Impacts of a solid waste disposal site and a cemetery on groundwater quality in Harare, Zimbabwe
Among the more significant large municipal facilities to impact on the quality of shallow groundwater are landfills and cemeteries. At the same time, there is an increasing small-scale use of shallow groundwater as a water source in rapidly expanding cities. In this chapter, the pollution of shallow groundwater around Harare’s largest landfill and its largest cemetery is characterized and recommendations made for mitigating the facilities’ impacts. At each site, boreholes were drilled, groundwater sampled and chemical and microbiological analyses undertaken. The investigation at the landfill revealed typically high levels of contamination, particularly with regards to metals, nitrates and coliform bacteria. These can be related to the landfill, although activities in the suburb downflow will also have contributed. The investigation of groundwater at the cemetery established contamination with respect to some metals, nitrates, phosphate and coliform bacteria. These can be related to decomposition of bodies, and to natural hydrolysis of the aquifer rock unit. Grouting and the use of gum trees as a pressure barrier are recommended for the downflow margins of both the landfill and the cemetery. Conditions at the landfill could also be treated with locally available iron and sulphate minerals and by revegetating the top of the dump. The problems experienced at both sites relate to poor planning practices, and will be repeated in the future unless environmental and geotechnical considerations are given priority in site selection for such facilities.