TABLE OF CONTENTs
Title page ……………………………………………………………………………………...………i
Dedication …………………………………………………………………………………….……...ii
Acknowledgement …………………………………………………………………………………..iii
Table of content ………………………………………………………………………………….…..iv
CHAPTER ONE: INTRODUCTION
1.1 Brief history of SIWES ……………………………………………………………………...……….1
CHAPTER TWO:
2.1 Company profile ……………………………………………………..……………………………..10
2.2 Brief history of the company
2.3 Department of the company
CHAPTER THREE
3.1 Groundwater and groundwater exploration ………………………..………………………………11
3.2 Ground water
3.2.1 Introduction
3.3 Ground water exploration
CHAPTER FOUR
4.1 Activity ………………………………………………………………………………………..........13
4.1.1 Subsurface investigation
4.2 Process and Result
4.3 Report of pre-drilling feasibility/geophysical investigation or ground water exploration
CHAPTER FIVE
5.1 Summary …………………………………………………………………………………………....21
5.2 Main activities of the company
5.3 Benefits and Challenges
5.4 Recommendation
5.5 Lesson/skills acquired
CHAPTER SIX: CONCLUSION …………………………………………………………………24
INTRODUCTION
Water is life. There is no gain saying that without water there would be no life of any kind on earth. Apart from air, it is the most important. It sustains human life and constitutes about 70% of its weight .It tremendous use and advantage is worth of note in domestic, industrial, agriculture, navigational and recreation sectors as well as energy in form of hydropower generation.
Although water is about 70% (by volume) of potable water supply is through underground water exploitation (wells, boreholes, tube wells wash bore). This is so because the unit cost of providing and sustaining water through well is less. In addition to this, the underground water is pure, natural and free from contamination. It does not require treatments (addition of additive such as chlorine, potassium, alum and others) which have been proved to have their cumulative effect on the body chemistry.
Groundwater exploration is gaining more and more importance in Nigeria owning to the ever increasing demand for water supplies, especially in areas with inadequate surface water supplies. Already, ten percent of the world’s population is affected by chronic water scarcity and this is likely to rise to one-third by about 2025 (WHO, 1996). The waters carcity experienced by the people, led to the search for surface water supply.
Surface water, which mostly occurs as rivers are subjected to pollution. It is sad to say that most of the rivers in Nigeria are highly polluted, the pollutants being inadvertently introduced by man via industrial and petroleum exploration activities. Despite the reported favorable ground water situations the world over, the Nigeria situation appears to be restricted by the fact that more than half of the country is underlain by sedimentary formations. These rocks comprise mainly sand stones, shales, clays and hard crystalline impervious rocks which are either igneous and limestone (Offodile, 1983).
The first alternative opened to man is ground water, which may be defined as “water in the zone of saturation and from which wells, springs and underground run off are supplied”. This water is trapped by geological formations (Palacky et al., 1981). Many dug wells that were sunk in the study area without an initial proper investigation failed and so were abandoned.
There are several reasons for the failure of boreholes and these include inadequate or lack of pre drilling investigation, lack of expertise on the part of personnel handling the drilling and sometimes lack of proper development of a successfully dug hole.
Hence, a systematic and scientific approach to the problem is therefore essential for the study area in order to overcome these problems.
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called water table. Groundwater is often withdrawn for agricultural, municipal and industrial use by constructing and operating extraction wells. Groundwater is also widely used as a source, for drinking supply and irrigation in food production (Zekster and Everett, 2004). Naturally, 53% of all population relies on groundwater as a source of drinking water. In rural areas the figure is higher. Basically, Lagos which is the study area located in the south-west region of Nigeria with dense population living along the coast have a problem with inhabitants gaining access to groundwater at the same depth.
GROUND WATER EXPLORATION
Electrical resistivity method of geophysical techniques happens to be the most preferred method in groundwater potential.
Vertical Electrical Sounding (VES) is a geoelectrical common method to measure vertical alterations of electrical resistivity. The method has been recognized to be more suitable for hydro geological survey of sedimentary basin (Kelly and Stanislav, 1993).
The electrical resistivity technique involves the measurement of the apparent resistivity of soils and rock as a function of depth or position. The most common electrical technique needed in hydro geologic and environmental investigations is vertical electrical soundings (resistivity sounding). During resistivity surveys, current is injected into the Earth through a pair of current electrodes, and the potential difference is measured between a pair of potential electrodes. The current and potential electrodes are generally arranged in a linear array. Common arrays include dipole-dipole array, pole-pole array, Schlumberger array and the Wenner array. The bulk average resistivity of all soils and rock influencing the current. It is calculated by dividing the measured potential difference by the input current and multiplying by a geometric factor specific to the array being used and electrode spacing.
In a resistivity sounding, the distance between the current electrodes and the potential electrodes is systematically increased, thereby yielding information on subsurface resistivity from successively greater depth. The variation of resistivity with the depth is modeled using forward and inverse modeling computer software.