City staff say sewage system can handle infill

By Phil Tank, The StarPhoenix December 12, 2013 - City of Saskatoon staff are preparing to handle any increase in sewage and water volume that will accompany infill development. Concerns were expressed at Tuesday's planning and operations committee that adding infill developments and population to older neighbourhoods - by permitting garden and garage suites and outlining rules for new single-family homes - will place too great a strain on the older infrastructure in those areas, specifically water and sewage systems.

Galen Heinrichs, the city's water and sewer engineering manager, said increased capacity is not an issue with older infrastructure such as water or sewer pipes.

"It's aging because of time," Heinrichs said Wednesday. "It really has nothing to do with whether you're adding or taking away more flow."

Heinrichs said there are no capacity concerns with the volume expected from adding infill at the neighbourhood level, but the pipes that connect to several neighbourhoods - called trunks - present a different problem.

"What may be a concern is, suppose you have several neighbourhoods that are putting a few more suites in," Heinrichs said.

Starting next year, a new pipe will divert household sewage from the sanitary sewer interceptor, which runs from the north side of Idylwyld Bridge all the way up to the sewage treatment plant in Silverwood Heights on the north/west side of the South Saskatchewan River.

The interceptor, a concrete pipe 1.8 metres in diameter, was built in 1912 and runs about three metres under the ground along the riverbank, using gravity to move the sewage along next to the river, which slopes downward as it winds its way through the city.

Right now, sewage from the west side of the city runs through the interceptor, but starting in 2014, the Blairmore force main polyethylene or plastic sewage pipeline will use pressure to transport sewage from the west side of the city through the north end by the airport to the sewage plant.

Heinrichs said this diversion will free up the capacity of the interceptor to accommodate thousands of people, reducing any concern about capacity with infill.

"It is a legitimate concern and that's why we've done what we've done," Heinrichs said.

Alan Wallace, the city's manager of planning and development, said city administration is not "overly concerned" about straining infrastructure by adding infill dwellings like garden and garage suites.

"We're confident that we have infrastructure to support neighbourhood level infill," Wallace said.

Every application for infill development will be considered on its own merits and engineers will be consulted on matters of infrastructure, he said.

"If you can't get water and sewage to a dwelling, you can't have a dwelling."

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