Hazardous Materials Accident Brief - Chemical reaction during cargo transfer

Whitehall, Michigan
June 4, 1999

NTSB Number: HAR-00-03
Accident No: DCA99MZ006
Adopted June 13, 2000
PDF

The Accident

About 3:30 a.m. on June 4, 1999, a Quality Carriers, Inc., truckdriver arrived at the Whitehall Leather Company1 tannery in Whitehall, Michigan, to deliver a load of sodium hydrosulfide solution. The truckdriver had never been to the plant before. Upon arrival, he asked a tannery employee for assistance. The employee called the shift supervisor, who met the driver at the plant employee's work station.

The shift supervisor stated that the only chemical shipment he had previously received on the third shift was "pickle acid" (ferrous sulfate). He said he had not been told to expect the delivery of another chemical on the shift, so he assumed this load was also pickle acid. The supervisor stated that because the driver did not know the plant's layout and was unfamiliar with where to unload his cargo, he walked the driver through the plant and out to the pickle acid transfer area. The supervisor did not verify what chemical was being delivered. The shipping documents identified the cargo as sodium hydrosulfide solution.

The shift supervisor showed the driver the ferrous sulfate connection (the only working transfer connection at that location) so he could deliver his product. The shift supervisor then unlocked a gate to allow the driver to bring his vehicle onto the plant property. The driver asked the supervisor to sign the shipping documents so he would not have to find the supervisor after the transfer was completed. According to the supervisor, he signed the paperwork without reading it and left the area. The signature block that the supervisor signed stated the following: "I have checked the documents for this shipment and verify that there is adequate storage room to receive this shipment and connection has been made to the proper storage facility."

No plant employees were in the vicinity of the transfer area. When the driver arrived at the transfer area, a transfer hose was already connected to a pipe, marked "FERROUS SULFATE," on the side of the transfer building. During the postaccident investigation, investigators found the other end of the transfer hose connected to the cargo tank and determined that sodium hydrosulfide solution had been transferred from the cargo tank into the storage tank containing ferrous sulfate. (Sodium hydrosulfide solution reacts with ferrous sulfate solution to produce hydrogen sulfide, a poisonous gas.)

About 4 a.m., an employee in the basement of the tannery building smelled a pungent odor and lost consciousness. The employee said that after regaining consciousness about 10 minutes later, he made his way out of the tannery to an area adjacent to the south parking lot, where he found other employees on break. One of these employees called 911.

The driver was found unconscious inside the tannery building approximately 230 feet from the transfer area. He was pronounced dead at the scene and was later determined to have been overcome by hydrogen sulfide gas. No telephone or other means of communication was located near the transfer area that the driver could have used to notify plant personnel of an emergency. Postaccident investigation revealed that both the emergency valve at the rear of the cargo tank and the compressed air valve, located inside the tannery building approximately 40 feet from the transfer area, were closed and secured.

Probable Cause

The National Transportation Safety Board determines that the probable cause of this accident was the failure of Whitehall Leather Company to have adequate unloading procedures, practices, and management controls in place to ensure the safe delivery of chemicals to storage tanks. Contributing to the accident was the failure of the U.S. Department of Transportation to establish, and oversee compliance with, adequate safety requirements for unloading hazardous materials from highway cargo tanks.

Recommendations

As a result of its investigation of the June 4, 1999, accident in Whitehall, Michigan, and the November 19, 1998, accident in Louisville, Kentucky,6 and the the Safety Board issues the following safety recommendations:

To the Research and Special Programs Administration:

Within 1 year of the issuance of this safety recommendation, complete rulemaking on Docket HM-223 "Applicability of the Hazardous Materials Regulations to Loading, Unloading and Storage," to establish, for all modes of transportation, safety requirements for loading and unloading hazardous materials. (I-00-6)

To the Occupational Safety and Health Administration:

Require that facilities where bulk hazardous materials are transferred be equipped with a means of emergency communications. (I-00-7)

To Ford Motor Company:

Distribute written safety-critical procedures for unloading bulk shipments of hazardous materials to all Ford Motor Company employees who are engaged in cargo transfer operations, and conduct initial and recurrent training on the procedures. (I-00-8)

To the American Chemistry Council:

Revise, in cooperation with National Tank Truck Carriers, Inc., the Manual of Operating Recommendations to include specific recommended practices that can be implemented to prevent the unloading of hazardous materials into the wrong storage tank. For example, drivers should personally verify or question all transfer connections before beginning delivery of product. (I-00-9)

Inform your members of the facts and circumstances of the June 4, 1999, accident in Whitehall, Michigan, and the November 19, 1998, accident in Louisville, Kentucky, and emphasize the importance of implementing specific safety-critical hazardous materials cargo transfer procedures and training employees in those procedures. (I-00-10)

To National Tank Truck Carriers, Inc.:

Revise, in cooperation with the American Chemistry Council, the Manual of Operating Recommendations to include specific recommended practices that can be implemented to prevent the unloading of hazardous materials into the wrong storage tank. For example, drivers should personally verify or question all transfer connections before beginning delivery of product. (I-00-11)

Inform your members of the facts and circumstances of the June 4, 1999, accident in Whitehall, Michigan, and the November 19, 1998, accident in Louisville, Kentucky, and emphasize the importance of implementing specific safety-critical hazardous materials cargo transfer procedures and training employees in those procedures. (I-00-12)