Computer Aided Rehabilitation of Sewer and Storm Water Networks

Abstract

and storm water systems in cities worldwide suffer from insufficient capacity, construction failures and pipe deterioration. The consequences are structural damage and local floods leading to inflow of water into basements, traffic disturbances, street and surface erosion, and pollution of local receiving waters. The reasons for the problems are the combined effects of ageing infrastructure, urbanisation and climate change. European cities spend in the order of 5 billion € per year for wastewater network rehabilitation. This amount will increase significantly over the coming decades, due to network ageing. Today, the rationale behind rehabilitation decisions is unclear. Decisions are often made ad hoc and, in the best case, are based on practical experience after failures appear (reactive approach). This is the background for a project in the 5 Framework Programme in EU, Computer Aided Rehabilitation of Sewers and Storm water networks (CARE-S). The project objective is to establish a rational framework for sewer network rehabilitation decisionmaking. CARE-S aims to improve the structural and functional reliability of the wastewater networks (risk of inand exfiltration, collapse and blockage due to pipe deterioration, hydraulic overloading resulting in flooding and/or receiving water pollution). This is combined with the analysis and, where necessary, upgrading of the network capacity to take care of runoff from rainstorms and snow melt in urban areas. The ultimate product will be a Decision Support System (DSS) that will enable municipal engineers to establish and maintain effective management of their sewer networks. In other words: Rehabilitate the right sewer at the right time by using the right rehabilitation technique at a minimum total cost, before serious failures occur (pro-active approach). Some analytical tools to assess the technical or functional state of sewers or the needs for rehabilitation are available or are under development. Usually, though, they do not take into account all aspects of rehabilitation decisions, and they only have been applied for a limited number of wastewater services. The objectives of CARE-S are to improve these tools, link them and to make them usable for the formulation of a rehabilitation strategy. The DSS will include the following elements (Fig.1): a tool generating Performance Indicators (PI) that are relevant for rehabilitation decisions, including analytical and statistical procedures to assess and forecast some of the PIs a procedure to define the socio-economic and environmental risks of malfunctioning sewer systems a database to be used for choosing an appropriate rehabilitation technology a tool to define the best long-term strategy for rehabilitation investments several tools that allow to assess the hydraulic, environmental and structural conditions of the network including their change over time. a multi-criteria decision (MCD) tool supporting the choice of high priority rehab projects a software package, called Sewer Rehab that will enable consultants and wastewater service providers to use the above products according to their individual needs and available data base. Fig. The general architecture of the CARE-S Rehab Manager Some preliminary results are: 1. A PI (Performance Indicator) tool addressing information relevant for sewer and storm water network rehabilitation has been developed. It is based upon comprehensive and Hydraulic Reliability Tools Structural Condition Tools Deterioration Process Tools Socio-economic Analysis Tools Input