Council agrees to explore dam options
A flood of new information by a community group intent on saving two dams at Colliery Dam Park has resulted in city council agreeing to explore options other than removal.
In early November, city council decided in camera to remove the two dams and drain the lakes at the park because of the potential threat to human life posed in the event of an earthquake or extreme rainfall.
That decision drew heavy criticism from the community which views the park as a south end jewel, and resulted in the formation of Save the Colliery Dams representatives, a group of residents who want to see other options explored.
On Monday, members of the group presented city council with options they say they feel the city didn’t adequately consider before deciding to remove the dams and, in their view, ruin the park.
Council responded by agreeing to direct city staff engineers to explore options for dam rehabilitation, repair or replacement, an exercise that will cost as much as $60,000 and take at least six months to complete.
The lakes were scheduled to be drained and the dams removed next summer when water flow is expected to be at its lowest. The deconstruction cost is estimated at $7 million.
Lorne Gale, an engineer with a doctorate in fluid dynamics surface chemistry, and member of Save the Colliery Dams, provided council with alternatives to removal and cost estimates for mitigating the threat in the event of a natural anomaly.
Gale suggested the dams could be rehabilitated enough to reduce the risk at a cost of $500,000 each, with the spillways being upgraded to handle a 1,000-year rain event, enough to reduce the threat of a breach from the Dam Safety Branch’s ‘extreme’ rating to ‘high’.
“The total cost would be about $3 million and it wouldn’t be that difficult a task to do,” said Gale. “The risk can be mitigated at a substantially less cost than to remove them, and we get to retain a jewel in our city. Is that not a reasonable solution?”
Other ideas also came forward, such as generating power at the site, a possibility that could also produce revenue and reduce greenhouse gas emissions.
Coun. Diane Brennan challenged Gale, asking him why council should consider his ideas over city engineers and a $65,000 consultant report.
Bill Sims, the city’s manager for water resources, said city engineers did perform a myriad of tests and considerations and concluded that dam removal to eliminate risk to people and property was the most appropriate decision.
“Overall, why should I prefer your opinion on the cost estimates to the opinions we’ve received [through staff]?” Brennan asked Gale.
“We’re just trying to establish that reasonable consideration was not given to all of the options,” said Gale.
Mayor John Ruttan said he felt the new and conflicting information obligated council to consider alternatives and review options.
City staff, council and members of Save the Colliery Dams Representatives have agreed to exchange information further and meet with provincial Dam Safety Branch officials to determine if options proposed by the group are attainable.