The review indicated human error is the leading primary cause of incidents during loading and unloading operations.

Agency Wants More Hazmat Tank Truck Risk Assessments

The Pipeline and Hazardous Materials Safety Administration proposed that every carrier or facility involved in loading or unloading a cargo tank motor vehicle perform a risk assessment and also receive training.

The Pipeline and Hazardous Materials Safety Administration is moving forward with a proposed rule that will require every carrier or facility involved in loading or unloading a cargo tank motor vehicle (CMTV) to perform a risk assessment of those operations and implement safe operating procedures based upon it. They would have to receive training and be evaluated on their qualifications to perform loading or unloading tasks, according to the proposed rule published March 11.

PHMSA asked for comments about it by May 10 (, docket number PHMSA-2007-28119).

The proposed rule is intended to reduce hazmat spills and incidents caused by human error and equipment failure. It fulfills recommendations from both the National Transportation Safety Board and the U.S. Chemical Safety and Hazard Investigation Board; it also is based on PHMSA's review of hazardous material incidents. The agency estimates the rule will produce benefits of $18.3 million over a 20-year period.

The review indicated human error is the leading primary cause of incidents during loading and unloading operations -- it accounts for 33 percent of serious incidents where a failure cause was reported and 26 percent of all incident reports reviewed. "During our review of incident data we noted that human error generally was a result of inattention to detail when performing a loading or unloading function; examples include failure to attend or monitor the operation, leaving valves in the wrong position, or improperly connecting hoses and other equipment," the agency notes in its NPRM. "Overfilling of packagings or receiving tanks accounted for 25% of the incidents. Defective or deteriorating devices or components (e.g., valve failure, gasket leak) as the primary cause accounted for approximately 16% of serious incidents, and a variety of other causes (e.g., freezing temperatures, lading plugs in piping, lading/vessel incompatibility) accounted for the remainder. Further, a comparison of the serious incidents shows that the overwhelming majority involved CTMVs by highway; approximately 90% (615 of 680) of the serious incidents occurred during highway loading or unloading operations, and approximately 75% of those incidents involved CTMVs."

Incidents described in the NPRM include:

  • A July 14, 2001, release of methyl mercaptan in Riverview, Mich., from a rail tank car during unloading when a pipe attached to a fitting on the unloading line broke and separated. The methyl mercaptan ignited and cargo transfer hoses on an adjacent tank car were damaged, which released chlorine. Three plant employees died and about 2,000 people living nearby were evacuated.
  • An explosion and release of about 6,500 gallons of hazardous waste from a CMTV on Sept. 13, 2002, at a transfer station in Freeport, Texas. Twenty-eight people received minor injuries, and residents living within a mile of the site had to shelter in place for about six hours.
  • An Aug. 14, 2002, release of 24 tons of chlorine from a rail tank car being unloaded in Festus, Mo., when an unloading hose ruptured. Three residents were admitted to the hospital, and hundreds of residents were evacuated or asked to shelter in place.
  • Another chlorine leak from a hose rupture on Aug. 11, 2005, in Baton Rouge, La., but this time -- unlike the Festus incident -- the emergency shutdown system operated properly, and the release ended in under a minute.

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