Question

6. There are five identical circular primary sedimentation tanks (in parallel) to be installed at a POTW. The average plant influent flow rate is 30 MGD, and the peaking factor

is 2.5. The design surface overflow rates are 1,000 and 1,500 gpd/ft? for the average flow and the peak flow, respectively. a) Determine the required total area of these primary sedimentation tanks under average flow b) Determine the required total area of these primary sedimentation tanks under peak flow c) Determine the design diameter of these primary sedimentation tanks at this facility d) If the water depth is 12 ft, what is the hydraulic detention time under the peak flow condition?

Fig: 1

Fig: 2

Fig: 3

Fig: 4

Fig: 5