Journal of American Science 2010;6(9) 247 Controlling Contaminated Fluid from Polluting Groundwater using Porous Media. 1 O.I. Popoola , 1 J.A. Adegoke, 2 O.O. Alabi, 3* F.O. Akinluyi, and 2 K.A. Fayemiwo 1 Deparment of Physics, University of Ibadan, 211001, Nigeria. 2 College of Science, Engineering and Technology, Osun State University, Osogbo, 230001, Nigeria. 3 Physics Department, Adeyemi College of Education, 351001, Nigeria. Akinluyi18370@alumni.itc.nl , iopopoola@yahoo.com , adegokeja@yahoo.com , geosciencealabi@yahoo.com , akinluyi18370@alumni.itc.nl , kfayemiwo@yahoo.ca Abstract: The study of movement of underground water helps to predict the flow of contaminated fluid from a solid waste landfill into a portable water supply. Sand samples from river bed were used as stratified porous media and a laboratory experiment was set up to look at the deflection pattern in term of volume of liquid flowing across a unit cross-sectional area per unit time at different angles. Water was made to flow through the inlet and outlet pipes filled with sands of different porosities and the volume of water discharge was determined by volumetric method. A graph of cosine of angle of deflection against porosity ratio gives a relation cos θ = 1.98ln r φ + 1.13. With this established equation, a stratified porous media of known porosity ratio can be used to control the direction of contaminated fluid in sub-surface layer. [Journal of American Science 2010;6(9):247- 255]. (ISSN: 1545-1003). Key words: porosity, inclination angle, volume flux, deflection, outlet angle 1. Introduction There are three major wastewater disposed techniques. They are treatment and discharge into surface waters, treatment and reuse and land disposal via septic tanks and spray irrigation (Henry, 2003). Major consideration will be given to land disposal of sewage in this study. The major factor influencing the suitability of the soil for filter field use is the water-saturated hydraulic conductivity. Sewage effluent may move so rapidly in high hydraulic conductivity sand and disease organisms are not destroyed before shallow- water supplies become contaminated. Soils with low hydraulic conductivity are not suited for septic drain fields, because the sewage effluent may saturate soil and contaminate the surface soil (Henry, 2003). Thus, there is a need to seek for better or suitable soil filter for the field. Heterogeneous medium is used as protective filter and drainage control medium, for example when a small amount of clay is mixed with sand in man- made constructions (Sower and Sower, 1970 and Cedergreen, 1976). However, it has been observed that under the same hydraulic gradient, layered (stratified) heterogeneous medium serves better than mixed heterogeneous medium (Popoola et al, 2008). In another experiment, it was observed that layered heterogeneous medium arranged in descending order of porosity from bottom serves better and gives the relationship between maximum volume flux (or specific discharge) q max and porosity ratio φ r as q max = 37.89 r φ -18.39 (Popoola et al, 2008) The purpose of this work is to device a means to deflect the sewage effluent from the direction of water supplies by using layered (or stratified) heterogeneous medium by establishing the relationship between angle of deflection (θ) and porosity ratio which can be used to control the direction of flow of contaminated fluid or sewage effluent in sub-surface groundwater. 2. Theoretical Background When streamlines from a medium of a given hydraulic conductivity K 1 cross the boundary of a medium with different hydraulic conductivity K 2 , they are refracted in a manner similar to optical refraction of light rays. The refraction follows the law 2 2 1 1 tan tan θ θ k k = (1) ( Casagrande, 1937 and Cedergreen, 1976) where θ 1 = angle between the normal line and the incident line in medium of hydraulic conductivity K, and θ 2 = angle between the normal line and the refraction line in medium of hydraulic conductivity K 2 The flow lines deflect to conform to equation