GEOELECTRICAL RESISTIVITY OF SOLDER WASTE IN ELIOZU OBIO-AKPOR LOCAL GOVERNMENT AREA OF RIVER STATE
ABSTRACT: Electrical geophysical survey utilizing two dimensional and one-dimensional resistivity survey was carried out on Eliozu dumpsite that has been closed from operation since December 2019 in Obio/Akporn Local Government Area of Rivers State, South – Southern Nigeria. The aim was to map the solder waste plume and extent of migration in the subsurface for possible groundwater contamination. The geoelectrical survey was carried out using Abem SAS 300C Terrameter model resistivity meter with Wenner array and Schlumberger configuration of electrode spacing. A total of six (6) 2-D resistivity profiles with length 120m were conducted for Wenner and for Schlumberger; MN = 20m and AB = 360m within the dumpsite. A control profile of the 2D resistivity survey was also carried out at about 300 m away from the dumpsite. The obtained resistivity data was interpreted using Zond-1D and 2D respectively.
Keywords: Closed Dumpsite, Profile, Resistivity, Solder Waste, Waste Plume
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CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Wastes are materials that are products of human industrial or developmental activity or process but have no immediate economic value or demand and must be discarded, have been managed in a manner that has made the quest of the government to positively actualize the megacity status a difficult task. In the environment, like in most other environs and cities, wastes are generated daily and most of the wastes are discarded in improperly situated and dumping sites that are not engineered. Most of the dumping sites are located within residential environs, markets, farms, roadsides, and others. This threatens the groundwater and road facilities, not sparing the aesthetics of such affected environs. Unarguably, uncontrolled citing of boreholes as the source of potable water in most of our urban and rural communities as the government seemingly no longer provides the populace with water has become a serious challenge. However, maintaining a portable groundwater supply that is free from microbial and chemical contaminants is far from reality in most of our urban centers, and in particular Port Harcourt municipality, due to poor waste disposal and management practices. The challenge is worsened by the fact that there are inadequately trained waste disposal personnel and equipment, poor waste collection, sorting and disposal methods, and indiscriminate location of disposal sites without regard to the local geology and hydrogeology of the environ. All these contribute significantly to the contamination of soil and groundwater. Recent industrial development and increased urbanization in the municipality have resulted in an enormous generation of all kinds of waste ranging from municipal to industrial. The type of waste generated varies widely with many human activities located close to dumpsites. Industrial wastes are generated from industrial activities such as chemicals, pesticides, paints, grease, inorganic materials, oil sludge, etc. while domestic wastes are those generated from commercial establishments and household activities. They occur in different forms, waterborne waste from households, including sewage, human and animal remains as well as chemical and laboratory waste. The release of these materials into the environment sometimes causes serious health problems. The level of wastes produced by dense human and domestic animal populations often exceeds the local ecosystem’s biodegradability, resulting in serious environmental pollution and epidemic outbreaks of diseases (Ronald, 1988). During the peak of the rainy season, the dumpsite is covered by floodwater and this contributes to the formation of leachate. It is this contaminated liquid that enters into the soil and also eventually into the underlying groundwater at such dumpsites. The manner of disposal points to the fact that solid waste management is one of the greatest challenges facing state and local government environmental protection agencies in Rivers State. In view of the foregoing, this study was embarked upon to establish the adverse effect potentials of the wastes at the dumpsite on the groundwater systems of the environment. The major source of groundwater contamination in the municipality is the solid waste landfill. Others are improperly functioning septic tank systems, hydrocarbons, and industrial chemicals. Solid waste landfills (SWL) have become a popular waste management system for the disposal of all manner of waste materials in the municipality. They are usually abandoned or disused exhumed pits used for road construction, and are, therefore, not engineered for the containment of landfill emissions into the environment. As a result of the imminent impact of solid waste landfills, it has become necessary to investigate the potential for the contamination of soil and groundwater around a municipal solid waste landfill. In this work, the electrical resistivity method was used in line with Benson et. al. (1983), Mathias et. al. (1994) and kayabali et. al. (1998) to investigate the effect of the waste on the soil and groundwater in the dumpsite environ. The main objective of this study is to detect the solder plume zone in the closed dumpsite environment and delineate the depth and extent of contamination caused by the opened waste disposal site. The use of two dimensional and one-dimensional resistivity survey method will present detailed information about contaminated solder zones and evaluate its effect on groundwater around the closed dumpsite environs.
