Calgary

New gates on Glenmore Dam ready to prevent flooding

New gates on the Glenmore Dam are now ready to use, doubling the capacity to store water in the reservoir and protecting Elbow River communities downstream against smaller floods.

Gates now operational to protect Elbow River communities downstream against smaller events

New gates on the Glenmore Dam effectively double the capacity of the reservoir behind the dam to store water. (Monty Kruger/CBC)

After years of construction, new gates on the Glenmore Dam are now ready to use.

They effectively double the capacity of the reservoir behind the dam to store water.

Many Calgarians are haunted by the 2013 flood which caused billions of dollars in damages in the city.

But the Elbow has seen several smaller-scale flood events since the turn of the century.

A city official said the 21 new gates installed on the dam will now provide protection against a one-in-30-year flood event.

2005 flood levels not an issue now

The leader of watershed analysis for the city's water resources department, Frank Frigo, said this new level of protection would guard against a flood that was seen in 2005 which damaged riverside properties.

However, to prevent damage from a flood like 2013, the gates would have to work in concert with a new off-stream diversion project that the province is planning to build on the Elbow River in Springbank.

A city official said the 21 new gates installed on the dam will now provide protection against a one-in-30-year flood event. (Monty Kruger/CBC)

The new steel gates, which were manufactured in China, replace the previous system of wooden stop logs. Three gates were installed in each of the seven portals across the dam structure.

Each gate is 2.5 metres high, six metres wide and weighs four tonnes.

With electric-powered motorized hoists, the gates can be raised or lowered in minutes.

"They're not unlike a garage door," said Frigo.

"With the 2.5 metres of incremental height they provide, they essentially raise the rim of the bathtub, allowing us more storage to be able to attenuate or slow down high flow of floods that would come in on the Elbow River."

Complicated job done in stages

He said installing the gates has been a complicated feat of engineering.

Starting back in 2017, work was undertaken to remove water and gas utility lines that previously ran across the top of the dam.

A tunnel was bored downstream of the dam and the utilities were relocated there.

Then, Frigo said structural work was done on the dam.

New piers were added, the front of the dam was extended slightly to accommodate the new gates and the bridge deck was replaced. 

The bridge deck is expected to be reopened to the public in summer 2020. (City of Calgary)

The dam continued its normal operations while the work was done.

While the new gates are now available for use as needed, work is still being completed on the rehabilitation project.

Besides increasing flood control capacity, Frigo said the gates allow for greater water storage which will help Calgary get through drought years.

They can also withstand ice better than the old gates, which means more water can be stored year round.

Pathway returning later this summer

Pedestrians and cyclists are likely looking forward to the return of the pathway which was closed in 2017 across the top of the structure.

No date has been set but it is expected to reopen this summer.

"We do have some additional work to do yet in terms of having safety railings and getting the site ready. Some landscaping and other features need to occur before Calgarians can use the path that will be installed across the reservoir," said Frigo.

The new path will feature separated lanes for cyclists and pedestrians. With the utility lines being removed, there will now be views of both the reservoir and the river below the dam. 

Previously, only views of the reservoir to the reservoir could be had while crossing the dam.

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