The first part of this paper deals with the technical improvements which have been made in the United Kingdom to ensure that sewerage rehabilitation is both effective and efficient. Severn Trent Water Ltd, which was one of the first organisations to employ a strategic approach to sewerage rehabilitation, has responsibility for the management of some 52,000 kms of sewer, 2250 pumping stations and serves a population of 8.3 million people. Planning and the progress made on implementing new methods for structural and hydraulic analyses within Severn Trent Water Ltd are illustrated. These elements together with the provision of high quality sewer records comprise a Drainage Area Study from which the investment needs of existing sewer systems are derived and programmed.
The second part of the paper deals with the topic of macro-planning of sewerage rehabilitation in a large organisation. At this level it is necessary to balance financial and manpower resources to obtain an overall programme for investment which is steady and sustained. The programme also embodies clear aims and objectives which provide adequately for customer needs.
The manner in which this has been achieved by Severn Trent Water Ltd is described and illustrated. The paper includes details of the programme of Drainage Area Studies and how the resulting information is collated to produce an overall investment programme. The main objectives are to clear the backlog of problems of flooding, pollution and sewer dereliction by a prescribed date, and thereafter to provide an improved service to customers by being able to respond to new problems quickly. The resulting increased activity in construction work creates extreme disruption to some communities. The perception of customers has been researched and the measures' introduced recently by Severn Trent to provide appropriate care for these customers who are inconvenienced by the works are described.