A traditional dyke to protect Steveston from flooding would cut along Bayview Street through Steveston Village, disrupting businesses, walkways and historical sites.
So, the City of Richmond has come up with a Plan B in its fight to stop rising sea levels and increased storm surges from inundating the city.
This plan entails building a dyke in the Fraser River that runs from No. 2 Road, encompasses Shady Island and ends at Garry Point Park.
While the estimated price tag is hefty – about $170 million – the cost of building a dyke along Bayview Avenue would be about the same and could potentially ruin the ambiance of the historic fishing village.
“We’re sensitive to the Steveston area because there is a lot of history and culture there (that) we don’t want to tear up,” said Jason Ho, the city’s manager of engineering planning.
But throwing a wrench into Plan B is the fact Steveston is a working harbour with boats going in and out daily.
So, to let ships pass through, there would be a 50-metre wide navigational seagate in the middle of the dyke that would only be closed during high tides.
At about four metres high, Shady Island – otherwise know as Steveston Island - is favourably situated to be integrated into this river dyke and there will be opportunities to do habitat and environmental enhancements, largely at the east end, with the streams and marshy areas encompassed into the plan, Ho explained.
He expects preliminary design work, including adding some public amenities, to be done by mid-2022 – but the timeframe to build it is a couple decades out.
“Based on current science, if we get it done within 20 years, we’re in really good shape and it will put us a little ahead of any projected sea-level rise,” Ho said.
The strength of Richmond dyking and pump station system was tested during the atmospheric river that deluged the city in November with 130 millimetres of rain over three days. The city’s pumps were working at 80 per cent capacity over those days – pumping more than a million gallons of water a minute.
Sea level rise – predicted at a metre by the year 2100 – and stronger storm surges due to climate change prompted city council to move up its timeline of shoring up the dykes by 25 years – the original goal was to complete it in 75 years.
Dyke building science evolving
The City of Richmond has a Dike Master Plan, currently entering Phase 4, and a Flood Protection Management Strategy.
But raising dykes and upgrading the city’s 39 pumping stations are just some of the initiatives the city is pursuing.
Last year, there was a public outcry when 300 trees were removed in conjunction with dyke work on the north arm of the Fraser River near No. 8 Road.
Knowledge about strengthening dykes has evolved over the years, and it used to be thought that trees and their root systems kept dykes more stable. On the contrary, their roots can provide a pathway for water resulting in erosion of the dike. Furthermore, if they fall or lean during a storm, they can fracture or breach the dyke.
While the city acknowledged its communication of the tree removal wasn’t sufficient, they were following the latest science on dyke building.
New science – using microbes to strengthen dykes - and natural solutions, for example, fighting erosion at Sturgeon Bank, are actively being pursued. Other plans include building “superdykes” and raising all of Lulu Island above the floodplain.
A field test of a process called microbially induced desaturation and precipitation (MIDP) on a yet-to-be-determined location on the dyking system will be done in the new year to see if this environmentally friendly and cost-effective technique can protect dykes in the event of an earthquake or other potential breach.
The process involves introducing microbes – living organisms – into soil that make it go through a process of denitrification, pulling out liquid and inorganic carbon, which then cements the soil particles, making it stronger.
(According to a scientific paper, a related process called microbially induced carbonate precipitation can be used to restore concrete, artwork and historical monuments and in industrial wastewater treatment.)
Currently, the equivalent technology is to drive stone columns into the ground to stabilize it – something that is extremely costly, Ho said, possibly doubling the cost of raising dykes.
If successful, this microbe-based application would be a “game changer,” he added, and could be used by private development companies.
Living on a platter with 'superdykes'
“Superdykes” are being built in Richmond where the amount of development going up warrants it.
Instead of a dyke being a “trapezoid” – a hilly raised pile of earth that blocks water from coming into the city, a superdyke just becomes a part of the development with the buildings built at the same height as the top of the dyke.
Think of living on a cake platter instead of in a bowl.
From a developer perspective, Ho added, not only is the superdyke reinforcing the dyke with buildings and landscaping, it doesn’t block the view of residents of the first few floors.
And it improves the strength and stability of the dyke, Ho explained.
Superdykes have been built in the Oval Precinct, on the north dyke near No. 4 and Shell roads, at the south end of No. 2 Road. Furthermore, a superdyke is planned at the marine terminal for the Vancouver Airport Fuel Facility, just west of the tank farm currently under construction.
Storms expected to grow in intensity with climate change
While raising and reinforcing dykes is one way to protect against flooding, work is also being done to protect the city against storm surges, which are expected to grow in intensity with climate change.
These bigger storms threaten the city with more flooding and jeopardize the internationally renowned bird flyway and fish habitat at Sturgeon Banks.
Sturgeon Banks was designated a wildlife management area by the province in 1998. It is a feeding ground for at least 47 bird species and is used by hundreds of thousands of birds that migrate through or winter in the area. Furthermore, all five Pacific salmon species – as well as 27 other fish species - use the area at some point in their life cycle.
Dredging the Fraser River has disrupted the natural flow of sediment onto Sturgeon Banks. Left to its own devices, sediment deposit would eventually cause the Lower Mainland to grow out to Vancouver Island, explained John Irving, the city’s director of engineering and public works.
A few strategies are in place to help bring back the flow of sediment: improving jetties to stop the outward flow of sediment and possibly dumping dredged material closer to the shoreline.
“Growing a healthy Sturgeon Banks provides a huge buffer for us long-term from storm surge and sea-level rise,” Irving said.
Could all of Richmond be raised?
Being situated above flood levels would protect the city from being inundated in extreme weather events.
The lower the land is, the more risk there is for groundwater infiltration, explained Jason Ho, causing water saturation in farmland and possible salt intrusion especially closer to the shoreline.
But the fact is large parts of Richmond are in the floodplain.
Raising Lulu Island over the next 100 years is part of the flood mitigation plan, but it’s not something the city is pursuing “aggressively,” Ho said. Rather, it’s being done piecemeal as opportunities arise.
The City of Richmond declared a climate emergency more than two years ago.
An earthquake or a massive storm like B.C. experienced in November are hard to predict. While the city pursues its plans to protect the city from catastrophic events, climate scientists, meteorologists, engineers and other scientists are watching the changing climate and keeping an eye on the speed of sea-level rise as arctic ice melts and water expands as it gets warmer.
Time will tell whether the pace of flood protection measures in Richmond coupled with human efforts to slow down global warming will keep the water at bay.
