A wastewater is to be disinfected with 35 mg/L of chlorine to obtain 99% kill of microorganisms. The number of microorganisms remaining alive (N_t) at time t, is modelled by N_t = N₀e^-kt, where N₀ is number of microorganisms at t = 0, and k is the rate of kill. The wastewater flow rate is 36 m³/h, and k = 0.23 min^-1. If the depth and width of the chlorination tank are 1.5 m and 1.0 m, respectively, the length of the tank (in m, round off to 2 decimal places) is _______.