Lower Colliery Dam lake shown above.

Lower Colliery Dam lake shown above.

City of Nanaimo’s Colliery dam spending tops $7 million

NANAIMO – City staff begin study of middle dam structure this fall.

  • Sep. 28, 2016 8:00 a.m.

More than $7 million has been channelled into Nanaimo’s Colliery dam in the past four years, according to the City of Nanaimo, which is now tackling the middle structure.

The City of Nanaimo released an update on expenses for the lower Colliery dam auxiliary spillway, completed this year, as well as total costs for the dams since 2012, including evacuation planning, legal fees, and the Colliery Dam Select Committee. There was no break-down of the costs provided.

Expenses for the dams are now $7.07 million, and the cost for the auxiliary spillway is now expected to be $4.46 million – close to a $4.5-million estimate provided earlier this year.

A city report says with construction complete and minimal future costs expected, the final cost can now be predicted more accurately. Work is still ongoing, but is included in the most recent tally.

Mayor Bill McKay says the total for the dams is less than originally anticipated, which was between $10 million and $15 million.

“We have to remember that Nanaimo is unique … there’s only one other community in Canada that I know has made a significant investment to remediate recreational dams and that’s Moose Jaw. The fact is, a decision was made by the governors of the City of Nanaimo to remediate, the cost is less than what we originally anticipate and we move forward,” McKay said. “Hopefully we are going to continue to put some more effort into the Colliery dam park to make it a better place for people to go.”

The city has been under order by the province to address potential safety hazards at the lower and middle Colliery dams.

In February, the city estimated the remediation work at the lower dam would cost $4.5 million, the high end of an earlier estimate and more than $300,000 over budget. The project has run into ongoing engineering supervision and environmental monitoring, as well as issues such as over-excavation and the need for a temporary bridge. City officials previously said the typical construction process wasn’t done because of tight timelines, outlined by the province in its order to the city.

The city is still mandated by the province to address the middle dam and there’s $75,000 in this year’s budget to assess the structure.

Poul Rosen, senior manager of engineering, said the city intends to proceed with a dam safety risk assessment this fall which will look at seismic and high-flow risk, probabilities of that area and consequences.

“The other important piece is that we’re intending to undertake some data collection on the dam system as well, so things like flow monitoring and making sure we’ve got adequate rainfall gauges and so on within the catchment,” he said. “In the future, if we need it we have an opportunity to have a very high quality hydraulic model and hydrology model.”