Design a grit chamber for a wastewater treatment plant with an average flow rate of 25,000 m3/d and a peak flow rate of 55,000 m3/d. The detention time at peak flow is 3.0 min. The width to depth ratio is 2:1. Use a depth of 2 m. The aeratiDesign a grit chamber for a wastewater treatment plant with an average flow rate of 25,000 m3/d and a peak flow rate of 55,000 m3/d. The detention time at peak flow is 3.0 min. The width to depth ratio is 2:1. Use a depth of 2 m. The aeration rate is 0.4 m3/min per m of tank length. Determine the total air required and dimensions of the grit chamber.on rate is 0.4 m3/min per m of tank length. Determine the total air required and dimensions of the grit chamber.