PC-based Simplified Sewer Design
Simplified sewerage is an important sanitation option in peri-urban areas of developing countries, especially as it is often the only technically feasible solution in these high-density areas. It is a sanitation technology widely known in Latin America, but it is much less well known in Africa and Asia. It is the purpose of this Manual to disseminate this technology more widely in the developing world, so that it can be used in peri-urban sanitation programmes and project to improve the health of poor communities. However, simplified sewerage is not just for peri-urban areas – it can be successfully and appropriately used in middle-and upper-income areas as well.
Section 1.1 discusses the need for sanitation in periurban areas, and Section 1.2 introduces the concept of simplified sewerage, especially its development and dissemination in Brazil. Ideas for promoting simplified sewerage in countries with no previous experience of the technology are given in Section 1.3.
The theory of simplified sewerage is presented in the Section 2. Section 2.1 discusses the design value to be used for the wastewater flow, in particular the design values for the peak factor and the return factor. Section 2.2. sets out the properties of a circular section, and Section 2.3 gives the Gauckler-Manning equation for the velocity of flow. Section 2.4 presents the hydraulic design based on minimum tractive tension; as shown in Section 2.5, this leads to the calculation of the minimum sewer gradient, and the procedure for calculating the sewer diameter is given in Section 2.6 The maximum number of households of a given size and a given water consumption that can be served by a simplified sewer of given diameter is discussed in Section 2.7. Section 2.8 and Annex II detail simplified sewer design trials using the Gauckler-Manning, Colebrook White and Escritt equations (which are described in Annex I).
Section 3 details the planning, management and design aspects of simplified sewerage. Technical and management options are discussed in Section 3.1, and sewerage planning in Section 3.2. Design parameters are considered in Section 3.3, which also details the design of condominial sewers and that of public collector (or street) sewers.
Section 4 describes the use of the Windows-based computer program developed for simplified sewer design.
University of Leeds, Leeds, UK, ISBN 0-904280-01-2, 110 pp.