Here's a look inside the facility that leaked 24 billion litres of runoff and sewage

Here's a look at the combined sewage overflow tank that leaked around 24 billion litres of storm runoff and sewage into Chedoke Creek over more than four years.

The bypass gate that was left open is located under a metal plate, down a dark tunnel

This deep, dark tunnel leads to an alcove housing the bypass gate that was left open, allowing untreated runoff and sewage to leak into Chedoke Creek. (Christine Rankin)

The bypass gate that was left open and allowed 24 billion litres of storm runoff and sewage into Chedoke Creek is tucked away under a massive metal plate that leads to a deep, dark tunnel. 

And even when the plate is lifted, you can't really see it. You can peer over the bars that surround the hole, but only partially glimpse an alcove that leads to the gate. 

The tunnel is located in a facility housing Hamilton's largest combined sewage overflow tank.

This is where the untreated waste and stormwater was being stored as it leaked into the creek for over more than four years. And we took a look inside. 

The facility is nestled between Main Street and King Street in Hamilton on a swatch of grass called Cathedral Park. The whole site is four storeys deep and the tank is two-and-a-half storeys deep. The tank can store 75,000,000 litres of storm water runoff and sewage. 

From January 2014 to July 2018, a bypass gate in the facility was left five per cent open, allowing untreated wastewater to flow into the creek. The gate is normally meant to be completely closed. 

Check out Hamilton's largest CSO tank

2 years ago
Here's a look at the combined sewage overflow tank that leaked around 24 billion litres of runoff and sewage into Chedoke Creek over more than four years. 1:06

Machinery opens and closes the gate — normally, silver pistons can be seen rising up plastic tubes when the gate is open. 

Andrew Grice, director of water with the city, explained that since the gate was only open five per cent, the pistons didn't quite make it to where they could be seen. 

The machine is now chained up with a label saying "danger." Grice said that the gate isn't opened at all now. 

This machine operates the bypass gate that was left open around 5 per cent. It's now been locked up. (Christine Rankin)

These systems aren't operated by hand — the machinery is far too heavy for that. Instead, the multiple gates at the facility open and close electronically and can be operated from off site. A control centre above ground turns the power to the pumps and gate machinery on and off.  

Three pumps transfer untreated sewage and storm water runoff between the "wet well" and the Woodward treatment facility. During rain events, the waste is stored — but when the bypass gate was left open, the stored waste flowed out and into the creek. (Christine Rankin)

The public works department also noted that another gate was left open and "likely amplified the spill."

Grice explained that the machine that opens and closes this other gate showed a correct number of rotations, which should have meant the gate was closed. 

But since the gate had become detached from part of the machine, the rotations were happening — but the gate wasn't moving. 

Paper and plastics coat the steps leading down to the "wet well" — the area that collects storm water run off, sewage from people's homes, and waste from the streets. (Christine Rankin)

Waste travels through sewage pipes to the facility with a little help from gravity.

It accumulates in the facility's "wet well," especially during stormy weather. The tank is meant to store sewage and rainwater during storms so that all the extra volume can be sent for treatment later on. If the tank (and others like it in the city) didn't exist, stormwater runoff and sewage would regularly bypass treatment at the city's sewage plant because it is not able to handle the volume.

In this tank three pumps work to move the waste from this well to the Woodward treatment facility. During large rain events, the waste is transferred in and out of the larger storage tank. The tank is made up of two cells — when the first starts to fill, waste flows into the second, larger tank through gaps in the wall.

There are two cells in the storage tank that hold waste. The dark line on the wall shows how high the waste can get in the first tank before flowing through a gap to the second. (Christine Rankin)

If these cells overflow, perhaps due to a massive storm, the waste heads to an overflow trough, which flows into the Chedoke Creek area. Grice said that it would take around 6 hours of a continuous storm to fill the tank. 

When the waste leaves behind a mess of plastics, a massive tipping bucket system flushes out the cells by sending waves of water down the stairs. 

A motion going before council Wednesday night looks at hiring five people to physically inspect the wastewater system.  


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