Undergound utilities upgrade work in downtown Nanaimo has stopped after the construction project found itself on unfirm footing.
The work, being carried out in preparation for the downtown renewal project, involved trenching to replace old water mains on Commercial Street, but was halted when test drilling discovered a mine void under the Bastion and Commercial streets intersection in late September and it was feared that trenching to lay new pipes could pose a risk to workers.
Downtown merchants, such as Leon Drzewiecki, owner of NYLA Fresh Thread, say they’ve already suffered impacts to their businesses from street closures due to construction work and TV filming and are still trying to recover from the effects of the COVID-19 pandemic. They're frustrated at the notion of any delay in the current project, he said, adding the city should have known about the mine void before starting construction and closing sections of Commercial Street.
“They started getting everything done, opening up the streets, getting it happening and then after two weeks of them doing that they brought down the drilling equipment,” Drzewiecki said. “The drilling equipment now has found voids under the street, mine shafts under the street. Now everything’s on full stop … so we’re waiting for the engineer’s report to come back to see how they’re going to proceed and they can’t even put a shovel in the ground now until the engineers come back. The best-case scenario is it’s going to be weeks. Most likely it looks like it’s going to be months, so now their end date of next May is going to be blown out of the water.”
Drzewiecki said a lot of businesses downtown can’t weather 10 months of poor sales.
“Unfortunately, NYLA Fresh Thread has been down here for 10 years and this might be our last Christmas,” he said.
Bill Sims, Nanaimo’s general manager of engineering and public works, said in an e-mail the city has long been aware of the mine under the street and geotechnical drilling was conducted in 2023 before work started.
“We knew the mine was there … which is why we did exploratory drilling in 2023, and made a provision for further exploration in 2024,” Sims said. “The original mine would have been deep enough to not create too much concern, but in many cases of coal mines, the roof starts to erode and fall into the mine.”
Sims explained this process is called 'stoping' and migrates upward and often eventually appears at the surface. The void created is not necessarily a cavernous hole underground.
“We believe that’s what we’re witnessing here,” Sims said. “It’s not a massive void – more of an air pocket – but because of the looseness of the soil, it poses a risk if we dig a trench down closer to it.”
These voids were not caused by construction activities, but have been there since the Douglas Seam was worked from 1854-1938. In many cases voids of this nature are only discovered when they appear at the surface in the form of a depression.
Sims said work is continuing away from the air pocket to try to prevent delays in the project schedule.
“At this stage we have enough room in the schedule to avoid major impact,” Sims said. “However, depending on the extents of remediation required, it may create delay. To mitigate this, we are pivoting the work to other areas to ensure that the project continues to progress.”
Sims said the main priority is to ensure workers aren’t at risk, so work will resume south of Bastion Street and then move north of the intersection until the voids are filled with grout. The project’s geotechnical engineering team is working on a grouting program to address the risk of the voids.
“It’s too early to say how long it will take to resolve, but the priority is to get this fixed ASAP, and also mitigating the schedule challenge by relocating works to other areas,” Sims said.
