Railroad tank car is derailed and ruptured. it discharges 380 m3of pesticide into the mud lake drain. the drain flows into mud lake which has a liquid volume of 40,000 m3. the water in the creek has a flow rate of 0.10 m3/s, a velocity of 0.10 m/s, and the distance from the spill site to the pond is 20 km. assume that the spill is short enough to treat the injection of the pesticide as a pulse, that the pond behaves as a flow balancedcstr, and that the pesticide is nonreactive. estimate the time it will take to flush 99 percent of the pesticide from the pond.