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need not be the same at all times everywhere in all situations. For example, there is no valid basis to apply the same conservative standards in business districts (where breakdowns and repairs could create heavy economic losses and great inconveniences) as in the outskirts of a city (where the impact of similar breakdowns is less severe). In addition to economic aspects, the probability of breakdowns should be a prime consideration in design of a sewerage system. While Gakenheimer and Brando (1983) suggest additional research on uncertainty as it relates to infrastructure standards, they argue that there is enough evidence to move away from the stringent standards that have been adopted from industrialized countries; they contend that 'when resource-limited countries are using conservative standards, risk is lowered in one locality at the cost of fully exposing another'. |
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With this approach, depending on the prevailing 'engineering culture' and codes, the project engineer still retains the option to apply all or some of the suggested modifications. This review of experience with simplified sewers in Brazil shows that: |
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simplified sewerage technology is being successfully applied, and it constitutes a viable lower-cost alternative to the conventional system; |
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design modifications that have been introduced in simplified sewerage are based on sound engineering principles and have not compromised the level of service; and |
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construction costs have proven to be 3050 per cent less costly than conventional sewerage allowing sewer service coverage to be extended. |
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Unfortunately, information on simplified sewerage has not been disseminated much beyond Brazil. It is hoped that in time engineers in other parts of the world will become more familiar with it as increasing operational experience is accumulated and reported. |
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The information provided in this paper has been collected, in part, during discussions with the engineering staff of the state |
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