A non reactive/conservative contaminant is dumped on the ground level and it leaches to the groundwater vertically and takes half day for reaching the groundwater by travelling through unsaturated zone. The contaminant can have adverse health effects on humans. The groundwater flowing from left to right due to the hydraulic gradient and there is a human settlement at 5 km distance from the contaminant dumping site. The water table level at the dumping site is at 5 m from the groundlevel. The terrain has a slope of 10 m vertical per km horizontal. The water table at the settlement is 15 m from the groundlevel. The soil sample analysis of a in situ sample for 100 cm given the volume of voids as 40 cm. Assume the horizontal impervious layer which can be used as a datum at 100 m below groundlevel from the ground of the dumping site. If the settlement has to be evacuated 10 years before the contaminant reaches it how many years from present year the evacuation should be completed. Please use rounding off for years as per convenience. 8 Marks The hydraulic conductivity of the aquifer is 10 m/d.