Employees were cleaning a tank of Green Liquor with a fire hose. They started from outside the tank and were washing the chemicals toward the drain with a high volume of water. The Green Liquor was around the drain when two of the employees entered the tank. They were wearing chemical protective suits with knee high boots that were taped around the top. As the employees moved toward the drain, the Green Liquor flowed around behind them and rose above their boots. The Green Liquor seeped through the tape and burned the employees' legs. One employee did not require medical treatment. The second employee was hospitalized.