A report released Wednesday by BC Hydro found that the windstorm on Dec. 20, 2018, was the most destructive in the utility’s history.
In the storm report, BC Hydro said the windstorm, which hit British Columbia’s south coast, impacted more customers, caused more damage and required the largest mobilization of resources than any previous storm in its history. BC Hydro was created in 1962 when the provincial government merged the BC Electric Company with the BC Power Commission.
“One of the main reasons the storm was so damaging is that wind came from multiple directions and, when combined with the rain, destabilized, uprooted and damaged trees and vegetation throughout Vancouver Island, the Gulf Islands and parts of the Lower Mainland and Fraser Valley. This resulted in an unprecedented amount of damage to BC Hydro’s distribution infrastructure,” the report said.
The new numbers released by BC Hydro shows more than 750,000 customers were without power on Vancouver Island, the Lower Mainland and the Gulf Islands following the windstorm, larger than the August 2015 windstorm that affected the Lower Mainland and the Fraser Valley.
It was also larger than the windstorm in 2006, which impacted Vancouver Island and levelled thousands of trees in Stanley Park.
According to BC Hydro, during the early morning of Dec. 20, winds came from the southeast. By the late morning, they were coming from the south, and by the early to mid-afternoon, they were coming from the southwest.
Southwest winds are known to cause significant damage across the Cowichan Valley, Duncan, Nanaimo and the Gulf Islands. They happen less frequently than other wind directions. The duration of strong southwest winds in Duncan on Dec. 20 was more than 12 hours, and Salt Spring Island and some of the other Southern Gulf Islands experienced them for eight hours.
“In addition, the low-pressure centre of the storm tracked across north-central Vancouver Island, making it the optimal storm track for strong winds over the most populated areas of the south coast—the southern half of Vancouver Island and the Lower Mainland,” the report said.
“The storm’s central pressure was 982 millibars, which made it much more intense than most storms that typically cross the south coast. For reference, a Category 1 hurricane has a central pressure of about 980 millibars.”
Wind speeds during the storm were generally between 70 to 100 kilometres per hour, but in some areas, the wind gusts went over 100 kilometres an hour.
During the storm, the wind toppled trees and branches, with many ending up on electrical equipment.
The windstorm on Dec. 20 was proceeded by heavy rain. BC Hydro said more than 400 millimetres of rain fell in some areas over the week leading up to the storm, destabilizing trees.
“As a result, soils were completely saturated to a point where they were seeping water even when it was not raining. Saturation reduces the stability of the soil and some coniferous trees, like Douglas firs and hemlocks, have shallow roots making them more vulnerable,” the report said.
BC Hydro states in the report that the windstorm was the first on the south coast since last winter and the “clearing” effect that would have occurred through several smaller windstorms had not happened. Therefore, there was a higher amount of vegetation susceptible.
Nearly 350,000 BC Hydro customers, or more than 80 per cent of all customers, on Vancouver Island and the Gulf Islands, were without power following the storm. There were more than 400,000 customers in the Lower Mainland also in the dark.
More than 1,900 spans of wire, 390 power poles, 700 cross-arms and 230 transformers had to be repaired or replaced and more than 900 hydro crew members were out in the field, including crews from the B.C. Interior and contractor crews from Alberta and the east coast.
“Responding to this storm involved our biggest mobilization of crews, equipment and materials ever,” Chris O’Riley, BC Hydro’s president and chief operating officer, said in a statement.
There were more than 5,800 trouble orders, which is how work is assigned to crews so that power can be restored. It ranges from removing a tree from a line to replacing a power pole. The number of trouble orders during December’s storm was 19 times greater than BC Hydro receives during an average storm.
Within the first 24 hours after the storm, BC Hydro had restored power to more than 550,000 customers. All customers in the Lower Mainland and Vancouver Island had power by Dec. 24. However, due to the extent of the damage on Vancouver Island and the Gulf Islands, and difficulties accessing areas due to trees down on the roads, it took longer to restore power to those areas.
On some of the Southern Gulf Islands, the Ministry of Transportation and Infrastructure recorded trees down on 100 per cent of the roads.
“While BC Hydro made significant progress restoring power to customers in the first few days, it was not able to move its crews around as easily as it would during a typical windstorm because it hit four regions at once,” the report said.
“Typically, BC Hydro is able to move crews quickly between the regions so that it can get extra help to the hardest hit areas. Moving this many crews and bringing the trucks, heavy machinery and materials that were needed to rebuild the system over to the many islands and regions added an additional layer of complexity. This was one of the reasons there were longer than average restoration times for many customers.”
In some areas, portions of the distribution system needed to be completely rebuilt due to the destruction. On Salt Spring Island, more than 500 spans of wire needed to be replaced and crews were brought in by water taxi. Some of the materials and equipment were sent over by barge.
And in some rural areas in the south coast, crews used ATVs or hiked to sites to restore power.
All customers impacted by the storm had power restored by mid-day Dec. 31.
BC Hydro said over the past two decades, three major storms have impacted the south coast. In 2006, 240,000 customers lost power after a storm in early December. It caused destroyed a section of Stanley Park and impacted many on Vancouver Island.
“At the time, it was considered the single largest storm impact in BC Hydro’s history, and it did more damage to the distribution system than what would typically be experienced in an entire year,” the report said.
The next major storm was in August 2015 when the Lower Mainland and Vancouver Island were hit by a late summer windstorm. Approximately 700,000 customers lost power and at the time, it was the highest number of outages following a storm in BC Hydro’s history.
The windstorm on Dec. 20 was more damaging than the 2005 and 2015 windstorms, BC Hydro said. More than 750,000 customers lost power, which is more than 60 per cent of customers impacted by storms in all of 2017.
While the number of power outages was not much higher than the August 2015 windstorm, there was more damage in December, There was a total of 10,000 metres of damaged power lines in 2015 compared to more than 86,000 metres during last months storm.
BC Hydro said there is room for improvement for future storms.
During the December 2018 storm, some customers had problems reporting downed lines because 911 operators in some areas were flooded with calls.
Others were frustrated that they could not find an outage status for their area. In the report, BC Hydro said it is looking at ways to support communities affected by outages more than 72 hours longs, including having customer service representatives available for face-to-face communication.
BC Hydro said it can also work with cities and municipalities to better map out major intersections and primary traffic routes to prioritize circuits feeding those areas. The utility said this will prevent major traffic congestion and safety risks.
“Reflecting on how we can improve is an important part of how we debrief after every storm. We will continue to work on improving how we respond to storms so we will be ready for the next event Mother Nature throws at us,” O’Riley said in a statement.
BC Hydro said it will be tallying the cost of the storm in the next few weeks.
“BC Hydro released a report in November 2018 that found storms and extreme weather events in B.C. are becoming more frequent and severe. In the past five years, the number of individual storm events BC Hydro has responded to has tripled. The December windstorm is another indicator that this trend is not slowing down, and the frequency and severity of the storms are
now increasing. For example, this storm generated more than twice the number of storm-related outages than BC Hydro experienced in all of 2013,” the report said.