Times Beach, Missouri Dioxin contamination and a controversial clean-up operation

An overview  Times Beach is a small town in South-western Missouri.  Between 1970 and 1972, large amounts of hexachlorophene were produced by a pharmaceutical and chemical company.  The resulting waste from this production contained TCDD.  This waste was then mixed with oil and sprayed along the roads in Times Beach in an effort to control dust.

Continued …  Soon after the chemical was sprayed along roads, animals died and children fell sick.  In 1982 soil tests found that the town was being poisoned by dioxin.  Over 500 families were told to evacuate their homes while additional tests were carried out.

The Chosen Solution …  On site Incineration.  Contaminated soil was shredded, screened and treated with lime.  Incineration system comprised of a primary chamber, secondary combustion chamber and thermal relief vent.

Primary Chamber

Description  Consists of a rotary kiln.  Contaminated soil is feed into kiln and the dioxins are burnt.  Ash is discharged at lower end of kiln.  Flue gases from the kiln are passed on to the Secondary Combustion Chamber for complete destruction.

Rotary kiln with secondary combustion chamber

Secondary Combustion Chamber  Vertical refractory lined vessel which heats the flue gas to complete combustion.  Heats the vaporized dioxins until they are completely vaporised.

Thermal Relief Vent  Attached vessel at the top of the secondary combustion chamber.  Dissipates positive pressure incase if failure of the draft fans.

Conclusion  The use of an incinerator was a controversial decision.  On March 20, 1990, an electrical power-cut caused a discharge of dioxin-contaminated pollutants.  Different groups formed opposing the incinerator.  The experience at Times beach has led to new laws regarding chemical waste disposal.