Shepherd, Headford, Jordan, Reeves, Walton
The World # 2006 Washington DC
In Europe polyethylene (PE) has been chosen almost exclusively for gas mains for many years because of economic, technical and safety reasons but in the water industry a number of different materials are still used for pressure water mains. Indeed at sizes above 355mm (14 inch) most new large diameter water mains are still laid in ductile iron. Often these large diameter water schemes are designed by consultant engineers who are not familiar with the benefits that can be achieved by using flexible and weldable PE pipes. Therefore material choice is often based on the cost of the pipe itself and the cost of the total installation, including the cost of trenching and the bedding/surround, is not considered. It is even more unlikely that the operational and maintenance costs are taken into account. Therefore, it was decided to develop a whole-life costing model for large diameter water mains in which the full life cost of Polyethylene (PE), Glass Reinforced Plastic (GRP) and Ductile Iron (DI) water pipes within the range 400 to 900mm (16 to 36 inch) can be compared (N.B. it is possible to adjust the model to cover other size ranges).