Richmond faces $300-million tab to upgrade dikes 0
Parts of Steveston's waterfront, including the historic Gulf of Georgia Cannery, are currently unprotected by the city's existing dike infrastructure should waters rise. The new dike would include the building within its protection. (CARMINE MARINELLI/ 24 HOURS)
As Richmond works to shore up its defences due to the looming threat of rising sea waters, a city update estimates it would cost up to $300 million to upgrade a conventional dike system that surrounds the island community.
To date, the city has determined its best option for the historic Steveston community — in the southwest corner of Richmond — would be a new dike that extends to the sea, surrounding the village’s harbour with a rock wall and a floodgate that would be shut as storm waters approach.
According to a city report, staff expect that option to cost $55 million and it’s likely the upgrades wouldn’t be complete for years, if not decades. The city is also seeking funding from provincial and federal governments.
Richmond’s plan is to build its dikes 4.7-metres tall, more than a metre above provincial standards, to fight sea-level rise over the next century.
Andy Bell, a Richmond project engineer, said Wednesday the Steveston plan would eventually sacrifice Garry Point Park to the sea — turning the area into a high-tide flood zone — as a new dike would be constructed further inland to protect the built-up areas of the village.
Currently, Richmond’s dike system, created in the 1970s, does not protect some areas along Steveston’s waterfront and there isn’t sufficient room to build a dike along the immediate shoreline.
Along the city’s western front, according to the report, a mudflat area called Sturgeon Banks that serves to break up waves is eroding — potentially allowing the swells to build up again. One option could be to build a “barrier” in the sea for waves to crash into before they hit Richmond.
The community currently spends about $10 million each year to upgrade dikes and drainages. The city has 41 pumping stations, monitored constantly, that work to clear water from its 600 kilometres of box culverts and storm sewers, and about half that length in drainage ditches.
A potential earthquake is also a problem. Richmond has received grant funding it’s using to consult with a firm for an emergency operations centre to connect decision-makers in case of a disaster.
There are also strategies to build dikes that would resist quakes, according to the report, which explains the city could shake the dike to “compact” the soil, making it tougher. Other options include injecting additives into the soil to prevent liquefaction, using stone columns to strengthen dikes or to build the barriers larger than necessary to increase stability.
The city has a number of ongoing initiatives:
- Dikes are maintained and inspected weekly
- Brush and trees are regularly removed from dike areas to preserve the barriers’ structural integrity
- Annual survey to ensure dike elevations are maintained
- Constant river monitoring at four locations
- A policy to outline initiatives for flood protection
- Seismic study to determine impacts to dikes and where to strengthen them