Hydrovac boom arm came into contact with overhead electrical lines
PGC Services and K-Line Maintenance & Construction have been fined a total of $285,000 after a worker was killed when a boom became activated and came into contact with live overhead electrical lines. The incident occurred on Nov. 24, 2015 at a K-Line construction project located along the north side of Highway 7 in Thornhill, Ont.
Following guilty pleas, K-Line was fined $160,000 and PGC was fined $125,000. The court also imposed a 25 per cent victim fine surcharge as required by the Provincial Offences Act. The surcharge is credited to a special provincial government fund to assist victims of crime. The conviction took place Feb. 15, 2018.
K-Line was retained by the utility owner to replace the existing overhead lines. PGC was sub-contracted to excavate holes for the installation of new electrical utility poles.
Hydrovac excavation was being used on the site. Crews use specialized hydrovac trucks equipped with long articulating booms along with a high-pressure water hose and a water tank. On November 24, 2015, PGC sent two of its hydrovac crews to the site. The two crews then began setting up their equipment by extending the boom arms of the hydrovac trucks and by installing dig tube extensions to allow the vacuum to reach the excavation areas.
The excavation area along the road was serviced by existing overhead power lines with a phase-to-phase voltage of 27,600 volts and the work was taking place in proximity to the lines.
All members of both crews were busy performing work tasks preparing the equipment for excavation. There was no one present monitoring the movement of the hydrovac boom arms in order to warn the operator to ensure the equipment did not encroach upon the legal safety standard, which states: "No object shall be brought closer than 3 meters from an energized overhead electrical conductor with a nominal phase-to-phase voltage of between 750 and 150,000 volts."
The boom arms of the hydrovac trucks are operated by a remote control. For the truck operated by the first crew, movements were controlled by a series of elevated toggles on the unit. One of the workers was removing the final dig tube from its storage rack on the driver's side undercarriage of the first truck. This worker, while attempting to pull the dig tube out of the rack, had the boom's remote control unit hanging underneath one arm.
The other worker, on the passenger side of that truck, had pulled a length of the high pressure water hose from its spool in the equipment cabinet on the undercarriage of the truck, and was in the process of attaching it to the digging gun/water wand used for the excavation. The water hose was connected to the truck, and has a metal-mesh lining that is a conductor of electricity.
As the driver's-side worker was pulling the final dig tube out of the storage rack, one or more of the toggles on the remote control was triggered by coming into contact with or being caught on a body part or a piece of clothing. The movement of the toggle(s) caused the boom arm to move and to come into contact with the overhead electrical lines parallel to the road.
The boom arm's contact with the 27,600-volt energized overhead electrical conductor caused the electrical current to pass through the first truck. The worker on the passenger side of the truck was fatally electrocuted.
The boom arm was on fire in the overhead electrical lines. The remote control was used to separate the boom arm from the lines. Emergency services were called. The worker was pronounced deceased at hospital.
PGC failed as an employer to ensure that no object was brought closer than 3 meters from an energized overhead electrical conductor, as required by section 188(2) of the Construction Regulation, violating section 25(1)(c) of the Occupational Health and Safety Act (OHSA).
K-Line failed as a constructor to ensure that a designated signaller was in place to warn the operator each time any part of the vehicle or equipment approached three meters from an energized overhead electrical conductor as required by section 188(8) of the Construction Regulation, violating section 23(1)(a) of the OHSA. This section of the regulation requires a constructor to ensure that a competent worker is designated as a signaller and stationed so that he or she is in full view of the operator and has a clear view of the electrical conductor and of the vehicle or equipment, and that the signaller warn the operator when any part of a vehicle or equipment approaches the minimum distance from an energized overhead electrical conductor. A signaller shall not perform any other work while acting as a signaller.
Source: Ontario Ministry of Labour