1. [20 points] A 1800ft3 sedimentation tank with a water depth of 12 feet is used to remove sand particles from water by settling. The specific gravity of the sand particles is 2.65 and the diameter of the particles is 0.001cm. The temperature of the water is 60F(15.6C). Adjust both the kinematic viscosity and the density of water accordingly. a. Calculate the settling velocity (m/hr). [10 points] b. Assuming this settling velocity is the overflow rate, calculate the hydraulic residence time (hr) [5 points]