Abstract:
The subsurface soil around Baruwa community was reportedly contaminated by hydrocarbon not because the
area falls within oil-producing community but it suffers from inceasant leakage from petroleum pipeline that
supply petroleum products to hydrocarbon terminar located within the area. Thus, to ascretain the extent of
contamination of the subsurface soil around the area, an integrated geophysical methods involving vertical
electrical sounding (VES) and electrical resistivity tomography (ERT) supported with induced polarization (IP)
and spontaneous potential (SP) methods were carried out. The hydrocarbon contaminated layers were marked
out beneath each VES point by high resistivity ranging between 943Ωm and 4749Ωm at a depth of 1 to 35.44m
below the surface. Similarly, ERT result shows that the subsurface soil around the investigated area has been
contaminated at a shallow depth of about 2m downward with resistivity value above 1000Ωm. IP and SP data
were Integrated to identify the sandy contaminated layers from clayey layer. IP value of 0 to 10mV/V and SP
values of <+10mV were obtained over the sandy formation. The work shows that hydrocarbon leaking from the
pipeline laid a few meters beneath the earth surface actually flow both upwardly (possibly due to seasonal
variation in the water table which is usually close to the surface during rainy season) to the surface and
downwardly at greater depth into the subsurface, through a porous medium - sandy layer. This may probably
accounts for the reason while most of the handdug wells in the area are reportedly contaminated with
hydrocarbon products.