1.1 Statement of Problem
It has been postulated that the cause of the third world war could be water (Gore, 1992). Following this postulation, it, therefore, means that the inadequate amount of freshwater sources and the lack of it will lead nations against each other. In most parts of Rivers State, the reliance on open dumpsite is a common phenomenon in the disposal of waste materials. However, literature is sparse on the impact of these closed dumpsites and evaluations on the environs. In view of this fact, this study, therefore, will focus on the effects of solder waste plumes on the environs in Elioz, Obio/Akpor Local Government Area of Rivers State of Nigeria.
1.3 Aim and Objectives
The primary aim of this research is to use two dimensional and one-dimensional electrical resistivity techniques to study solder waste and the potential impact on human health and the environment. The specific research objectives set out include:
- To determine the subsurface geo-electric formations.
- To determine the depth to solder waste plume.
- Lithology delineation of the subsurface.
- To detect and map solder waste plume zones.
1.4 Justification
A dumpsite be it active or inactive it is a reception of all kinds of wastes. Thus, solid, liquid and gaseous wastes are dumped or discharged into the dumpsite, which could affect soil, groundwater, and environment. The challenge needs attention due to the fact that there are inadequately trained waste disposal personnel and equipment, poor waste collection, sorting and disposal methods, and location of this disposal site without regard to the local geology and hydrogeology of the area (Jatauand Ajodo, 2006). As a result of the imminent impact of solid waste on the environment, it has become necessary to investigate and evaluate the solder waste plumes of Elioz closed dumpsite and environs.
1.5 Scope of the Study
The Scope of this research is limited to the following:
- Conduct a surface geophysical prospecting (1D & 2D Imagery) for solder waste plumes.
- Deduce the geophysical models and anomalies of the closed dumpsite
- Estimate the reserve based on prospect analysis
- Make recommendations and contributions to knowledge about the closed dumpsite.
1.6 Description of the Study Environment
1.6.1 Location
The Closed dumpsite is located in Elioz in Obio Akpor Local Government Area, Rivers State. It is delineated between Latitude 4°51’45.83″N and 4°55’30.12″N and longitudes 6°59’45.68″E and 7° 5’58.90″E (Figure 1) within the Rivers State of Nigeria.
Figure 1: Study Location Map showing VES and HRP survey Points
1.6.2 Accessibility
The dumpsite is about 0.22 km away from G.U Ake Road formerly known as Olu-Obasanjo By-pass (Eliozu) and 2.72 km away from Rumuokoro junction. Figure 1 is the map of Obio/Akpor Local Government Area indicating the study area. The dumpsite is about 0.22 km away from G.U Ake Road formerly known as Olu-Obasanjo By-pass (Eliozu) and 2.72 km away from Rumuokoro junction. Figure 1 is the map of Obio/Akpor Local Government Area indicating the study area.
The dumpsite is about 0.22 km away from G.U Ake Road formerly known as Olu-Obasanjo By-pass (Elioz) and 2.72 km away from Rumuokoro junction. Figure 1 is the map of Obio/Akpor Local Government Area indicating the study area.
