Value of Information Analysis for Improved Decisions on Infiltration and Inflow to Wastewater Systems

Abstract

Infiltration and inflow (I/I) of excess water into wastewater systems pose significant technical, economic, and environmental challenges. This Master’s thesis explores the application of value of information (VoI) analysis as a decision-support tool to improve I/I-water management in private and separate sewer systems in Gothenburg. By com bining cost-benefit analysis with probabilistic modeling and Bayesian updating, a VoI framework is developed to quantify the economic value of acquiring additional infor mation. This is achieved by comparing optimal decisions before and after considering potential new data, to determine whether methods such as smoke and dye testing are economically justified. Using data from the Department of Sustainable Waste and Wa ter at the City of Gothenburg (Kretslopp och vatten), the model assesses the viability of three decision alternatives: intervention, no intervention, or further investigation. The results show that interventions are recommended in 67% of analyzed subareas, while further investigation is justified in 20%. Sensitivity analysis highlights the influence of several parameters, such as costs for measures and film inspections, detection accu racy, and especially property owner compliance, which plays a decisive role in cost effectiveness. While the model is applied to Gothenburg, its structure is generalizable and adaptable to other municipalities facing similar challenges. The thesis demonstrates that VoI analysis can enhance municipal decision-making by supporting more targeted, risk-aware, and cost-effective I/I-water management, ultimately contributing to more resilient and sustainable wastewater infrastructure systems.