Effects of urban growth without attendant infrastructure: A Case study of Zimmerman, all unsewered high density residential estate in Nairobi

Abstract

The problem of sanitation is perceived within the context that human waste and waste water disposal is concerned with relocation of waste from the point of generation to a more suitable and non-detrimental site a factor which is not strictly observed in the Third World countries. The problem of sanitation is more acute in urban areas more so in the newly developing residential neighbourhoods. Urban population growth has led to conversion of previously low density areas into high density ones but sanitation methods suited for low population density areas continue to be used. The effects of this on urban population is worth a study considering that poor sanitation in the Third World countries has been responsible for the low life expectancy and serious health problems in these countries. The work of previous researchers and scholars has documented a list of attempts at improving problems in provision of infrastructure and services in urban areas. The background of poor urban infrastructure has been attributed to uncontrolled increase in urban population coupled with inability of local and central governments to continue with provision of infrastructure. The outcome of this has been undesirable urban environments. This has continued to be the case despite the existence of an articulate infrastructure and service development policies at global national and individual urban centers' scales. Sewerage system has been one of the most neglected infrastructure despite the profound polluting effect exhibited by untreated waste water. As such sanitation especially in the upcoming residential neighbourhoods has been deplorable. Lack of sewerage services and infrastructure has been attributed to expensive installation running and maintenance costs of sanitation facilities which have been developed in the Developed Countries. Other socioeconomic needs take up all the available resources leaving behind little or none to sanitation facilities. To counter this tendency the suggestion of lowering the design standards of the sanitation facilities from the West has all been frequently suggested. The argument has been that effectiveness of sanitation facility is not necessarily reflected in high installation running and maintenance costs. Further, both households and community participation has been found to be a viable ingredient in ensuring provision and maintenance of efficient infrastructure and service among them sewerage systems. Zimmermann's the study area's physical attributes together with high residential density relative to the surrounding describe an anomalous development. Historical development of the estate reflects a series of irregularities leading to conversion of a formerly grazing field to a high residential estate albeit without infrastructure. A population of about 56.000 people resides in an area of 400 acres. The estate is characterized by a relatively reliable and constant water supply and house units which have wet cores and water closets within them. These characteristics show high water consumption hence high waste water production rate. In the absence of a convectional sewer system, cess pits. septic tanks and conservancy tanks which are meant for low population density areas. Are used. Effectiveness of waste water tanks in Zimmermann was evaluated on the basis or the amount of generated waste water and the capacity of the environment to contain it. The capacity of the environment to contain the generated waste water was based on the capacity of waste water tanks and the frequency of exhausting vis-a-vis subsurface condition namely the areas with black cotton soils high water table and flat topography. The high amount of generated waste water was found to be three times the capacity of waste water tanks meaning that two thirds of raw waste water generated in the zimmermann is released into the environment without proper control. The costs associated with outflow of raw waste water from the tanks were evaluated. These costs include high monetary costs in form of exhausting charges to the land lords and environmental costs to the residents. The latter costs include unpleasant odours and muddy streets in the residential neighbourhood. Poor-sanitation-related diseases and actual and anticipated accidents as a result of presence of deep waste water tilled tanks which have poor or missing accessories in a residential neighbourhood were also rampant. The conclusion drawn from the research is that use of waste water tanks in Zimmermann estate is ineffective because these facilities facilitate relocation of waste water from the house units into the immediate area, thereby allowing direct contact of human waste and waste water with human beings. This has other indirect implications such as diseases and unpleasant residential environment on top of actual and anticipated physical injury risks to the residents. The ultimate solution to poor sanitation situation in Zimmermann is a convectional sewer system. To make this affordable lowering of its design standards and specifications has been suggested as part of long term solution. Residential units developers should take up the responsibility of providing attendant infrastructure to the neighbourhoods that they create While the ultimate solutions await to be taken , remedial measures which will improve sanitation situation by reducing the polluting effect of waste water have been suggested. To reduce the possibility of accidents, waste water tanks should be constructed on the side of the residential block and away from the gates and open spaces within the block. Further separation of waste water from the different quarters of the house units and subsequent separate disposal tanks were suggested, This is in addition to a recommendation that conservancy tanks would be more efficient than septic tanks and cess pits Still as part of solving the current problems emanating from use of waste water tanks. Ventilation of the tanks and construction of some which have a higher surface area-volume ratio are suggested as a way of reducing odours from the waste water tanks.