Abbotsford’s dikes are in fine shape, aside from the one with an eight-foot-deep sinkhole in the middle of it and another being constantly eaten away by an unstoppable river.
A recent inspection of the city’s dikes declared them to be in “excellent shape” generally, although there are a few items in need of prompt repair.
The problem of most immediate concern is a sinkhole eight feet deep and eight feet wide, that has has developed in a dike near the wastewater treatment plant that serves Abbotsford and Mission along the Fraser River.
The sinkhole has been backfilled as a temporary measure and is being inspected daily while plans are made to fix the situation, according to reports to a pair of city committees. The hole is located just east of the JAMES wastewater treatment plant, and is immediately above an outlet that allows water to move between Matsqui Prairie and the Fraser River.
A ground-penetrating radar survey has already been undertaken, and analysis of the results is now being done. There was also a CCTV inspection of pipes. A staff report predicts the repair will be completed by the end of February, before waters start to rise in the spring.
The cost isn’t yet known, and the report says “contingency funding may be required.”
It’s unclear if the hole could be linked to larger structural issues with the Matsqui dike, which – like most others that line the Fraser River – have been found to be seismically unstable.
A 2015 assessment of the Matsqui Dike deemed its seismic stability to be “unacceptable,” noting that it would be susceptible to “possible liquefaction of sands” in the case of an earthquake. That could affect the stability of the dike. It’s general stability, though, was labeled as “fair.”
In January, the city commissioned a report on the susceptibility of its dikes to a future earthquake.
Several reports have repeatedly warned about the dangers posed by a major flood that could swamp the Fraser Valley’s dike system – which studies show is insufficient to prevent a disaster if waters rise as high as they did in 1894. But no one has yet come up with the billions of dollars necessary to improve the dikes. In Abbotsford alone, upgrading dikes to meet provincial standards is expected to cost around $420 million.
The city doesn’t want to pay a penny of that cost, with a new masterplan stating that the provincial and federal governments should pick up the tab.
The diking assessment also found that a previously small erosion arc along the Fraser River has apparently expanded significantly. The arc is located next to others along the Fraser River and immediately adjacent to an arc that had just recently been repaired to the tune of more than $1 million in provincial emergency funding.
The city has previously also spent more than $1 million of its own money on such “band-aid” solutions to halt the Fraser from eating away land that sits between the dike guarding Matsqui Prairie and the river itself.
In 2016 and 2017, the province gave the city $14 million to improve its flood defences. The city had developed an $8-million plan to build underwater rock spurs to redirect the flow of the river away from those spots now seeing erosion. But little has been heard of the project since.