Assessing Groundwater Vulnerability to the Activities of Artisanal Refining in Bolo and Environs, Ogu/Bolo Local Government Area of Rivers State; Nigeria.
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Date
2012-01
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Abstract
Artisanal refining typically involves primitive illegal stills in which crude oil is boiled and
the resultant fumes are collected, cooled and condensed in tanks to be used locally for
lighting, energy or transport. The distilleries are heated on open fires fed by crude oil that
is tipped into pits in the ground. As part of the oil burns away, some seeps into the
ground. The waste from the process is stored in open pits thereby increasing the risk of
the contamination of the environment and possibly impacting the underground aquifer. It
is this concern of crude oil seeping to the groundwater that necessitated the current
investigation with the sole objective of assessing the vulnerability of the aquifer to the
activities of artisanal refining. Soil, water and crude oil samples from artisanal refining
sites were collected according to standard procedures and transferred to the laboratory
for analyses to determine their properties.
An empirical method was adopted in estimating the permeability. The Kozeny – Carman
equation for deriving the coefficient of permeability takes the porosity (η) into account.
Using a typical soil porosity η = 0.4, mean particle size = 0.05 and mean viscosity
determined from crude samples permeability estimate was calculated to be 3.6 x 10-
8cm/s, infiltration was assessed using a simplified version of Darcy’s law. With a typical
superficial soil permeability of 3.6 x 10-8 cm/s, depth of ponding of 0.5m, and a wetting
front of 0.4m, an estimated infiltration rate of 1.15 x 10-8cm/s can be expected. Given the
infiltration rate and the depth to groundwater (water table is between 3m and 8m), we
calculated the time for crude oil contaminant plume to intercept the water table simply reexpressing
the equation for velocity as distance/time which results in approximately 4.6
years. The character of the water from the area indicates that groundwater is already being impacted given that artisanal refining has been going on in the area since 2002.
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Keywords
Artisanal refining, groundwater, infiltration, permeability, vulnerability, aquifer, pollution
Citation
Amangabara Gordon T, Njoku John D. Assessing Groundwater Vulnerability to the Activities of Artisanal Refining in Bolo and Environs, Ogu/Bolo Local Government Area of Rivers State; Nigeria. British Journal of Environment and Climate Change. 2012 Jan-Mar; 2(1): 28-36.