CHAPTER ONE 1.1              GENERAL BACKGROUND Groundwater pollution is mainly due to the process of industrialization and urbanization that has progressively developed over time without any regard for environmental consequences. Its quality is based on the physical and chemical soluble parameters due to weathering from source rocks and anthropogenic activities. In recent times, the impact of leachate on groundwater and other water resources has attracted a lot of attention because of its overwhelming environmental significance. Leachate migration from wastes sites or landfills and the release of pollutants from sediments (under certain conditions) pose a high risk to groundwater resource if not adequately managed. Protection of groundwater is a major environmental issue since the importance of water quality on human health has attracted a great deal of interest lately. Assessing groundwater quality and developing strategies to protect aquifers from contamination are necessary for proper planning and designing water resources. Open dumps are the oldest and most common way of disposing of solid wastes, although in recent years, thousands have been closed, many are still being used. Because of these, waste management has become increasingly complex due to the increase in human population, industrial and technological revolutions and the processes that control the fate of wastes in the soil is complex and many of them are poorly understood. Issues such as nutrients release rate and other chemicals, leaching of nutrients, metals through macro pores as suspended solids and sludge organic matter on the degradation are often not understood by many.

Leaching of hydrophobic organics and fate of metals fixed by soil organic matter needed to be studied to have a better approach in handling groundwater pollution. Toxic chemicals that have high concentration of nitrate and phosphate derived from waste in the soil can filter through a dump and contaminate both ground and surface water. Insects, rodents, snakes and scavenger birds, dust, bad odour are some of the Aesthetic problems associated   with sanitary landfill.

1.2                        STATEMENT OF THE PROBLEM The problem of this study is to determine the environmental impact of leachate pollution of ground water supplies in Olukori, Ila-Orangun, Osun state 1.3                        PURPOSE OF THE STUDY The purpose of the study is to know to what extent, increase in waste generation and disposal resulted in the increase of groundwater pollution, and how it has affected the well water in Olukori area of Ila-Orangun.   1.4                        AIMS AND OBJECTIVES OF THE STUDY

1. To know the physical properties and chemical properties of the water samples in the area
2. To determine  the effect of landfill leachate in groundwater and its effect on human health

1.5                        SIGNIFICANCE OF THE STUDY Leachate migration from waste sites or landfills and the release of pollutants from sediments (under rain conditions) pose a high risk to groundwater resource, and also to human if not adequately managed.

1.6                        SCOPE OF THE STUDY This research work covers landfill leachate and how it affects groundwater supply in Olukori area. 1.7                        LIMITATION OF THE STUDY

1. Financial constraints
2. The study is limited to landfill leachate in Olukori area, Ila-Orangun
3. Time constraints
4. Lack of mobility to the area.

1.8                        DEFINITION OF TERMS GROUNDWATER: This is the water located beneath the surface of the earth’s surface in soil pore spaces and in the fractures of rock formations. LANDFILL: This is a site for the disposal of waste materials by burial, the oldest form of waste disposal. QUALITY: This refers to an attribute or a property of something POLLUTION: This is the introduction of contaminants into the natural environment that causes adverse change. LEACHATE: this is any liquid that in passing through matter, extracts solutes, suspended solids or any other components of the materials through which it has been passed.