An activated sludge aeration basin is a rectangular tank 120 ft long × 60 ft wide with a water depth (SWD) of 15 ft. The basin has 2 ft of freeboard (do not include freeboard in liquid volume). Average flow to the aeration basin is 2.4 MGD. Current MLSS is 2,800 mg/L and SVI is 140 mL/g. Using 1 ft³ = 7.48 gal and 1 day = 24 hr, what is the theoretical detention time in the aeration basin (hours)?