How does latest leak stack up against the biggest sewage spill in Winnipeg history?

A mechanical failure that sent hundreds of millions of litres of untreated sewage spilling into the Red River ignited outrage over the environmental damage and launchedinquiries into the City of Winnipeg's wastewater system.

You may think that descriptionrefers to this month's sewage spill, which stemmed from a break in a 90-centimetre pipe running under river near the Fort Garry Bridge.

But the scale of this latest leak doesn't come close to matching the volume of sewage that spilled out of the North End sewage treatment plant in September 2002 an event that led to investigations by both the federal and provincial governments and toconsequences Winnipeggerscontinue to pay for.

On Sept. 16, 2002, a part of a valve inside one of the plant's six pumps got lodged open.

"A staff team concluded incorrectly that the valve was closed but not 'seated,'" a December 2002 report from the city's water and waste department states.

WATCH | Here's how the latest spill compares to the one in 2002:

How does the latest sewage leak stack up against the biggest spill in Winnipeg history?

7 months ago

Duration 2:20

This isn't the first time a sewage spill has dumped hundreds of millions of litres of untreated sewage into the Red River.

When staff loosened a 30-centimetre-diameter inspection plate, it blew off the pump, and interconnecting tunnels between the plant's three pump wells allowed them all to flood, submerging the motors and shutting down the facility.

Unable to pump through the regular wastewater treatment process, the city's combined sewer outfalls dumped 427 million litres of raw sewage into the Red River before the plant was back in service just after midnight on Sept. 19, 2002.

That's almost double the volume of the latest Winnipeg sewage spill, which began on Feb. 7and released nearly 230 million litres of sewage into the river before the leak was stopped this week.

The Manitoba government says it is investigating the latest leak.

After the 2002 spill, the federal government charged the city under the Fisheries Act for dumping "a deleterious substance into a fish-bearing waterway."

The city could have faced a fine of $300,000 at the time.

A trial began on June 6, 2005, and was expected to last several weeks. On June 15, however, the federal prosecutor in the case announced there was insufficient evidence to prove criminal neglect.

But that didn't mean the City of Winnipeg was off the hook.

North End plant upgrades

In 2003, the Manitoba Clean Environment Commission,an arm's-length provincial government agency,ordered the city to make major upgrades to the North End plant to removenitrogen and phosphorus two nutrients linked to toxic blue-green algae blooms on Lake Winnipeg from wastewater.

That's one of the city'sobligations under its Environment Act licence.

Conducted in three stages, the upgradeto the sewage treatment plant the city'slargest and oldest, built in 1937 and responsible for treating 70 per cent of Winnipeg's wastewater is one of the most expensive and complicated projects in Winnipeg's history.

Originally expected to wrap up in the early 2010s, the upgrades are now expected to take until sometime in the 2030s, at an estimated cost of $2.2 billion.

Work on the first stage of the projectthe power supply and headworks,where untreated sewage and stormwater enters the plant is nearing completion. City council recently approved a $44.5-million increase to the budget for the headworks project, to a total of $518 million.

Council also approved a $482-million increase to the second stage of the project, the biosolids facilities, now estimated to cost just over $1billion.

The third and final stage of the project will build nutrient removal facilities to take nitrogen and phosphorus out of the water before releasing it back into the river.

It isn't the only massive project the city is undertaking to reduce the amount of untreated waste it spills into the waterways.

The city is also working to replace its combined sewers, common in older neighbourhoods, which carry both street runoff and wastewater from households and businesses.

About one-third of the city still has combined sewers. During periods of heavy precipitation, the flow can exceed the capacity of the combined sewers, dumping diluted sewage into the river.

That project is expected to cost between $1.5 billion and $2.3 billion.

Council has set a target to complete that project by 2045.