Unattended Tank Led To Explosion

Overheating of an unattended mixing tank holding heptane and propyl alcohol led to a massive explosion and fire at a Danvers, Mass., paint and ink manufacturer in November 2006, says the Chemical Safety & Hazard Investigation Board (CSB) in a report released on May 13 at a public meeting in Danvers. The board also announced it had reached an agreement to ensure unfettered access to Massachusetts chemical accident sites and is pushing for similar authority elsewhere.

The CAI/Arnel plant accident occurred during early morning hours long after workers had left. Scores of homes were destroyed and some 300 residents were evacuated.

"The community damage was the worst in CSB's 10-year history," board member William Wright says. However, the accident caused only minor injuries, mostly because of its timing.

CSB's report recommends tougher state and local inspections and oversight, which would have discovered that the plant lacked automatic process controls and alarms. The board also released a 10-minute accident video (www.csb.gov).

Initially, state and local fire investigators blocked board investigators from the site for a week. When CSB finally accessed the site, its investigators found that the area had been disturbed and evidence had been removed. CSB has complained of similar problems during other investigations.

"We made great progress with Massachusetts authorities in the past few months," CSB Chairman John Bresland tells C&EN. "State and local officials support our findings and recommendations, including our call for improved state and local oversight of hazardous chemical facilities. Last week, we received assurances from the state that at future incident sites, CSB's investigations can proceed concurrently with the state's criminal and civil investigations."

The situation CSB encountered at Danvers is a national problem and highlights ambiguities in CSB's authorizing statute regarding site access and evidence preservation, Bresland says.

"Over the next several months, I hope to work with our congressional authorizing committees to resolve these ambiguities," Bresland says. "The National Transportation Safety Board, for example, has much clearer authorities in its statute."

In a report to Congress last year, CSB laid out incidents in which state, local, federal, and chemical company officials hindered board investigations.

That report identified CSB's probe of a 1999 fire at the Tosco refinery in Martinez, Calif., which killed four workers. Company officials blocked CSB by refusing to allow employees to be interviewed. Another example given was the investigation of a lethal explosion at a Motiva refinery in Delaware City, Del., in 2001; Motiva hampered CSB when it withheld materials and witnesses. And in the investigation of an explosion at the First Chemical facility in Pascagoula, Miss., in 2002, company officials refused to allow CSB's team to enter the site.

During some 18 investigations, CSB staff was restricted in gathering evidence. Even during the board's biggest investigation, that of the 2005 explosion at BP's Texas City, Texas, refinery, BP challenged CSB's authority, according to the report.