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determine the peak flow from equation (12.13); and |
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calculate the minimum sewer gradient from equation (12.10) with q 1.1 1/s (see Sinnatamby, 1986), and ensure that the actual sewer gradient is not less than this. |
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Table 12.2 is only valid for the choice of parameter values made. For ease of reference, these are: |
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d/D = 0.6 |
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k1 = 1.8 |
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k2 = 0.85 |
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w = 100 1cd |
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P = 5 |
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tmin = 1 Pa |
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n = 0.013 |
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r = 1000 kg/m3 |
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g = 9.81 m/s3 |
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For any other value(s), an equation similar to equation (12.14) has to be derived, and Table 12.2 recalculated for any desired range of sewer size. |
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Bakalian, A., Wright, A., Otis, R. and de Azevedo Netto, J. (1994). Simplified Sewerage: Design Guidelines. Water and Sanitation Report No. 7. Washington, DC: The World Bank. |
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Hamer, J. (1995). Low Cost Urban Sanitation in Developing Countries. B.Eng Dissertation. Leeds: University of Leeds (Department of Civil Engineering). |
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Machado Neto, J.G.O. and Tsutiya, M.T. (1985). Tensão trativa: um critério econõmico para o dimensionamento das tubulçãcoes de esgoto. Revista DAE, 45, 7387. |
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Rondon, E.B.N. (1990). A Critical Evaluation of Shallow Sewerage Systems: a Case Study in Cuiabá, Brazil. MSc(Eng) Dissertation. Leeds: University of Leeds (Department of Civil Engineering). |
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Sinnatamby, G.S. (1986). The Design of Shallow Sewer Systems. Nairobi: United Nations Centre for Human Settlements. |
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Sinnatamby, G.S., McGarry, M.G. and Mara, D.D. (1986). Sewerage: shallow systems offer hope to slums. World Water, 9 (1), 3941. |
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Watson, G. (1995). Good Sewers Cheap? Agency-Customer Interactions in Low-Cost Urban Sanitation in Brazil. Water and Sanitation Currents. Washington, DC: The World Bank. |
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