Let’s talk chemistry The water comes downstream from the Big Cherry Lake to the water plant. Its chemical treatment begins with the addition of potassium permanganate, an oxidizer, to oxidize organic contents to avoid the formation of trihalomethanes at the final chlorination step. Then the water is treated with aluminum sulfate and sodium hydroxide as well as a polymer carrier, which three result in a precipitate (aluminum hydroxide) that adsorbs other impurities and settles down in two huge outdoor settlers. The process is followed by the gravity filtration. Those filters are backwashed and cleaned from time to time. The final step in the process is the chlorination.
The chlorination room with two big cylindrical tanks of pressurized liquid chlorine. When depressurized, the chlorine escapes as a gas and it is dissolved in the water and kills all remaining bacteria. Regular lab tests monitor the whole process that was explained to students by an employee of the Big Stone Gap Water Plant. 46