Water Supply Delivery Failures—A Scenario-Based Approach to Assess Economic Losses and Risk Reduction Options

Municipal water mains are built with a target service age of several decades. In such a long life, breaks can occur, even multiple times. Water mains can be maintained before or right at breaks. The former is referred to as the preventive strategy, whereas the latter is the corrective strategy. Depending on the costs of repair, replacement, and failure consequence, different strategies should typically be implemented in order to achieve the optimal watermain management in terms of life cycle costs. This study aims to investigate the optimal scenarios for the two strategies based on a two-time-scale (TTS) point process used to model the deterioration of water mains. The corrective strategy is to determine the optimal number n, where upon the n-th break, implementing a replacement for water main is justified, compared to a minimal repair. The preventive strategy is to determine the optimal replacement time in terms of pipe survival probability Ps. Monte Carlo simulations are used to investigate the optimal n and Ps considering a number of influential factors, including model parameters of the intensity function and ratios of maintenance, replacement, and consequence costs. Then, the full distributions of the life cycle costs are characterized with the mean of total life cycle costs being the target for optimization. Last, a case study is illustrated to demonstrate the application of both strategies in real water systems. An important finding is that with a typical pipe diameter of 400 mm and length of 200 m, the optimal n is typically less than five, and the optimal Ps is below 50%.

“…Equation (5) indicates that the optimal n mainly depends on the cost ratios of C c C m and C r C m . If C m = C r , then obviously the main should be replaced at each break.…”

Section: Corrective Strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Optimal Maintenance and Replacement Strategy for Deteriorating Water Mains

Lin

Chen

et al. 2022

“…Even in Sweden, a country historically rich in water resources, the effects of climate change are starting to take a toll [4][5][6]. Consequently, it is becoming "increasingly necessary to consider 'unconventional' water resources in future planning" [2,7].…”

Section: Introductionmentioning

confidence: 99%

How Organization Models Impact the Governing of Industrial Symbiosis in Public Wastewater Management. An Explorative Study in Sweden

Södergren

Palm

2021

The industrial symbiosis (IS) landscape is evolving rapidly. While previous studies have argued for the importance of municipalities participating in the governing of IS, research on the implications of different forms of municipal organization is still lacking. This paper aims to investigate how municipal administration and municipally-owned corporations, as two forms of organization, impact the governing of IS in the water and sewage sector. This is explored in relation to the Swedish municipality Simrishamn, which recently underwent changes in the form of organization. Results show that municipal administration contributes to a more inclusive process where many actors can influence and bring ideas and perspectives on how to develop an IS. The risk, however, is that other issues within the municipality are seen as more pressing and, therefore, get prioritized before IS. In corporate form, the development of IS becomes more business-like as the focus is kept on core business. Technology development is strengthened as skills and competencies are promoted through the expertise of the employees. Drawbacks include processes becoming less transparent and political goals, such as citizen welfare not receiving the same level of priority as within municipal administration. There is also a risk that fewer perspectives are included in the process of developing IS, which may inhibit innovation, even if the results also indicate that an increased business focus of the corporate form strengthens the innovation capacity.

“…In 2018, there were about 8500 pipe bursts on the 111,700 km long public pipe network [19]. However, apart from pipe bursts, water disruptions can also occur due to other events related to the distribution systems, e.g., pump failures, or events related to the raw water systems, e.g., insufficient water quality or quantity, or to the treatment systems, e.g., operational errors and component failures in treatment plants [20][21][22][23]. According to the Swedish Water Services Act [24], the responsibility of the municipalities (i.e., the public water providers) is primarily to provide drinking water for residential use.…”

Section: Introductionmentioning

confidence: 99%

The Value of Water—Estimating Water-Disruption Impacts on Businesses

Sjöstrand

Klingberg

Zadeh

et al. 2021

Self Cite

As water serves as a necessary and often irreplaceable input in a range of goods and services, a disruption in water supply can cause lost production and sales for businesses. Thus, large benefits may be generated by reducing the risk of water disruptions. To enable selection of economically viable risk mitigation measures, the investment costs should be weighed against the benefits of risk mitigation. Consequently, quantitative estimates of the consequences of disruptions need to be available. However, despite the importance of water to businesses, the literature on their financial losses due to short and long-term water disruptions is still scarce. The aim of this paper is to estimate time-dependent water supply resiliency factors for economic sectors, i.e., a metric focusing on the level of output that businesses can uphold during a disruption, to contribute to better decision support for water supply planning and risk management. An online survey was used to gather data from 1405 companies in Sweden on consequences of complete and unplanned water supply outages. Results show that Food and beverage Manufacturing and Accommodation and food services are the two most severely affected sectors over all analyzed disruption durations.