Investment appraisal for sewerage schemes: benefit assessment

River pollution and a decaying sewer network are both major problems in the UK. The scale of the problems inevitably means that investment to improve river water quality and to reduce the risks of both collapse and flooding from sewers must necessarily be phased over a number of years. The number of individual projects involved adds to the difficulties of prioritising these investments. The scale of investment involved is also so large that the expenditure must be justified in comparison to other possible uses of that money such as hospitals, education or roads. A desktop methodology has therefore been developed which enables the evaluation of the benefits which result from reductions in the risk of flooding, or of sewer collapse, and also of the benefits of river water quality improvement resulting from improvements to point sources of discharge. -from Authors