1.6.3 Topography and Drainage
Relief could be defined as the undulating nature of a place, that is, the high and low lands that characterize a place. Drainage, on the other hand, can be said to be the embodiment of water bodies such as lakes, streams, rivers, etc which are present in a place (Oyegun, 2014).The relief of Port Harcourt city to which Obio-Akpor is a part of falls within the Niger Delta relief system, one of the seven relief systems of Nigeria. Generally, the land surface of Rivers state slopes gently in the North West (NW) and South East (SE) direction. The state’s northern quadrants characteristically have planes rolling gently. The entire relief is made up of sand bars and coastal plains that are rolling gently. The drainage of the area is controlled structurally by the shore zone dendritic pattern of the lowland of the coast, in which its tributaries branches irregularly at any angle in any direction. The pattern of the network in the area does not exactly fit into the trellised drainage pattern neither does it fit into the dendritic pattern either. The numerous rivers in the study area, all empty into the Atlantic Ocean (Oyegun & Adeyemo 1999).The entrance to the creek and system of the river, for example, the Bonny and the New Calabar river systems allow the river to empty their waters into the Atlantic ocean and serves as inlets of large quantities of ocean wide and there is very wide intertidal flat traversed by several creeks (Oyegun & Adeyemo 1999).
1.6.4 Climate and Vegetation
Eliozu belongs to the Niger Delta area portraying tropical rainforest climate, with a distinct wet (April – October) and dry (November – March) seasons. The mean annual rainfall ranges from 2000mm (inland) to over 4000mm at the coast and the area is characterized by five major geomorphic units namely dry flatland & plains, Sombreiro -Warri deltaic plains with abundant freshwater back swamps, freshwater swamps, meander belts & alluvial swamps, saltwater or mangrove swamp and active/abandoned coastal ridges (Akpokodje, 2001).
1.6.5 Geology of the Study Area
The Study area geology is not different from the general geology of the Niger Delta Basin, which is geologically composed of various Quaternary deposits that overlie the three main stratigraphic units of Benin, Agbada and Akata. The Benin Formation (Oligocene to Recent) is the aquiferous formation in the study area and is exploited for groundwater supplies (Akpokodje, 2001). Although a depth of 100m is most exploited, about 300m depth has been exploited for water (Ngah, 1990). The Benin Formation consists essentially of massive and highly porous sands and gravels with a few thin clay intercalations. The uppermost section of the Benin Formation is the Quaternary deposits of about 40- 150m thick and comprises of rapidly alternating sequences of sand and silt/clay with the later becoming increasingly more prominent seawards (Etu-Efeotor and Akpokodje, 1990).
1.6.6 Hydro-geology of Study Area
The major aquiferous formation in the study area is the Benin Formation. It is about 2100 m thick at the basin center and consists of coarse-medium grained sandstones, thick shales, and gravels. The upper section of the Benin Formation is the quaternary deposits which are about 40 150 m thick and comprise of sand and silt/clay with the later becoming increasingly more prominent seawards (Etu-Efeotor & Akpokodje, 1990). The formation consists of predominantly freshwater continental friable sands and gravel that have excellent aquifer properties with occasional intercalations of claystone/shales (Olobaniyi & Oweyemi, 2006). According to Etu-Efeotor (1981), Etu-Efeotor & Akpokodje (1990), Offodile (2002), Udom et al. (2002), the Benin Formation is highly permeable, prolific, productive and is the most extensively tapped aquifer in the Niger Delta. All the boreholes in the study area were drilled into it. The Benin Formation consists of fluvial and lacustrine deposits whose thicknesses are variable but generally exceed 1970 meters (Asseez, 1989). According to Onyeagocha (1980), the rocks of the Benin Formation are made up of about 95 99% quartz grains, Na+K Mica 1 -2.5%, feldspar 0.5 1.0% and dark minerals 2.3%. These minerals are loosely bound by calcite and silica cement. The clayey intercalations have given rise to multiaquifer systems in the area. The main source of recharge is through direct precipitation where annual rainfall is as high as 2000 2400 mm. The water infiltrates through the highly permeable sands of the Benin Formation to recharge the aquifers. Groundwater in the study area occurs principally under water table conditions. Multi-aquifer systems occur in the study area and the upper aquifers are generally unconfined (Etu-Efeotor, 1981; Offodile, 2002; Edet, 1993; and Udom, 2004).
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