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Substituting equation (12.10) in equation (12.11), rearranging and changing the units of D from m to mm: |
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Equation (12.2) can be expressed using, as typical values, k1 = 1.8, k2 = 0.85, w = 100 1cd and r = 5, as follows: |
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where N = number of households served. |
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Substituting equation (12.13) into equation (12.12) gives: |
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Table 12.2 can be established using equations (12.12) and (12.14), and this can be used directly to design each stretch of sewer, as follows: |
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determine the number of households to be sewered; |
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select, from Table 12.2, the sewer diameter; |
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| Table 12.2Table 12.2 Maximum number of households served by simplified sewers of 100300 mm diametera | Sewer
diameter
(mm) | Maximum number
of households
served |
| | 100 | |
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234 |
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| | 100 | |
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234 |
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| | 150 | |
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565 |
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| | 225 | |
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1360 |
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| | 300 | |
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2536 |
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| | abased on equation (12.14) (see text for inherent values of parameters, such as household size, assumed). |
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