The average flowrate at a small municipal WWTP is $20000\frac{m^3}{d}.$ The highest observed peak daily flowrate is $50000\frac{m^3}{d}.$ Design rectangular primary clarifiers with a channel width of $6$ m $.$ Use a minimum of two clarifiers. Calculate the scour velocity, to determine if settled material will become resuspended. Estimate the BOD and TSS removal at average and peak flow. Use an overflow rate of $40\frac{m^3}{m^2}.$d at average flow and a side water depth of $4$ m $.$