Rehabilitation cost modelling of water supply infrastructures at the leading edge sustainable asset management

Abstract

Asset deterioration due to aging and stress causes increased operation and maintenance costs, water losses, quality of service reduction and a worse quality of supplied water. To maintain or improve the performance of existing water networks, both old and modern systems and technologies for inspection and control, operation and maintenance and appropriate rehabilitation should be used. The current paper presents the development of rehabilitation cost functions for different types of storage tanks (e.g., ground and elevated) based on known physical characteristics of the assets (e.g., volume and height) and their comparison with the construction costs. The followed methodology is a five-step procedure: 1) Database construction and analysis; 2) Present cost calculation; 3) Key parameters identification and cost function establishment; 4) Rehabilitation cost functions estimation; 5) Cost function testing and validation. Rehabilitation cost and infrastructure data from several Portuguese water utilities were used. Multiple linear regressions have been used for modelling rehabilitation costs and regression curves were divided in civil works and electromechanical equipment and electrical facility costs. Obtained cost functions have been tested and present high coefficient of determination and statistical significance. This research provides a comprehensive and robust methodology for rehabilitation cost function estimation and develops rehabilitation cost functions that are grounded on a set of terms with an associated physical meaning.