Design: permanent works

Abstract

The pipe and the access shafts are the only permanent parts of a pipeline construction and the parts the client is paying for. The cost of the pipes and shafts, particularly for a deep sewer construction, represents only a small percentage of the total cost of the installation. The larger percentage by far is the cost of the temporary works: the mobilisation of equipment, the excavation and restoration. This high cost of placing the pipe to the required position in the ground, together with the appalling consequences of failure, should be reason enough for designers to select materials of the highest quality which meet the technical requirements for their purpose. Engineers who are swayed by the initial cost of materials rather than their long term value do little but contribute to the growing volume of sewer rehabilitation of the future.