Improvements in the collection and treatment of sewage are critical to reduce health and environmental hazards in rapidly urbanising informal settlements. Where sewerage infrastructure is not available, road-based faecal sludge management options are often the only alternative. However, the costs of faecal sludge transportation are often a barrier to its implementation and operation and thus it is desirable to optimise travel time from source to treatment to reduce costs. This paper presents a novel technique, employing spatial network analysis, to optimise the spatiotopological configuration of a road-based faecal sludge transportation network on the basis of travel time. Using crowd-sourced spatial data for the Kibera settlement and the surrounding city, Nairobi, a proof-of-concept network model was created simulating the transport of waste from the 158 public toilets within Kibera. The toilets are serviced by vacuum pump trucks which move faecal sludge to a transfer station, and from there a tanker transports waste to a treatment plant. The model was used to evaluate the efficiency of different network configurations, based on transportation time. The results show that the location of the transfer station is a critical factor in network optimisation, demonstrating the utility of network analysis as part of the sanitation planning process.

Many theoretical urban sanitation planning approaches exist, but there is limited evidence of the successful implementation of these approaches, prompting questions about their suitability, especially in complex urban environments in low-income countries. Using primary and secondary data from Lusaka, Zambia, we explore possible limitations of these theoretical planning approaches in informal peri-urban areas. The findings show that while the "enabling environment" aspects stressed by the literature are weak here, these limiting factors are significantly affected by a poor planning culture and inherent dynamics of power, politics and history. A fuller understanding of the local situation is needed to support the transition of planning approaches from theory to reality, so that real progress in sanitation service delivery can be achieved in complex urban environments.

Challenges for the future of urban sanitation planning: critical analysis of JohnKalbermatten's influence. AbstractDuring the 1980s, John Kalbermatten and his colleagues at the World Bank revolutionised urban sanitation planning. During the last 30 years urban sanitation planning theory has evolved from an engineering focus to a more participatory, multi-disciplinary and userfocused future, informed largely by the work of John Kalbermatten. This paper looks at a number of the most important urban sanitation planning approaches that have emerged postKalbermatten and seeks to trace the influence of Kalbermatten's work on their theoretical underpinnings and characteristics. The extent to which other ideas, such as the sanitation value chain, have increasingly been incorporated into planning approaches are discussed and some of the challenges affecting successful urban sanitation which lay outside of planning are considered. Final comments centre on common themes occurring in practice, the future exploration of which offers potential to inform successful sanitation delivery in the future.

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This paper presents a methodology to support the implementation of Faecal Sludge Management services in informal settlements in Lusaka, The Republic of Zambia.