We now know what caused a foul smell near Science World Thursday night.
According to the city, the stench was the result of seawater mixing with sewage that emerged from the site of a broken sewer main.
Officials say repairs are underway but will likely take another three weeks.
Vancouver’s general manager of engineering, Lon LaClaire, says the minor leak is no cause for concern. He tells CityNews repair work on the main on Terminal Avenue is complex, adding it’s different than much of Vancouver’s sewer infrastructure.
“This location is very unique because it’s in a low lying area, and so unlike much of our sewer system, this section is subjected to tidal influences. The water table in this area is actually affected by high tides. And so that spill occurred during the high tide moment,” said LaClaire.
LaClaire says the city won’t know the extent of the fracture until it’s fully exposed, but crews are on site “24/7” monitoring to make sure nothing more “unexpected comes up.”
In June, effluent pooled on the street in Vancouver’s Olympic Village neighbourhood, and more spilled into False Creek after a sewer main broke.
LaClaire says he can’t directly address the June spill, as it came from a sewer under the District of Metro Vancouver’s commission, but suspects that the two incidents are related.
“[The Olympic Village] location, similar to ours, has a lot in common in the influences of the tide. And the fact that seawater can make its way into the groundwater and ultimately inside the sewer system itself, which is really a lot more corrosive than our typical sewage. So it’s possible that what’s going on with both of these locations is similar,” said LaClaire.
LaClaire says, surprisingly, both broken mains were only around 25-years-old.
“Typically, with these pipes, we would expect them to not fail — that they would last for about 100 years. So a failure of this nature is surprising.”
LaClaire says the problem is unlikely to be widespread, given that the two recently broken pipes are so unique. He says both pipes are made from similar materials, they sit in similar “porous” ground conditions, and their low, almost sea-level position means they are both “force mains” — sewers powered by pressure systems, as opposed to the 2,100 kilometres of gravity-powered pipes in the network.
That combination of factors, LaClaire suspects, is the cause of the failures, adding that he won’t know the reason until the conclusion of the city’s inspection.
“At this point, we don’t have any concerns. In fact, this does feel like, really, a rare event. In fact, water main breaks are very common, so we might have 100 of those a year. But this is only the third sewer main break that we’ve had in 10 years. So this is, it’s not a common thing at all.”
LaClaire says because force mains are typically buried closer to the surface, repairs outside Science World should be “relatively easy.”
He says the city is working towards a sustainable sewer replacement rate, which would involve upgrading around one per cent of the system every year.
—With files from Cole Schisler.