July 20, 2023

CSB Urges EPA, OSHA to Close Regulatory Gap in Explosion Report

In its final report on a fatal 2020 explosion (PDF), the U.S. Chemical Safety and Hazard Investigation Board has repeated its long-standing recommendation that EPA and OSHA adopt standards addressing reactive chemicals and hazards. While companies Optima Belle LLC and Clearon Corporation must “correct deficiencies in their programs and operations” that contributed to the explosion, CSB also calls on the federal agencies to “close a glaring gap in their chemical regulations and provide much-needed additional coverage of reactive chemicals,” according to the board’s press release.

On Dec. 8, 2020, the explosion at Optima Belle’s facility in Belle, West Virginia, fatally injured one worker and caused a fire and chlorine gas release. Optima Belle had been contracted to manufacture chemical compounds on behalf of Clearon. Throughout the day and evening before the incident, Optima Belle employees had attempted to remove water from the compound sodium dichloroisocyanurate dihydrate, also known as NaDCC dihydrate or by the trade name CDB-56, to produce anhydrous sodium dichloroisocyanurate (NaDCC) for use in Clearon’s sanitizing products. CSB warns that, when heated, NaDCC dihydrate may decompose and release toxic chlorine gas and explosive nitrogen trichloride. However, the compound is not covered under OSHA’s process safety management (PSM) standard or EPA’s risk management program (RMP) rule.

The report explains that the machine used to dry the NaDCC dihydrate was paused at 8:13 p.m. while the contents were tested for contamination. The dryer was not properly cooled, allowing its contents to begin to decompose. When personnel resumed the dryer’s operation, its internal temperature increased sharply, as did decomposition of the contents, causing the device to overpressurize and explode, releasing chlorine gas. Dryer fragments struck a methanol pipe, which caught fire.

One Optima Belle board operator was found alive after being trapped by debris. He died later in the hospital of intoxication from the NaDCC fumes he had inhaled. Two other Optima Belle operators were evaluated for respiratory irritation and one local resident reported a leg injury, as the explosion had propelled debris up to half a mile from the facility. Local authorities ordered the nearby community to shelter in place for more than four hours. Optima Belle experienced property damage costing about $33.1 million.

CSB makes 15 recommendations to Optima Belle, Clearon, OSHA, EPA, and other entities in its final report on the incident. Some recommendations address Clearon’s lack of effective process knowledge management systems: the company failed to adequately communicate to Optima Belle information about conditions that could lead to decomposition of NaDCC dihydrate. The parties involved with the operation did not effectively assess the hazards of NaDCC dihydrate, and the dryer was not designed to dehydrate the compound. However, CSB also found that “[h]ad NaDCC dihydrate been covered under the PSM standard or RMP rule, Optima Belle would have been required to implement risk mitigation and management systems that could have prevented this incident,” according to the report.

CSB has urged OSHA and EPA to develop standards for reactive chemicals since at least 2002. “To date, however, neither agency has acted on the recommendations,” CSB states in its press release, which provides additional information and a link to download the report.