The dikes protecting much of the Fraser Valley, including Abbotsford, have been found to be inadequate to withstand an earthquake.File photo

City wants to know about danger quakes pose to Abbotsford’s dike system

City commissioning report to examine seismically unstable flood protections

The City of Abbotsford wants to know how just susceptible its dikes are to a future earthquake.

A 2015 report for the provincial government declared most of the dikes in the Lower Mainland seismically unstable and could fail or sustain damage in the event of an earthquake. The three dikes in Abbotsford that protect thousands of homes on the Sumas and Matsqui prairies were rated “unacceptable” and “poor.” The report found an earthquake could result in liquefaction of sands – a process that can make once-solid land jiggle like jello or act like quicksand. Liquefaction could affect a dike’s stability and also cause “lateral spreading.”

Many of the dikes have also been found to not be high enough to withstand a flood like that which occurred 1948.

The city is now commissioning a new report that will broaden its knowledge about which parts of the 33 kilometres of diking in Abbotsford is most susceptible to damage in an earthquake.

In a request for proposals posted online, the city says “the proposed work is to provide the geotechnical information required for determining the future seismic upgrades of the dikes and is a first step to address the seismic risk.”

The information will also be used to help the city decide on a long-term plan to deal with erosion issues plaguing the Matsqui dike.

The project will take place over two years, wrapping up in the spring of 2019. Its budget of $200,000 is funded by the National Disaster Mitigation Program.

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