Optimization of Real‐Time Control With Green and Gray Infrastructure Design for a Cost‐Effective Mitigation of Combined Sewer Overflows

• Published in: Water resources research 2021-12, Vol.57 (12), p.n/a
• Main Authors: Jean, Marie‐Ève, Morin, Camille, Duchesne, Sophie, Pelletier, Geneviève, Pleau, Martin
• Format: Article
• Language: English
• Subjects: Case studies; Combined sewer overflows; Control; Cost analysis; cost minimization optimization; Design; Design parameters; Distribution; Green infrastructure; Hydrologic data; hydrological and hydraulic simulation; Infrastructure; Integration; Mitigation; Optimization; Parameter sensitivity; Parameters; Rain; Rainfall; Rainfall data; Robust control; Sewer systems; source control measure; Spatial distribution; Storage facilities; sustainable urban drainage systems; Uncertainty; Urban water solution design; Wastewater
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2021WR030282

An innovative optimization‐simulation framework is applied to a case study of the Province of Quebec, Canada, to optimize the spatial distribution of green infrastructure (GI), the capacity and location of gray infrastructure, and the parameters specific to real‐time control (RTC) operating rules of a sewer system for reducing combined sewer overflows (CSOs) frequency and volume. GI, gray infrastructure, and RTC are applied either individually or in integration through eight optimization scenarios which are simulated over a nine‐year period of historical rainfall data. Among all scenarios, spatial optimization of GI with RTC leads to maximal CSO volume reduction (98%) and is the most cost‐effective option analyzed (70$/m3 of seasonal average CSO reduction compared to 140$/m3 for the scenario involving gray infrastructure alone). However, it requires a high GI implementation level and the CSO frequency under this scenario is sensitive to varying GI design parameters. The findings suggest that the best alternative for CSO control is the integration of the optimization of green and gray infrastructures with RTC as it still provides high CSO volume reduction (95%) and remains a cost‐effective solution (90$/m3 of CSO reduction), while providing robustness under cost and design uncertainties. Plain Language Summary An innovative method is applied to a case study of the Province of Quebec, Canada, to optimize the spatial distribution of green infrastructure (GI), the volume and location of storage facilities, and the operational rules of a smart control strategy of a sewer network for reducing the number and volume of overflows of untreated wastewater (CSO) during rainfall events. GI, storage facilities, and smart control strategy are applied either individually or in different combinations through eight different scenarios. Spatial optimization of GI with smart control leads to maximal CSO volume reduction (98%) at the lowest cost (70$/m3 of seasonal average CSO reduction compared to 140$/m3 for the scenario involving storage facilities alone) as compared to other options, but requires a high GI implementation level and the GI design parameters can considerably impact its performance. The results suggest that the best alternative for CSO control, providing robustness under cost and design uncertainty, is the integration of the optimization of GI and storage facilities with smart control as it still provides high CSO volume reduction (95%) and remains a cost‐effe