Not all SuDS are created equal: Impact of different approaches on combined sewer overflows

Prabhat Joshi; Joao Paulo Leitão; Max Maurer; Peter Marcus Bach

doi:10.1016/j.watres.2020.116780

Not all SuDS are created equal: Impact of different approaches on combined sewer overflows

Water Res. 2021 Mar 1:191:116780. doi: 10.1016/j.watres.2020.116780. Epub 2020 Dec 23.

Authors

Prabhat Joshi¹, Joao Paulo Leitão², Max Maurer³, Peter Marcus Bach³

Affiliations

¹ Institute of Environmental Engineering (IfU), Swiss Federal Institute of Technology (ETH) Zürich, 8093 Zurich, Switzerland. Electronic address: prabhat.joshi@outlook.com.
² Department of Urban Water Management, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland.
³ Institute of Environmental Engineering (IfU), Swiss Federal Institute of Technology (ETH) Zürich, 8093 Zurich, Switzerland; Department of Urban Water Management, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland.

PMID: 33422977
DOI: 10.1016/j.watres.2020.116780

Abstract

Sustainable urban drainage systems (SuDS) help in stormwater management by reducing runoff volume, increasing runoff concentration time and thereby improving the drainage system capacity. This study investigated the potential and cost-effectiveness of SuDS in reducing combined sewer overflows (CSOs). We simulated the performance of four SuDS techniques (bioretention cell, permeable pavement, rain barrel and green roof) at incremental levels of spatial coverage for a small urban catchment with a combined sewer system. We also used an Analytic Hierarchy Process (AHP) considering end-point CSO, land use, imperviousness, slope and elevation criteria to identify priority areas for SuDS deployment. Results showed that CSO volume attenuation ranged a maximum of 50-99% for the catchment, depending on the deployment strategy and underlying mechanisms of each technology. We also found that deployment of SuDS in AHP-selected sub-catchments improved CSO reduction only for rain barrels and green roofs, but not for bioretention cells and permeable pavements. SuDS were also a cost-effective retrofit option: for a 40% volume reduction, the SuDS cost, at most, 25% of the equivalent cost required for a large CSO tank. Outcomes of this study demonstrate the efficacy of SuDS in controlling CSOs, adding yet another tangible benefit to their increasingly recognised multi-functionality.

Keywords: Analytic hierarchy process (AHP); Combined sewer system, life cycle costing (LCC); Storm water management model (SWMM); Urban drainage modelling.

MeSH terms

Rain*
Water Movements*