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Overview of Iona Island treatment plant (Image courtesy of Metro Vancouver)

Climate change to trigger a flood of sewerage costs

On a stormy day, angry surf crashes against the Iona Island jetty with enough force to shake its foundations. The…

By Adam Pez , in Environment , on March 30, 2012 Tags: , , , , , ,

Iona Island wastewater treatment plant
Overview of Iona Island treatment plant (Image courtesy of Metro Vancouver)

On a stormy day, angry surf crashes against the Iona Island jetty with enough force to shake its foundations. The jetty is a 4-kilometre needle of land that sticks out into the Strait of Georgia, exposure that ensures it’s in need of constant repair.

It costs the Greater Vancouver Regional District (GVRD) up to $2.5 million annually to keep the jetty from washing away, but it’s money well spent. The jetty’s rocks protect a 7.5-kilometre-long deep sea pipe that disposes approximately 500 million litres of treated sewage from the Iona Island Wastewater Treatment Plant each day.

But the plant, and the pipe attached to it, are two pieces of Metro Vancouver infrastructure most vulnerable to climate change. And the money spent by the GVRD to shore up the Iona Island jetty represents a small foretaste of the hundreds of millions of dollars that will be needed to protect the city’s sewer system in coming years.

Iona plant at risk

The Iona Island plant, built in 1963, treats the waste of more than 600,000 Metro Vancouver residents, representing a major piece of infrastructure. But like many wastewater treatment plants in coastal cities, it was built near the water, where gravity, and proximity to the plant’s disposal point — the ocean — would help save money.

Iona’s location at the mouth of the Fraser River puts it “front and centre” of Metro Vancouver’s efforts to deal with increased storms and rising sea levels, said John Clague, a Simon Fraser University (SFU) geoscientist and research chair of SFU’s Centre for Natural Hazards Research.

Now, however, the plant’s convenient location is proving its Achilles’ heel, for with climate change comes rising oceans, increased rainfall and more intense storms which, when combined, risk flooding the plant.

“It’s not the gradual rise in sea level; it’s the severe storm that works on the ocean when it’s at a higher level that raises the likelihood that waters will over-top the dyke,” said Clague. “They’re not designed for water levels that are 70 centimetres higher than they are today.”

Clague also spoke on sea level rise for the North-Eastern Pacific ocean during the annual American Association for the Advancement of Science conference, hosted in Vancouver this February. He provided revised statistics on sea level rise that showed past projections, such as those provided by the Intergovernmental Panel on Climate Change (IPCC), had been conservative.

The West Coast should expect an average sea level rise of 70 cm to over a metre by the end of the century, said Clague. For Iona, however, that rise in sea level is paired with subsidence of the land it rests on.  Iona Island, like much of the Fraser River delta, is slowly sinking at a rate of one to two millimetres each year.

“That plant isn’t designed to sit in standing water,” said Clague.

The confluence of sea level rise and sinking land are what make Iona so vulnerable.  A 2008 report for the GVRD said the two forces left “very little margin… available in the future” for the Iona Island plant. The 2008 report’s projections were based on an average sea-level rise of 50 cm.

Brent Burton, a senior engineer for the GVRD, said the plant faces a host of problems brought by climate change. The jetty is at risk of being eroded by higher, stormier seas, and the island’s dykes will need to be raised, too.

Rising water tables pose another risk by putting more pressure on building foundations, said Burton, and an increase in rainstorms could overwhelm the plant. Indeed, in December 2009, heavy rains and severe weather caused Iona to lose power and discharge 116 million litres of under-treated sewage into the ocean.

Paying for new sewerage

The spectre of climate change comes as the Iona plant’s operators and owners, the GVRD, intend to replace the old plant in order to fix its dirty reputation.

The GVRD plans to spend $1 billion to build a new secondary treatment plant at Iona by 2030 and possibly as early as 2022-24, said Burton.

He said a small portion of the total sum will be needed to shore up Iona from climate change. The money will be used to ensure the plant lasts until 2100, when it is scheduled to be retired.

But a far pricier problem for municipal wallets will come from fixing sewers. Currently, Vancouver’s combined sewer system channels excess storm water from city streets into the Iona plant. The City of Vancouver has pledged to segregate its sewers by 2050 in part to reduce the stress on Iona.

A 2012 administrative report by the city found the tab for replacing aging pipes will be expensive. Current sewerage costs of roughly $45 million a year are estimated to increase beyond $160 million annually by 2030, which will translate into raised sewerage rates for Vancouver homeowners.

The price of climate change

Sewerage, nonetheless, represents just a fraction of a far greater problem.

A 2009 study conducted by the United Kingdom-based Tyndall Centre for Climate Change Research concluded that a sea level rise of 0.5 metres by 2050 would put $28 trillion (U.S.) worth of assets in 136 major coastal cities under threat. If that’s the case, Metro Vancouver ports and the Tsawassen ferry terminal would have to be reinforced against rising seas. And according to Clague, Richmond and Delta would need to raise their dykes, which would cost some $200 million.

Sewerage, out of sight beneath city streets, is where the costs of climate change will be felt first, and the cost of maintaining sewerage will only grow in coming years.

The sooner municipalities can act, “the less [they’re] going to have to take out of the bank later on,” said David Flanders. He works on Collaborative for Advanced Landscape Planning (CALP), a University of British Columbia (UBC) project that provides B.C. communities with 3D visualizations for climate change adaptation strategies.

“The place to start would be locally and very, very small,” he said.

Protecting Iona

There are a number of ways that the pressure on the Iona plant and Vancouver sewage system could be relieved that would be cost effective and have additional environmental benefits.

Some solutions are simple. For example, a 2008 Metro Vancouver report found that the impact of increased heavy rainfalls could be reduced by installing green infrastructure such as porous pavement, rain gardens, green roofs, and rain barrels to capture extra water. That stored water, in turn, could be used to irrigate lawns and gardens during hot summer months.

A far more labour-intensive solution for protecting the plant would involve rejigging how the Metro Vancouver wastewater system works. Part of that solution involves segregating sewers, which the City of Vancouver has pledged to do.

But Christianne Wilhelmson, executive director of the Georgia Strait Alliance, said the GVRD’s plans to replace the old Iona plant also provide an opportunity to innovate on how we deal with wastewater.

Iona and the Lions Gate wastewater treatment plants — which only offer primary treatment of sewage — have been in the crosshairs of environmental groups for a decade. Wilhelmson said she was involved in litigation against the two plants for failing monthly toxicity tests mandated by the federal Fisheries Act.

The new Iona plant can’t “be like we built it 40 years ago,” she said.

She recommended a system of smaller, distributed wastewater treatment plants — rather than a single, centralized one — as a way to assist or replace Iona.

A 2008 Capital Region District (CRD) report on Victoria sewerage recommended a distributed system of smaller plants as an alternative to installing a large secondary treatment plant. The report found smaller plants could cut CRD infrastructure greenhouse gas emissions by a quarter and help save $6 million in annual energy costs.

As an added benefit, smaller plants could be located in neighbourhoods away from rising seas, said Wilhelmson.

“I don’t think people understand how things have changed; they still have a view of wastewater treatment plants as being stinky and horrible,” she said.

Burton said the GVRD is currently drafting a report, due out in 2014, that will name specifics on the budget and strategies for protecting the Iona plant from the effects of climate change. Installing distributed plants is one item being considered, he said.

In other words, the threat climate change poses to sewerage, and the coming environmental and fiscal costs, has opened a space for a quiet meeting of minds between environmentalists and city engineers.

View Metro Vancouver wastewater treatment plants in a larger map