Abstract:
Water quality degradation is one of the major environmental problems in Addis Ababa and
municipal solid waste disposal sites can be sources of groundwater contamination as leachate
may infiltrate and join the aquifer. In Addis Ababa, there is currently one landfill site at Repi
in the South West of the city located 13kms away from the city center. The Repi landfill site
was commissioned more than 40 years ago and the only factors that were considered in
selecting this site were hauling distance and availability of the land. Geophysical surveys,
involving 2-D resistivity imaging and vertical electrical sounding were conducted around the
solid waste landfill for a hydro-geophysical assessment of contamination of groundwater.
IRIS SYSCAL R1 Plus switch-72 multinode imaging unit was used to acquire data both for
the imaging and VES survey. In general 3 traverses for imaging and 3 VES measurement
points along a profile were used for the study.
The correlation between the 2-D resistivity imaging and the VES data is outstanding. The
results clearly indicate that the underlying layers in this area around the landfill are weak
incapable of preventing downward movement of the leachate from the landfill to the
groundwater. Hence, the groundwater in this area may have been contaminated. Therefore,
the usage of the landfill which is without geologically impermeable ground must be
discouraged. It is also strongly recommended that a thorough study of any site must be done
before any operation so as to know whether the aquifer is naturally sealed or not.
Keywords: 2-D resistivity imaging, VES, solid waste landfill, lecahate, chemical waste and
groundwater.