Groundwater Flow and Contaminant Transport from Municipal Solid WasteDumps in Bida, Central Bida Basin, Nigeria

Abstract

In some part of Bida metropolis, the amount of solid wastes generated is on the increase due to population growth and due to the absence of modern engineered landfill. The wastes are dumped on the land surface without proper knowledge of the hydrochemistry, hydrology and geology of the dumpsites with regards to the movement of contaminants into the subsurface. The transport of contaminants from selected dumpsites into the groundwater body in Bida is the aim of this study and was undertaken by carrying out groundwater inventory studies for 130 hand dug wells identified in the area combined with sieve analysis of soil samples collected beneath the dumpsites.The groundwater inventory results revealed the average depth of wells in the area is approximately 11.0m signifying that wells in the area are shallow.The groundwater flow direction is predominantly towards the south-eastern part of the town.The flow pattern in the aquifer system therefore suggests that the eastern regions of the study area are more vulnerable to groundwater pollution with respect to differences in hydraulic heads. The maximum contaminant travel distance from the dumpsites down to the unconfined aquifer along groundwater flow directions in the hand dug wells range from 2.69 × 10-5 to 3.92 × 10-5 m.The implication of this result is that the dumpsites may pose no threat presently to the unconfined aquifer due to the low contaminant travel distances observed, but nevertheless still remain a potential threat in the nearest future. It is therefore recommended that the dumpsites conditions be improved to minimise further leachate migrations from the sites.