Valuing information for sewer replacement decisions

Abstract

Decision-making for sewer asset management is partially based on intuition and often lacks explicit argumentation, hampering decision transparency and reproducibility. This is not to be preferred in light of public accountability and cost-effectiveness. It is unknown to what extent each decision criterion is appreciated by decision-makers. Further insight into this relative importance improves understanding of decision-making of sewer system managers. As such, a digital questionnaire (response ratio 43%), containing pairwise comparisons between 10 relevant information sources, was sent to all 407 municipalities in the Netherlands to analyse the relative importance and assess whether a shared frame of reasoning is present. Thurstone's law of comparative judgment was used for analysis, combined with several consistency tests. Results show that camera inspections were valued highest, while pipe age was considered least important. The respondents were pretty consistent per individual and also showed consistency as a group. This indicated a common framework of reasoning among the group. The feedback of the group showed, however, the respondents found it difficult to make general comparisons without having a context. This indicates decision-making in practice is more likely to be steered by other mechanisms than purely combining information sources.

Application of the Mathematical Simulation Methods for the Assessment of the Wastewater Treatment Plant Operation Work Reliability

“…Negotiations between the involved managers of the water and sewage facilities and other similar activities should be also considered [63]. It is observed very often, that some decisions about the sewage infrastructure facilities is partially making based on the intuition, without any reliable confirmation or arguments [64].…”

The Recycling Potential of Submersible Sewage Pumps in the EU

“…Sewage pumps play an important role in wastewater collection and treatment because they have been among the main electromechanical equipment of these facilities around Europe for over 30 years [1][2][3][4][6][7][8][9]12]. Their operational life is around 15-20 years and thus a significant number of them are non-functional any more [2,[7][8][9][10][13][14][15][16]. The need for replacement of these pumps has increased the number of pumps that must be disposed of in the forthcoming years [17].…”

“…According to manufacturers' datasheets, the effective or satisfactory operational life time of sewage pumps in wastewater management facilities is estimated to be 15 years. When their operation is no longer satisfactory, they are replaced [5,6,[8][9][10][11]14,22,23]. In this work, centrifugal submersible waste water pumps are primarily categorized by their power.…”

“…Another important consideration is that the life expectancy of sewage pumps (around 15 years, even if their maintenance, repair procedures and operation during these years follow the manufacturer directives, precautions and limitations) could be extended, with the ultimate result that a relatively small number of pumps will reach their end of life [3,[5][6][7][8][9][10][11][12][13][14][15][16][17]23]. Many of these facilities have been in operation for more than 15 years in Greece and around the EU, resulting in an increased number of sewage pumps becoming non-functional.…”

“…Usually the pump will be replaced when it fails, due to a broken component or an unacceptable drop in output. It should be noted that 100% separation of copper, iron and aluminium metal parts is not achieved during scrap treatment, leading to fractions of lower recycling quality due to remaining impurities [5,6,12,14,24,25].…”