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'Terrifying': Study spells out potential flood impacts in New West

It could cost more than $150 million to upgrade the city's dikes. Here's a closer look at why it matters.

With climate change bringing a rising risk of flooding on the Fraser River, the City of New Westminster is facing a huge price tag to upgrade its dikes — to the tune of more than $154 million.

But the investment could stave off more costly damage, as a dike breach could cause as much as $350 million in building damage.

Those are among the numbers presented to New Westminster city councillors in an Aug. 28 workshop, as council heard a presentation on an update to the city’s flood resilience plan.

The plan — formerly known as the floodplain management strategy — was originally developed in 2010 and endorsed by council in 2011. Over the past two years, city staff have been updating the plan in response to the evolving impacts of climate change, predicted sea level rises and new seismic design requirements by the province.

The city worked with Northwest Hydraulic Consultants Ltd. to draw up the new plan.

Here are some highlights from that plan:

What areas of the city are at risk of flooding?

In total, some 520 hectares of land in New Westminster — encompassing commercial, industrial, single- and multi-family residential properties — is in the Fraser River floodplain.

A seven-kilometre-long dike protects about 350 hectares of Queensborough, while 170 hectares of floodplain lands on the mainland are mostly unprotected. But the report notes the mainland shoreline elevation is typically higher than Queensborough’s and provides “modest flood protection” from most Fraser River freshets.

Four main neighbourhoods of New Westminster are at risk in the event of Fraser River flooding: Queensborough, downtown, the west industrial area (the area around Kruger and Fraser River Pile & Dredge) and the Braid industrial area.

The neighbourhood most at risk is Queensborough, which makes up two-thirds of the city’s floodplain area.

“These are some of our densest and fastest-growing neighbourhoods,” Coun. Nadine Nakagawa pointed out. “That’s not lost on me that we continue to build housing on floodplains.”

How is climate change affecting flood risk?

Future Fraser River flood levels are affected by both the rise in sea levels and potential increases in the Fraser River snowpack and freshet flows, a city report notes.

The current flood design profile for dikes is based on the record Fraser River flood of 1894, which is classified as a one-in-500-year event.

Future designs will be based on the potential for higher levels than that: about 60 to 90 centimetres higher by 2050, and between 1.1 and 1.5 metres higher by 2100.

Given the uncertainty around climate change, the study recommends that dikes around the city be raised to 2050 design levels, with allowances in design and land acquisition to accommodate a future increase to 2100 levels.

What would it cost to improve the city’s dikes?

The study pegs the total cost of upgrading the city’s dikes at $154 million: $120 million for construction and $34 million for seismic work. 

Here’s how those costs break down by neighbourhood:

  • Queensborough: $84.6 million — $55.9 million construction; $28.7 million seismic
  • Downtown*: $23 million — $20.5 million construction; $2.5 million seismic
  • Braid industrial area: $27.1 million — $25.9 million construction; $1.2 million seismic
  • West industrial area: $18.8 million — $17.7 million construction; $1.1 million seismic

(* The downtown area cost includes a Poplar Landing tie-in dike that would be designed to prevent backwater flooding along the low-lying railway corridor into the downtown.)

Those costs are based primarily on earth dikes to accommodate 2050 flood levels, with provisions for future dike raising. In areas where space constraints don’t allow for earth dikes, the plan calls for sheet pile walls that would meet the 2100 levels.

Coun. Tasha Henderson said the costs are “sobering.”

“It really makes me double down on the need to be very careful and intentional about how we’re spending pots of money like the climate action reserve fund,” she said. “We really need to be thoughtful, given the amount of funding that may — or likely will — be required down the road.”

What kind of damage could a flood cause in New Westminster?

A present-day one-in-500-year flood event that breaches the dikes has the potential to cause about $350 million in building damage — $300 million of that in Queensborough and $50 million on the mainland. Most of the mainland damage (about $40 million) would occur in the west industrial lands. 

Not much building damage would be expected in downtown New West because most commercial and multi-family buildings are built to a high flood construction level. But the city notes other damages — including transportation, critical infrastructure and indirect damages — that aren’t included in those figures would be “significantly higher” in the downtown area.

Those numbers stand to increase in future: at 2050 levels, a dike breach would cause an estimated $400 million in building damage in Queensborough, and $100 million on the mainland.

Nakagawa described the numbers in the report as "kind of terrifying."

"We'll be having nightmares about that," she said.

What’s the benefit of upgrading dikes in New West?

The study includes a cost-benefit analysis summary that outlines the potential reduction in costs relative to investment for varying levels of flood protection. On the whole, the cost-benefit analysis shows a much higher return on investment for Queensborough, with the best cost-benefit ratio coming if the city builds in anticipation of a one-in-500-year flood.

On the mainland, the best return on investment comes from building to a one-in-100-year event, but that return on investment is significantly lower than Queensborough’s.

“Based on the analysis, Queensborough should be prioritized for capital spending on flood protection,” the study says.

How long will it take to implement the flood resilience plan?

A city report calls for five phases of work, with the first phase being the updated report received by council last week.

  • Phase 2, planned for 2023-24, would be additional studies and preliminary design work to further understand the cost of diking, the economic risk to the city and the financial risk of implementing diking projects. It also calls for continued work with the province in the development of a B.C. flood strategy to address the question of funding.
  • Phase 3, in 2025, would involve reporting back to council and authorizing staff to develop a long-term funding strategy for the necessary work.
  • Phase 4, in 2025-26, would mean reporting back to council on a long-term funding strategy and implementation plan for diking infrastructure upgrades.
  • Phase 5, for 2027 onwards, would be the full implementation of the flood resilience plan, including further public and First Nations consultation in the design stages.

Is the flood plan ‘aggressive’ enough? Council raises questions

City councillors questioned whether the timeline is aggressive enough, given the uncertainty around climate change.

“This is a huge bill. This is a huge piece of work. I would support us trying to get this going, even accelerate the timeline,” Nakagawa said. “I am just very worried that this will come at us faster than we feel like we need it.”

Mayor Patrick Johnstone said he doesn’t want to characterize the study as “bad news,” but rather as infrastructure planning. But he, too, agreed the timeline raised questions.

“I hear very clearly, and I share the concerns, about timelines, about whether we’re actually being aggressive enough on recognizing that climate change might be happening faster than we modelled,” he said.

He cautioned that flood protection isn’t something New Westminster can do alone; it relies on modelling work done by the province, and it also requires other communities along the river to do their part.

“It doesn’t help us at all if we build to a dike level that Richmond’s not building to,” he noted. “But I do hear that we have work to do.”

Council decision: Plan moves forward

City councillors voted to adopt three recommendations from staff:

  • to adopt the 2050 climate change Fraser River flood profile levels in implementing its future dike projects;
  • to authorize staff to implement the recommendations of the New Westminster flood resilience plan in Phase 2; and
  • to authorize staff to continue to work with the province in the development of the B.C. Flood Strategy to address “critical and sustainable funding” for diking upgrades in the region.

Want to know more? You can find a city staff report on the issue, as well as the full 80-page report from Northwest Hydraulic Consultants, at the City of New Westminster website.