Plant Radical was one of ten huge chemical plants of the USSR. Between 1954 and 1996 it produced chlorine and caustic soda by electrolysis with mercury-pool cathode. A great deal of mercury was deposited in chlorine production buildings. The most massive mercury contamination was observed in the tank room floor and in the soil under the factory. Since 2003, cleaning and demercurization works have been taking place. The government plan is to remove about 130 000 tones mercury waste, 120 000 tones of which will be buried without reprocessing (low concentration of mercury) and 10 000 tones will be exposed to thermal demercurization (high concentration of mercury).