During a snowstorm the fluoride feeder in North Bend runs out of feeder solution. The rapid mix tank is connected to a 5-km long distribution pipe. The flow rate into the rapid mix tank is 0.44m^3/sec, and the volume of the tank is 2.50 m^3. The velocity in the pipe is 0.17 m/sec. If the fluoride concentration in the rapid mix tank is 1.0 mg/L when the feed stops, how long until the concentration of fluoride is reduced to 0.01 mg/L at the end of the distribution pipe? The fluoride may be considered a nonreactive chemical.