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is important to recognize that the provision of local sewers alone is an inadequate response to deficiencies in sanitation and drainage. At the local level, it is necessary to ensure that connections are made to the sewers, but insufficient attention to the provision of trunk and collector sewers and treatment facilities will result in problems being transferred rather than eliminated. Thus, for example, while the provision of local sewers in Orangi has transformed conditions at the plot and lane levels, it has created pollution in the nalas running through the settlement and the creeks, such as the Lyari River, to which these discharge. Local sewerage cannot therefore be treated in isolation if severe environmental problems are to be avoided. Lahore provides an example of what this means in practice. In a city of over 4 million people, there is at present no sewage treatment and most of the city's sewage finds its way to the River Ravi, resulting in severe oxygen depletion downstream. While it is undoubtedly true that the hazards produced by this situation are significantly less than those which would ensue if no action had been taken to improve sanitation and remove sewage from residential areas, it is far from ideal. |
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The cost of secondary sewers in North-east Lahore, excluding the main trunk sewers and treatment facilities was about Rs1700 per household, bringing the total cost for secondary and tertiary sewers plus house connections to at least Rs3000 per household. The cost of trunk sewers and sewage treatment will add to this figure, making the overall cost of sewerage greater than that of on-plot sanitation, which in Pakistan is about Rs3000 per household. However, most on-plot sanitation systems do not cater for sullage water and the cost of providing sullage drains must be taken into account when evaluating on-site sanitation options. The point to take from this is that sewerage options should not be appraised on the cost of local sewers alone. |
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Regardless of the above, the lack of off-site sewerage is often an absolute constraint on the introduction of conventional sewerage at the local level. Problems arose in North-east Lahore because there was no trunk sewer available to take flows from the collector sewers constructed in the course of the project. Although such a sewer was under construction, its completion was delayed when the contractor encountered technical problems. In the meantime, a temporary pumping station was constructed under the North-east Lahore project but this only relieved the |
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