Environmental Engineering Reference
In-Depth Information
CHAPTER 7
Impacts of a solid waste disposal site and a
cemetery on groundwater quality in Harare,
Zimbabwe
W. Moyce, D. Love, K. Musiwa, Z. Nyama, P. Mangeya, S. Ravengai, M.
Wuta & E. Zingoni
ABSTRACT: 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.
1 INTRODUCTION
1.1
Objectives of this study
In the City of Harare, Zimbabwe, there is a widespread small-scale use of shallow
groundwater by industrial and private residential establishments. Research in some parts
of Harare has shown that such shallow groundwater is polluted (Hranova et al. 2003,
Ravengai & Love 2004, Zingoni et al. 2004). At the same time, Harare is rapidly
