A rapid mix unit is to treat raw water with a flow rate of 36,000 m/d. The particle horizontal velocity should vary by 4.5 m/s for every 5 mm vertical change in depth. If the retention time is 20 s, determine the tank dimensions and the power requirement for the mixer. Assume the following in your calculations: Square base for the tank Water depth = 1.3 x tank width 1.0 x 10 Pa.s Power loss in motor = 40% Power loss in shaft = 30%