الفهرس 
OBJECTIVES OF THE STUDYOnly 14 pages are availabe for public view
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Abstract
Groundwater is an important source of fresh water. However, human activities threaten quality of groundwater. Solid waste landfill and septic tanks are considered the most common sources of groundwater contaminations, where landfill leachate and water with virus and bacteria are infiltrate into ground toward groundwater. Control of groundwater contamination is very important. Hydraulic control of groundwater movement is considered adequate solution, which help in minimizing groundwater contamination. Unequal double sheet piles with solid floor were used to delay contamination arrival downstream the structure. Numerical model (Geo-Studio), which bases on Finite Element Method (FEM) and includes many modules like (SEEP/W) and (C/TRAN), was used to solve contamination distribution through groundwater. The module (SEEP/W) solves groundwater motion and the module (C/TRAN) solves contamination distribution with the aid of results of (SEEP/W). The study includes solute transport by advection and diffusion processes together and advection process only. Analytical solutions and experimental work using a sand box model were used to validate results of the numerical model. Arrival times of contaminations below the two sheet piles and downstream the structure were listed according to different parameter as sheet piles depth, distance between first sheet pile and contamination source, solid floor length, hydraulic conductivity, and head difference between upstream and downstream. Comparison between experimental and numerical results was performed. Numerical model results are trusted as Validation of numerical model clears that errors percentage didn’t exceed 5.81% for ground water movement. Numerical model can be used to study similar problems as a comparison between experimental and numerical results shows that errors percentage didn’t exceed 9.2% for the investigated cases. Depths of unequal double sheet pile, distance between contamination source and first sheet pile, and hydraulic conductivity have significant effect on contamination spread. It was concluded that practical configuration of the two sheet piles depths as following, for relative depth of the 1st sheet pile (d1/D) ≥ 0.15 depth of the 1st sheet pile should be longer than depth of the 2nd sheet pile. For d1/D ≤ 0.15 and higher values of relative distance between contaminations source and the 1st sheet pile (Ls/D) relative depth of the 2nd sheet pile should be around 0.6. Increasing the head difference between U.S and D.S of the structure led to decrease arrival time. When Distance between the contamination source and the 1st sheet pile increased, arrival time downstream the structure increased for Advection-dispersion analysis. Arrival time had a minimum value at a certain Ls/D and increased closer and farther for Particle tracking analysis depending on the configuration of the depths of the two sheet piles and the length of the solid floor. Dimensionless charts, Formulae, and Tables were presented to help in designing of hydraulic control system and evaluation of primary cost.