Question

ENVIRONMENTAL ENGINEERING CLASS

For a town with a population of 224,752 citizens, a new sanitary sewer line is being designed with an average flow rate of 85 gallons per capita per day (GPCD). Five primary clarifiers are being planned, each with a 70 ft. diameter. The residence time for the wastewater in each clarifier is 1.8 hours. What is the depth of each clarifier?

Answer 1

Population = 224,752

Average flow rate per person = 85 gallons per day

Total average flow rate = 224752x85 = 19103920 gallons per day

= 2553822.64 cubic feet per day

Peak flow rate is given by

For one clarifier flow is

Volume of sewage for one clarifier is

Cross sectional area of clarifier is

Depth of each clarifier is

= 19.87 ft = 20 ft