“Gaps” in BC Hydro’s work procedures, including an outdated system and incompatible materials, were contributing factors in an underground electrical vault fire and explosion that injured two in Vancouver earlier this year, an independent report has found.
A BC Hydro assessment in 2016 had further identified catastrophic safety risks associated with the vault, recommending its replacement in 2018 — an in-house warning the utility provider did not follow.
The Feb. 24 explosion outside the iconic Marine Building on Burrard Street left two people with lacerations and facial burns, as windows in the building blew out and firefighters battled what was described at the time as a “fireball” stretching four storeys high. The explosion shifted concrete in the downtown area, shut down a portion of the road for weeks and resulted in costly repair work.
An investigation into the incident by Senez Consulting Ltd., published Thursday, found a buildup of combustible gases was to blame — the result of partial discharges of electrical energy into the vault’s insulating oil. That oil had deteriorated over time and lost its insulating property.
“The contamination occurred due to a leaking gasket in the lid of the switch. This was caused by incompatible products and potential contamination of the seal, compromising the nitrogen pressurization, and etching the surface of the enamelled paint inside the switch,” the report said.
Corrosion then occurred in the steel below the surface of the paint, creating a dangerous mix of iron and oil, the discharges of electrical energy, and the accumulation of gases that eventually ignited, bursting through the sidewalk in a fiery explosion.
According to the report, BC Hydro had “limited guidance” on required visual inspections with “no defined replacement parts” and “no end-of-life timing for the gaskets” of the vault.
“This left field crews to find gasket repair solutions that were insufficient and involved incompatible materials,” Senez Consulting wrote.
The company also found BC Hydro’s oil-testing program was not up to snuff — not having been updated to reflect changes in standards and limited in its controls and tracking.
“A more thorough program may have identified gasket sealing issues had the details of the pressurized tanks been tracked, but a specific
correlation to this incident was not identified,” the report found.
The investigation further uncovered that serious risks had previously been identified regarding BC Hydro’s underground street vaults. BC Hydro’s own assessment in 2016 found that 14 such vaults — including the one on Burrard Street — would pose a “high risk” in the event of a failure.
According to BC Hydro, that assessment warned that if the vaults weren’t properly maintained or replaced, the result could be severe injury or death. It recommended replacing the Burrard Street vault in particular by 2018.
The vault, however, was removed from a subsequent system improvement project so that a nearby vault in Gastown could be upgraded instead. BC Hydro intended to do maintenance work on the Burrard Street vault, but that never happened, CEO Chris O’Riley said Thursday.
“Our crews had difficulties performing the maintenance, despite their best efforts, because they did not have the proper information and instructions or the correct materials to complete the maintenance work,” he told reporters.
“We should have caught this much earlier and we didn’t.”
In response to the investigation, the provincial Crown corporation has vowed immediate action, including a program review of other distribution street vault equipment, with third-party involvement. That review is expected to be completed by March next year and BC Hydro said it will share its findings with other utilities.
“In my more than 30-year career at BC Hydro and in my time as president and CEO, I have never been as disappointed as I am today to share this news,” O’Riley said, apologizing to all those hurt in the explosion.
“Following the investigation I take responsibility on behalf of BC Hydro for the failures that occurred and this incident should never have happened.”
The provincial Crown corporation has already decommissioned what it said were the only two similar electrical vaults in the province, out of an “abundance of caution.” One was on Gilford Street near Henshaw Lane in Vancouver’s West End and provided power to about 350 people, while the other — on Keefer Street between Gore and Jackson avenues — served about 250 people in Chinatown.
On Thursday, it further said it has decommissioned all 14 underground vaults with oil-filled equipment that were identified as risks in the 2016 assessment..
In the aftermath of the explosion, BC Hydro insisted the incident was a rare occurrence and its equipment is regularly inspected and maintained.
The utility provider also said it has reached out to businesses damaged by the explosion and remains committed to cooperating throughout their insurance claims processes. JJ Bean and Tractor Foods in the Marine Building have been closed for repairs since the incident.