Canmore Town council has added a new capital project for this year that will permanently remediate a nearly five metre deep sinkhole in Three Sisters Mountain Village.
Late last year, Mayor John Borrowman announced the Town had received a $600,000 grant from the Province to fix the hole, located along a municipal pathway near Dyrgas Gate that formed in May 2010.
At its regular meeting on Tuesday (May 21), members of council voted unanimously to proceed with a capital project to fix the sinkhole, which was the result of an airshaft from Seam No. 4 in the No. 4 mine. The mine was closed in the 1940s.
In a presentation to council, Town manager of engineering services Andy Esarte indicated a significant amount of discussion had taken place regarding liability for potential sinkholes created from developing on undermined lands.
Administration had originally asked council for up to $500,000 to remediate the hole, but upon receiving legal advice, the decision was put aside until it was determined who was actually responsible for the costs.
In announcing the grant last year, Minister of Municipal Affairs Doug Griffiths said the Province would continue to work with the Town in addressing the situation.
“We went through our budget and scraped the corners out and created $600,000 to cover these costs,” Griffiths explained. “There’s nothing more important that we do in the province of Alberta than partner with communities to build stronger communities going forward.”
According to the report provided by Esarte to councillors, following discovery of the large sinkhole, which is also measured at 7.5 metres in diameter, the Town requested the Province pay for remediation as per an indemnity agreement.
However, a letter from municipal affairs said the Province was regulated to claims by third parties only and since no third party was involved in the loss associated with the sinkhole, the Town was left to fix a hole with an estimated cost of between $250,000 and $900,000, according to a consultant.
The $600,000 grant from the Province will provide adequate funds to complete the remediation, but a long-term solution to determine who is liable for situations like this on undermined lands is still being addressed.
“Future development approvals on undermined areas within the Three Sisters lands will create substantial liability and risk for the Town if indemnity is limited only to third party claims against the Town and does not cover direct municipal losses,” the report stated.
“Administration will continue to address the longer term issues with the Province.”
For the remediation itself, the manager of engineering services said geotechnical studies will be conducted within the next six to eight weeks that will allow contractors to propose proprietary or specialized approaches to remediate the sinkhole.
“This is very unique,” he added. “We really need to understand the dimensions and what it looks like underground.”
While no firm date was given, construction is expected to start in fall once geotechnical investigations are complete, which will require approximately $75,000 in funding.
The report also noted that the entire cost of the project would be wholly funded by the provincial grant provided by municipal affairs. If costs are projected to be higher than expected administration will return to council for direction.
