Groundwater contamination due to lead (Pb) migrating from Richmond municipal landfill into Matsheumhlope aquifer: evaluation of a model using field observations
M. Kubare1, C. Mutsvangwa2, and C. Masuku31WR Nyabeze and Associates, P.O. Box 863, Witkoppen, 2068, Johannesburg, South Africa 2SMV Civil Engineers, Suite 228 Postnet X9307, Polokwane, South Africa 3Department of Civil & Water Engineering, National University of Science & Technology, P.O. Box AC 939 Ascot, Bulawayo, Zimbabwe
Received: 12 Apr 2010 – Accepted for review: 07 Sep 2010 – Discussion started: 18 Oct 2010
Abstract. Disposal of solid waste in landfills is an economic option for many municipalities in developing countries where alternatives like incineration and composting are costly. However, groundwater pollution from the leachate generated within the landfill and migrating through the bottom liner material into the underlying groundwater aquifers remains a major public health concern. In our study, we evaluated the application of a mathematical model to determine the aerial extent of unacceptable groundwater contamination due to lead migrating from the Richmond landfill leachate into the underlying Matsheumhlope unconfined aquifer. A one-dimensional advection-dispersion model was applied to predict the down-gradient migration of lead into the aquifer. Linear sorption and first-order decay were considered as the dominant contaminant sink mechanisms for lead. Lead concentrations in the monitoring wells at the landfill site were used as the source term. The lead migration from the landfill was determined by water quality sampling from boreholes situated down-gradient of the landfill. The model simulations gave a good fit of the field results. The safe distance for potable water abstraction was determined to be 400 m, and the model simulations showed that the aerial extent of the pollution will increase with time. The model is most sensitive to the partition coefficient, hydraulic conductivity and longitudinal dispersivity, whilst it exhibits no sensitivity to the lead decay coefficient.
Kubare, M., Mutsvangwa, C., and Masuku, C.: Groundwater contamination due to lead (Pb) migrating from Richmond municipal landfill into Matsheumhlope aquifer: evaluation of a model using field observations, Drink. Water Eng. Sci. Discuss., 3, 251-269, doi:10.5194/dwesd-3-251-2010, 2010.