Pitt Meadows flooding in 2005. (THE NEWS/files)

Pitt Meadows flooding in 2005. (THE NEWS/files)

Pitt Meadows needs $121 million for dike upgrades

Dike system would fail in most extreme flooding and seismic events

It is going to cost an estimated $121 million to get Pitt Meadows’ dikes high enough and wide enough to protect the city against flooding.

Senior government will have to get involved, said Mayor Bill Dingwall.

“We could never tax our way out of this. We would bankrupt the city,” he said.

Council heard a presentation from staff about the city’s recently completed Flood Mitigation Plan for the city. It builds on work begun with a 2018 risk assessment, which found potential flood-related economic losses would be $489-$725 million in Pitt Meadows.

READ ALSO: Pitt Meadows gets some help for flood plan

“The risk of flooding is generally low, but the amount of economic loss should there be a flood, or failure in our dike structure… it would have significant impact,” explained director of engineering Samantha Maki.

Maki presented council with maps showing the flooding that would result from a historic one-in-500-years flooding event brought about by high spring melt and heavy rainfall. It showed most of the city under water, save for an “island” in the downtown core. That higher area would still be cut off from the major road network by water, noted Maki.

“Eighty-six per cent of our city is in the flood plain, so we cannot minimize the significance of this,” said Coun. Nicole MacDonald. “I have heard quite a bit of concern from our agricultural community as well. Obviously that’s their homes, their livelihood, their farms.”

She asked that council’s plans be shared plans with the agricultural community.

A second map showed the results of that same one-in-500-years event, compounded by the effects of climate change and ocean rise. It predicted deeper flooding, with most of the city north of the Lougheed Highway under water that would be deeper than four meters.

In April 2018, ISL Engineering did a flood hazard risk assessment for the city. It found the majority of the dikes are insufficient for severe flooding or seismic events. All dikes are about one meter too low, and need to be upgraded in both height and width. Dikes will need to be wider in some locations, and half of the areas examined are considered high priority for seismic upgrade. There are 60 km of dikes.

“Virtually all of our dikes were built in the 1930s and 1940s, and aren’t up to modern standards,” said Dingwall.

READ ALSO: Pitt Meadows needs help with flood protection

Nearly all dikes will overtop or fail in the most extreme flood events. About half of the dike length protecting the most populated area is at seismic risk.

The first priority for the city should be a stretch of dike that runs along the Fraser River from Fraser Dyke Road/176th Street to the city’s eastern border. It would tie in to a potentially new dike structure on Katzie First Nation’s Reserve No.1.

Dingwall noted both Surrey and Chilliwack have received significant dollars from the federal government for flood protection, and he asked staff to write senior government and “start the advocacy role now.”

Unique in that so much of the city is in the flood plain.

Done the homework, made the case, now need the finances.

The city also needs to replace two pumps, in the drainage system, but that is already in the works for 2021 and 2022.


 


ncorbett@mapleridgenews.com

Like us on Facebook and follow us on Twitter