Modeling capital cost of sewer system assets

Abstract

The aim of this paper is the establishment of cost functions for the various assets of sewer systems, namely gravity and raising pipes, drainage and storm water pipes, service connections and pumping stations. Costs are defined as a function of the main physical characteristics of the assets, such as, pipe material and nominal diameter (for pipes and service connections) and flow rate, pump head and pump power (for pumping stations). A five-step methodology was followed: 1) data collection, processing and analysis, 2) present cost value calculation, 3) asset characterization and key parameters identification, 4) cost functions and prediction band estimation, and 5) cost functions validation. Cost and infrastructure data for construction contracts of wastewater systems managed by different Portuguese water and wastewater utilities were analysed. Cost functions were estimated based on multiple linear regression analysis.