The hydraulic gradient of groundwater in a certain location is 2 ft/100 ft. Groundwater in this location flows through sand, with a high hydraulic conductivity equal to 40 m day-1 and a porosity of 0.5. An oil spill has caused the pollution of the groundwater in a small region beneath an industrial site. How long would it take the polluted water from that location to reach a drinking water well located 100 m down gradient? Assume no retardation of the pollutant's movement.