An experiment on soil venting is being planned in a large lysimeter (an unsaturated soil column) 4 m in height and 2.5 m in diameter. The soil has an average grain diameter dg =127 µm, and gas flow...

An experiment on soil venting is being planned in a large lysimeter (an unsaturated soil column) 4 m in height and 2.5 m in diameter. The soil has an average grain diameter dg =127 µm, and gas flow rates of Q = 0.6 m 3 min -1 are planned. The soil has 10% water and 10% TCE saturation with a total soil porosity of 0.40. (a) For these conditions, what distance will be necessary to reach an air concentration of TCE of 95% saturation? (b) Assuming the chemical volatilization rate calculated in part (a) is constant, how long will it take to volatilize all the TCE over that length of air flow? (c) Calculate the number of pore volumes of air for part (b). (d) If TCE is present over a much smaller distance of 30 cm, calculate the concentration of TCE in the air. (e) How long will it take to volatilize the TCE in part (d)?