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Core samples drilled from Nanaimo's Colliery dams
The bill for the Colliery dams continues to mount as the city’s technical committee hunts for a solution to remediate the century-old structures.
Golder Associates has been drilling core samples from the lower Colliery dam this week to test the state of the structure.
According to the city’s technical committee, the work is needed to fill information gaps on the condition of the dams and will help narrow down potential long-term options for repair.
But the work also delays answers about the future costs of the dams by another month, and will come at an “additional cost” to the city, according to Mayor John Ruttan, who says the overall bill for the dams is now close to $1 million.
City staff members did not have the exact cost of the core-drilling work nor were they able to provide a budget for the technical committee, but said work will still be within the $100,000 to $400,000 range estimated for this phase of a two-year risk mitigation strategy.
“The engineers say we need this information. We don’t want them to do it. We don’t want to spend on information, but they say without drilling they are not able to give us a precise estimate on what it will cost to do the work,” said Ruttan, who has expressed concern about escalating costs.
The city’s technical committee spokeswoman Katherine Gordon says the core samples are very important work in moving forward remediation plans and will give the technical committee and its engineers a more complete picture of what has to be done.
“If you liken it to repairing a tooth – a dentist isn’t going to stick a crown on the tooth without looking at what’s inside,” she said. “The engineers need to know exactly what the condition of the dams are in order to be able to suggest a technical solution that is going to meet the required safety standards.”
The core drilling work which ends Friday will be testing the foundation of the lower Colliery dam and the embankment to see what it’s made of and what the condition is. A report is expected to be released by the technical committee in March – the same time the city anticipates it will present its own budget information for the Colliery dams.
The work on the dams started in October after Nanaimo city council unanimously agreed to launch a two-year process to mitigate risk posed by the middle and lower Colliery dams in an earthquake or flood. The multi-phased process is focused on remediation of the dams, an option council had originally dismissed because of a $17 million to $30.7 million price tag. The first phase of work began in December. Construction on long-term mitigation measures is slated for 2015.