The August 14, 2002 release from DPC Enterprises caused 63 people from the Festus, Mo. community to seek medical evaluation. The DPC facilty repackages bulk dry liquid chlorine from tank cars into containers for industrial and municipal use in the St. Louis area.
In its final investigation report, CSB said DPC installed an unsuitable hose connecting a chlorine rail tanker to equipment at its facility. The hose braiding was made from stainless steel instead of the recommended alloy, Hastelloy C, which looks identical but is resistant to chlorine. While a supplier had furnished DPC with an improper hose, investigators said DPC lacked effective management systems to prevent such a hose from being placed in service.
CSB called on both DPC and its hose supplier, Branham Corp., to improve quality assurance programs and make sure that hoses are made from the correct materials. The board also recommended that chlorine and hose manufacturing companies develop an industry-wide system for positive identification of hoses.
The board also found that DPC lacked an effective testing and inspection program for its chlorine emergency shutdown system. Emergency shutdown valves failed to close properly once the chlorine lead had begun, extending the duration and severity of the release. Investigators found that the valves were inoperable duet internal system corrosion, in turn caused by inadvertent introduction of moisture into the chlorine system.
CSB also recommended improvements to emergency response and community notification systems. The report found a lack of adequate planning and training for a major release. Emergency breathing equipment stored at the plant became inaccessible once the leak had begun. It took three hours for personnel in protective suits to reach the rail car and close manual valves cutting off the flow of chlorine. By then, more than half the contents of the tanker had been released.
The final report of the board will be available later this month on the agency's Web site, http://www.csb.gov.