EDMONTON – Construction of an underground sewer tunnel that will help improve the water quality in the North Saskatchewan River is finished. However, it’s not completely functional just yet.
Construction on the West Edmonton W12 Sanitary Sewer Tunnel began in 2006. The tunnel will decrease the amount of combined sewer overflow- which is a combination of raw sewage and storm water- that empties into the North Saskatchewan River “to protect the environment,” said Junhao Zou, a senior engineer with the City of Edmonton.
“It will reduce the combined sewer overflow from 200 million cubic metres every year to less than 600,000 cubic metres per year,” Zou explained.
The underground sewage and storm systems combine in older areas, like downtown. According to the city there was less concern about the impact of overflows on the environment prior to the 1950s and it was less expensive to build one set of sewer pipes instead of two.
The City of Edmonton has 18 combined sewer outflow sites which release in to the North Saskatchewan when runoff overloads the system.
“Precipitation is the biggest factor when it comes to river levels in Alberta. We will issue a high stream and flow advisory, or river flood watch, or flood warning when necessary,” said Jessica Potter from Alberta Environment and Sustainable Resource Development.
The West W12 project will divert combined sewage from the Rat Creek outflow- east of Dawson Park- to the Gold Bar Wastewater Treatment Plant, where a real-time control facility for the sewer tunnel is being built. It is scheduled to be fully operational by the end of November.
“Even before the operation of the real-time control facility we are going to use the constructed W12 to reduce the combined sewer overflow in this storm season,” said Zou.
Until the control facility is complete, Zou says the city will set the gate in a fixed position and raise the water level to divert the flow to the W12 tunnel. He estimates this will happen by the end of June.
The West Edmonton W12 Sanitary Sewer Tunnel won the project of the year 2013 award from the Project Management Institute Northern Alberta Chapter.
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