Environmental Assessment Of Potentially Oil Impacted Areas In Duburu, Khana Local Government Area, Rivers State
General Introduction
This report involves soil and surface water contamination
appraisal of five potentially impacted areas located in Khana Local Government
Area, Rivers State, Nigeria.
The area form part of the sites covered by United Nations
Environment Programme (UNEP) in 2011 and includes Duburu. Detailed descriptions
and locations of these sites are given in chapter 2.
1.2 Objective
The present assessment is required to achieve
the following objectives;
·
To
delineate the lateral and vertical extent of oil spill on soil and surface
water systems.
·
To
confirm the concentration of total petroleum hydrocarbon (TPH), polyaromatic
hydrocarbon (PAH) and volatile Compounds (BTEX)
·
Evaluate
results obtained in line with DPR regulatory standards (target and intervention
values) for contaminated surface water and soil.
·
Use data obtained to determine if remedial
measures are required for any identified affected surface soil.
1.3 Scope Of Work
The work scope for the study includes the
following:
Ø Contamination appraisal which generally
involves surface and near-surface assessment of soil.
Ø The soil survey involves an intrusive aspect
using auger drilling in which subsurface soil materials were assessed.
Ø Laboratory testing and an appraisal of the
results all in accordance with international Standards and the Department of
Petroleum Resources (DPR) Environmental Guidelines and Standards for the
Petroleum Industry in Nigeria (EGASPIN).
1.4 Environmental
Setting
Site Location, Description And Background Information
Detailed descriptions of each site together
with the location, specific characteristics and main features are summarized in
Table 1 below. A plan indicating the location of Khana L.G.A. the host local
council of all the area is included as Figure 1. The oil spill in the objective
areas occurred in January 1994 during which time the cause of the spill was
unknown. As at the time of spill, environmental media affected by free phase
oil were soils in farm lands and stagnant and running surface water. Visual
observation indicated oil sheen and oil patches on surfaces of running and
stagnant water pools and when bottom sediment is disturbed, stain on
vegetation. Areal extent of the spill as at 1994, ranged from 2 – 5km long and
20 – 140m wide, and an area of between 50,000 – 140,000m2. Average depth of penetration of free phase
oil was 0.03m, while the nearest habitation was <100m.
Fig. 1: Location map of study areas. (Not to Scale).
1.5 Limitations
and Constraints
Limitations encountered during the course of
this work were associated with the fieldwork exercise. These include challenges
associated with swampy and rugged terrains
1.6 Vegetation
Type, Local Human Activities and Land Use.
The
area is characterized mainly by secondary vegetation type characteristic of
tropical equatorial climatic regions, made up of forested evergreen plant
species composed of a mix of short shrubs medium to tall trees, short and tall
grasses and ferns in open areas, while dense vegetation and thickets made up of
tall evergreen tropical tree species and tall grasses occur around the swamp
lands. Mangrove swamps exists around water courses in the Baen area. Species of
the remnant natural vegetation include oil palm (Elaeisguineensis) and bamboo that are commonly seen in the area,
although some of the oil palm trees were planted by the local. Subsistence
agricultural activities form the main stay of the local economy of the rural
population. Annual crops cultivated by the local population include plantain,
pineapple, cassava, yam, sugarcane and maize e.t.c. Plate 1shows the vegetation
type in the spill area. A summary of the general vegetation composition in the
various sites are shown in Table 1 below:
Table 1: Site
details
|
Site |
General site
information/observations |
|
DUBURU |
Low lying, arable farm lands,
riverine, secondary vegetation |
1.7 REVIEW OF
PREVIOUS WORKS
Companies such
as shell have used a generic conceptual site model (CSM) to develop the
assessment strategy used to identify their facilities that represent a risk to
human health or the environment, and therefore require remediation. The key
findings were:
·
The main contaminant of concern is crude
oil.
·
The main primary sources of
contamination at companies operations result in discharge of crude oil to the
ground surface and where pipelines are buried to below ground.
·
There is generally a limited penetration
of crude oils into the soils in the Niger Delta. However, specific pathways may
exist that could results in deeper penetration of the contaminants.
·
Migration will predominantly be along
the ground surface from high to low topography, or through slow soil
infiltration into near surface groundwater table.
·
The main risk to human health is from
direct contact and ingestion or indirect means through the intake of
bio-accumulated forms in plant (food crops); however, there may be cases where
either potable or domestic water is impacted.
Gighi
et al(2012). Have worked onPost-impact soil assessments of crude oil spill site
in kpean community in Khana LGA (Ogoni) of rivers state, Nigeria. J. Sci., 2:
109-120.
Abstract
The environmental assessment of
potentially oil impacted areas in duburu, khana local government area, rivers
state is a research carried out on the five sites to show primary source
of contamination is considered to be the crude oil which may have either been
spilled through sabotage or leakage from the existing oil wells and pipelines resulting to the contamination of surface and
subsurface soil and water.
The oil impacted areas or spilled areas
has affected the habitant of duburu and the nearby communities;
Directly and indirectly either through consumption of harvested crops
products from the impacted areas and domestic and non-domestic animals as
food, and drinking of domestic or portable water which has been contaminated
poses to be hazardous and risky to the
human health in general, and also commercially it has made the cost of living
and standard of living high because instead of over 85% percent of foods are
bought from other communities which are not affected.
Different researches has shown
promising results and methods with
respect to remediation of oil impacted areas: s
Detailed Quantitative Risk
Assessment (DQPA), Risk Assessment Matrix, Total Petroleum Hydrocarbon (TPH), Benzene, Toluene,
Ethyle-benzene and Xylene (BTEX), e.t.c. were used for the assessmentof the
successful completion of this word.
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