Question

Design a horizontal flow grit chamber to remove grit (SG = 2.5) of size 0.2 mm and larger for a water temperature of 20°C. The average daily flow rate is 2.227 MGD. The chamber should be designed to treat the peak hourly flow. The flow peaking factor (i.e., ratio of peak hourly to average daily) is 2.5. Use a ratio of tank depth to width of 1.25. Use a safety factor of 1.35 (i.e., Adplan = Aplan ́ 1.35). Make sure that the design will provide for scour of organic particles (assume 0.2 mm, SG=1.1) but not the grit particles. For the scour calculations, use b = 0.05, f = 0.025. Give tank dimensions in ft and round up to the nearest ft. What is the residence time (in min)?

Answer 1