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:
 Contamination appraisal which generally involves surface and near-surface assessment of soil.
 The soil survey involves an intrusive aspect using auger drilling in which subsurface soil materials were assessed.
 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.