Investigating Tradeoffs of Green to Grey Stormwater Infrastructure Using a Planning-Level Decision Support Tool

Elizabeth M Gallo,Terri S Hogue,Chelsea L Panos,Colin D Bell,Steven M Smith

doi:10.3390/w12072005

Elizabeth M Gallo, Terri S Hogue + Show 3 more

Open Access

https://doi.org/10.3390/w12072005

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Journal: Water	Publication Date: Jul 15, 2020
Citations: 15	License type: CC BY 4.0

Affiliation: Colorado School of Mines

Abstract

Integrated decision support tools are needed to investigate the tradeoffs of stormwater control measures (SCMs) and determine the optimal suite of SCMs based on the needs of watersheds. In this study, an urbanized watershed undergoing infill development (the Berkeley neighborhood located in Denver, CO, USA) was modeled using a modified version of the U.S. Environmental Protection Agency’s (EPA) System for Urban Stormwater Treatment and Analysis IntegratioN (SUSTAIN). The primary goal was to compare the relative performance between green and grey SCMs, use optimizations and a planning-level approach to assist in decision-making, and discuss how stakeholder and community preferences can shift which SCMs are optimal for the watershed. Green and grey SCMs have variable hydrologic performance based on design and function, and both offer benefits that may be important to decision makers. Our results showed that infiltration trenches and underground infiltration were optimal for reducing flow volumes while vegetated swales and underground detention were optimal for pollutant concentration reduction. Stakeholders value both of these benefits and so the optimal stormwater solution in the Berkeley neighborhood included a mix of green and grey SCMs. Determining the optimal SCMs while considering tradeoffs in costs and associated benefits was complex and multifaceted. Modeling results such as those presented here are critical for informing stakeholders’ decision-making process.

Highlights

Alterations to the hydrologic regime and degradation to water quality are major issues associated with rising percent imperviousness in cities undergoing urbanization [1,2,3,4,5]
We develop a modeling framework that encompasses green and grey stormwater control measures (SCMs) to (1) compare the relative hydrologic performance of green to grey SCM designs on a watershed-scale, (2) demonstrate how to use optimizations to perform a planning-level analysis, and (3) investigate how the varying priorities of stakeholders can shift which SCM solutions are considered optimal based on their needs
To improve the tool and better address the needs of stormwater managers, several changes were made to the SUSTAIN code in order to represent a larger suite of SCMs and allow a larger list of stakeholder criteria, resulting in an updated version of SUSTAIN called integrated decision support tool (i-DST) SUSTAIN

Summary

Introduction

Alterations to the hydrologic regime and degradation to water quality are major issues associated with rising percent imperviousness in cities undergoing urbanization [1,2,3,4,5]. States and the world have adopted stormwater management plans that utilize stormwater control measures (SCMs) ( known as best management practices, low impact development, and/or green/grey infrastructure). SCMs mitigate the impacts of urbanization [6,7,8,9,10] detrimental to both public health and the environment [11,12]. Water 2020, 12, 2005 from the Clean Water Act [13]. SCMs come in a wide range of designs that exist on a grey-to-green continuum where a particular There can be incentives to implement SCMs for the multiple hydrologic and ancillary benefits they offer [14,15,16], such as groundwater recharge potential [17,18] or improved eco-hydrologic conditions [19].

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