A water treatment plant has a flowrate of 40,000 m3/d. If the overflow rate is 25 m3/d/m2, determine the following:
a. The length and width of the settling tanks (two rectangular units are desired with a length to width ratio of 3:1). Assume the average depth of the tank is 4m.
b. The weir length of each tank if the weir loading is 125 m3/d/m.
c. The detention time of the settling tank.