Saskatoon undertakes major expansion of water reservoir system

Seeking to increase water storage capacity during peak summer months, the City of Saskatoon has started work on a major expansion of its water reservoir system that will take two years to complete.

Of the city’s three water reservoirs, two will be expanded to meet future demand and will undergo a number of modifications and improvements.

The city’s 19 million-litre-capacity Avenue H reservoir on the southern bank of the South Saskatchewan River will be doubled in size to hold a total of 38.5 million litres.

The storage capacity at the 42nd Street reservoir, which at present holds close to 36 million litres, will be boosted by 20 million litres of water.

Associated Engineering in partnership with the Calgary office of CH2M Hill designed the expansion plans.

There has been an active water treatment facility at Avenue H for more than 100 years.

“(The work will) assist in the high demand periods for water usage, to stabilize the production at the water treatment plant to work on average demand rather than maximum demand requirements,” said Krystyna Kotowski, Saskatoon’s senior project management engineer.

“We would rather reach the required equalization storage capacity needed to meet peak hour demand in excess of production capabilities and work off that.”

More storage capacity will allow the water treatment plant to cut the volume of water it pumps out through the day, which strains the plant’s infrastructure.

“We don’t ration, we just have to push the equipment a lot harder. We’ve never compromised quality of water, but we’d always like to have some room,” she said.

Kotowski added that three to four per cent of all the treated water produced is pumped back into the system for filter cleaning, so additional water is always needed for that, too.

“The frequency of the filter cleaning is dictated by the turbidity of the water,” she said.

“Turbidity is highest in spring, so the filter needs to be cleaned more, once every 12 hours, but it does depend on season.”

In addition to expanding the Avenue H reservoir, Saskatoon will also build two new facilities that will be located next to the existing reservoir— an ultraviolet (UV) disinfection facility and a high lift pump station.

Water will be pumped past a series of UV lamps to neutralize organisms missed by chlorination.

“The system will comply with anticipated future regulations,” Kotowski said. “We’re expecting it to be added so we are adding this additional barrier to our process, which includes chlorination.”

Graham Construction was awarded the contract in March 2012 following a seven-firm competition.

They will perform all of the concrete work and all contracting duties on the project, and will build a skywalk connecting the old building to the new one.

While the existing 19 million-litre round reservoir structure will remain unchanged, a new reservoir will be built about five metres below ground in a tank across the street from the older facility, said Graham project engineer Mark Patola.

“The four-storey tall UV disinfection and high lift pumping station building will then be constructed on top of the new reservoir,” he explained.

The total cost for the entire Avenue H reservoir expansion and the UV disinfection facility project is currently estimated at $35 million.

“This is a pretty fair size contract for Graham and one of the biggest Saskatoon has ever awarded,” he said.

The Avenue H project is in its initial shoring phase.

Patola said that working around some of the old underground utilities is a bit of a challenge, but nothing they can’t handle.

“Some of the underground utilities under there are pretty old, such as sanitary and watermains,” he said.

“But, in terms of supporting them and working around them, we’ll cross that bridge when we get there.”

Following the shoring work, Graham will dig the tanks and then get to work on the concrete, mechanical and electrical work.

“We have a lot of sub-trades on the job, making up a significant amount of the contract value,” he said.

“Mechanical and electrical are a couple of the large ones.”

The 42nd Street reservoir expansion project will include the construction of a new pumping house. The estimated cost is about $22 million.

The government of Canada and Saskatchewan are contributing through Infrastructure Canada’s Canada-Saskatchewan Building Canada Fund-Major Infrastructure Component.