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12
Simplified Sewerage: Simplified Design |
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Simplified sewerage, often called shallow sewerage, is a low-cost sanitation technology pre-eminently suited to high-density low-income urban areas in developing countries (Sinnatamby, 1986; Sinnatamby et al., 1986; Bakalian et al., 1994). Its comdominial, or backyard, version is less expensive than its in-street version, especially when the sewers of the latter are laid under both sidewalks (Hamer, 1995), although it does require greater agency-customer interaction to ensure good operation and maintenance (Rondon, 1990; Watson, 1995). |
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In this chapter I wish to show how simplified sewerage theory leads to very simple design, once the basic design parameters are established. |
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The minimum tractive tension design approach (Machado Neto and Tsutiya, 1985) will be used as it results in shallower gradients (which may, of course, have greater operation and maintenance requirements), and a fully developed peri-urban area will be considered (i.e. an area in which there is no room for further housing development, so that any future increases in flow are due to increases in water consumption). The two resulting equations are: |
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where t = tractive tension, N/m2 (or Pa) |
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