A manufacturer’s defect was to blame for the collapse of a concrete pumper truck that killed one man and seriously injured another at a Chilliwack construction site a year ago.
That’s the conclusion of a WorkSafeBC report obtained by The Progress through a freedom of information request.
It was March 11, 2016 when the KC’s Pumping Services truck was in position at the 53-unit townhouse project in Garrison Crossing with the concrete placing boom fully extended. At approximately 7:40 a.m., the front right outrigger of the truck failed, and the boom came down, striking two workers – a concrete placer and a crew foreman.
The concrete placer, 24-year-old Sebastian Gomez Obando, was killed, and the foreman suffered life-altering injuries.
Obando was born in Colombia, and was survived by a wife and two children. A GoFundMe campaign was quickly launched to help the family, which to date raised almost $25,000.
WorkSafeBC began an investigation into the incident as soon as it happened. The final report was issued March 16, 2017.
As part of the investigation by WorkSafeBC, a metallurgical analysis was done on the collar plate that fractured causing the 2008 concrete pumper truck to tip over. The analysis found the piece of metal was a low-alloy, medium-carbon steel plate containing manganese, chromium, and molybdenum, but no nickel.
“Therefore, it did not meet any North American grade of steel,” lead investigator Gary Anderson wrote in the report.
Further analysis determined the steel parts came from a manufacturer in South Korea.
“Analysis shows that the steel of the fractured collar plate is very brittle,” he wrote, adding that the piece that broke, showed “very brittle behaviour,” unlike other similar parts on the truck.
The low fracture toughness was determined to most likely be caused from improper heat treatment by the steel manufacturer. Several welding defects were also found in the collar plate.
The report concluded that a four-millimetre-deep crack had developed within 48 hours after the welding process.
“This initial crack, in combination with the extremely low level of fracture toughness of the collar plate, resulted in the collar plate’s failure at the time of the incident.”
The number of employees on site at the time and the years of experience of the placer, the foreman and the pump operator was information blacked out in the incident investigation report obtained by The Progress.
The report did note that no workers had anything to do with the accident.
In the “health and safety actions” section of the report, WorkSafeBC published a bulletin with a reminder to the concrete pumping industry to:
“Follow manufacturer’s instructions for operating and maintaining outriggers and booms on concrete pumper trucks;
“Regularly inspect all welds and stress points on outriggers and booms;
“Position outriggers according to manufacturer’s instructions and based on soil stability.”
There is no blame attributed in the report and no further enforcement of any rules or laws recommended.
