for comprehensive evaluation of the various supply options that incorporates stakeholder perceptions and value systems.

In this presentation, we discuss the developed framework including the social, environmental, and economic indicators and our methodology for integrating a multi-criteria decision analysis component into the decision tool. We also demonstrate how this tool has been applied through at least one case study site.

For more information, please contact the author at sishii@hazenandsawyer.com.

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Horizons Fall 2017 (pdf)

Horizons showcases significant water, wastewater, reuse, and stormwater projects and innovations that help our clients to achieve their goals, and can help you achieve yours. Articles are written by top engineers and process group leaders, demonstrating and explaining the beneficial application of a variety of technologies and tools.

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