The settling velocity of calcium carbonate floc formed during flocculation in a floccula...

The settling velocity of calcium carbonate floc formed during flocculation in a flocculator-clarifier (Figure 7-10) is 2.1 mm/s. If the detention time in the settling zone is 1.0 hr and upflow rate is 1.75 gpm/sq ft, what is the minimum depth of water required to ensure removal of the floc by gravity settling?