4. Design an aerated grit chamber installation (2 tanks in parallel) for an average flowrate of 0.3 m^3/s and a peak flowrate of 1.0 m^3/s. The average depth is 3 m, the width-to-depth ratio is 1.5:1, and the detention time at peak flow is 3.5 min. The aeration rate is 0.4 m/min perm of the tank length. Determine the dimensions of the grit chambers and the total air required.

Fig: 1