Sustainability Assessment of Asset Management Decisions for Wastewater Infrastructure Systems—Development of a System Dynamic Model

Abstract

This paper presents the development of a novel system dynamics (SD) model for better understanding the interrelation and feedback mechanism between the wastewater collection (WWC) and wastewater treatment plant (WWTP) systems. Causal loop diagrams (CLDs) are developed and discussed to depict and understand feedback and inter-connections between physical, financial, and consumer sectors. The developed SD model is then extended to include the greenhouse gas (GHG) emissions, as a proxy for the environmental sector and for an environmental sustainability assessment of strategic decisions related to asset management planning of wastewater infrastructure system. It also adds new policy levers, such as population growth and urban densification in the social sector, and minimum fee-hike rates in the finance sector to enhance the representation of real-world conditions in the asset management planning. This new SD model will enable decision-makers to assess the sustainability impacts of their strategic decisions on wastewater systems, find synergistic cost-saving opportunities, and improve the sustainability performance of their asset management plans.

Sustainability Assessment of Asset Management Decisions for Wastewater Infrastructure Systems—Implementation of a System Dynamics Model

“…This study demonstrates the application and utility of system dynamics (SD) model developed by Mohammadifardi et al [2] to evaluate the future sustainability performance of policies and asset management strategies for wastewater infrastructure systems. Implementation of the developed SD model for an integrated wastewater collection (WWC) and wastewater treatment (WWT) infrastructure system of a medium-size municipality in Southern Ontario is presented for case-study demonstration.…”

“…Recently, Mohammadifardi et al [2] advanced the Ganjidoost [9] model by including the: (1) population growth, (2) urban development, (3) WWT plants' physical and financial models and (4) energy footprint and greenhouse gas (GHG) emission modules. They also presented several causal loop diagrams (CLDs) to show the cause and effect chain mechanism between the social, financial, and environmental sectors related to the wastewater-collection and -treatment asset management decisions.…”

“…Mohammadifardi et al [2] discussed that the WWC and WWT systems are directly linked to each other. Wastewater from urban areas is collected in WWC pipe networks and sent to treatment facilities.…”

“…The CLDs, which presents the cause-and-effect interactions between the various components in the physical, social, finance, and natural-environment sectors, as well as, the quantitative modeling and parameterization of the CLDs, are discussed in Mohammadifardi et al [2]. In the following section, initial data entries and assumptions needed for simulation of the asset management strategies are described.…”

“…The development of socially acceptable, environmentally friendly, and financially viable asset management plans compels understanding of the behavior of social, environmental, and economic systems. The complexity of planning decisions is compounded when different economic, social, and environmental dimensions of the challenge are inherently interrelated [2]. Moreover, it is realized that a strategic asset management plan should include assessment of impacts to/from other affected systems upstream and downstream [3].…”