Own a home in Vanier? You might be living on a former dump.

That's according to a 14-year-old report commissioned by the City of Ottawa that was recently analyzed by Radio-Canada.

Produced by Golder Associates, the 237-page document contains maps and detailed descriptions of 82 former landfill sites in the city.

And while most of those were turned into parks, some now sit beneath residential neighbourhoods — and virtually all of those sites are in Vanier.

In fact, according to Radio-Canada's analysis, almost a quarter of the inhabited area of ​​Vanier was once either a garbage dump or site contaminated by industrial waste.

This map shows the location of some of the former dump sites east of the Rideau River. The white outline marks the Vanier border. (Radio-Canada)

Heavy metals

That's partially due to the fact the firm which built the interprovincial Alexandra Bridge, the Dominion Bridge Company of Canada, once owned a manufacturing plant on Landry Avenue and operated a smelter next door.

The company, which ceased operations in 1969, was once one of Vanier's largest employers. The City of Ottawa says it believes any potentially-contaminated soil from the site was hauled away.

Still, five decades after Dominion Bridge company closed down, there are still traces of heavy metals close to the surface of the nearby garbage dumps upon which post-war houses were built.

The city considers it enough of an issue to publish yearly notices informing residents of the hazards of those metals. Lead, for instance, can affect cognitive abilities, especially in young children. Some metals like arsenic can be carcinogenic, while mercury can be harmful to the nervous system.

In addition to those seven sites, Vanier also had two other large landfills: one in the former Domaine des Pères Blancs, and the other between the Beechwood Military Cemetery and Notre-Dame Cemetery.

That said, the city also told Radio-Canada it actively manages and monitor its former landfills, working with Ottawa Public Health when a potential public health problem arises.

It also said it complies with all provincial rules and standards for the management of these former sites.

The building of the Alexandra Bridge is one of the main reasons Vanier is laden with former industrial sites and landfills. (Trevor Pritchard/CBC)

Gas concerns

Former dumps like the ones beneath Vanier can also be sources of methane gas, which is formed when organic matter decomposes.

Methane gas is potentially explosive and can infiltrate into homes through cracks in their foundations. Studies conducted for the City of Ottawa in 2007 and 2017, however, concluded that the presence of methane in the soil of the two former landfills posed no threat to residents' health.

Am I built on an old dump that once existed there? It's all very likely. But I don't know. - Marc Pitre, Vanier resident

But when that organic matter decomposes, it also leaves behind empty space — and when the soil settles, it can damage homes, said Chris Kinsley, an environmental engineer and a professor at the University of Ottawa.

That's what Marc Pitre, who's lived for 30 years near the former Domaine des Pères Blancs dump, says he's been noticing.

Pitre says experts told him a few years ago that his house was probably built on muddy ground that was going to shift frequently. Now, cracks and crevices have been forming in his foundation — and other nearby residents told Radio-Canada they were going through the same thing.

"I was born in Vanier. We've always known the Vanier neighbourhood had several dumps," Pitre said in French.

"Am I built on an old dump that once existed there? It's all very likely. But I don't know."

Interactive mapping

The report that formed the basis of Radio-Canada's analysis was submitted to the city's planning committee in 2004.

The City of Ottawa said it feels the report is sufficiently accessible to members of the public, as it's available at municipal libraries and customer service centres.

It was also added to the open data catalog, weeks after Radio-Canada began requesting information about the sites.

Following a similar investigation by Radio-Canada, the City of Montreal created an interactive map that allows Montreal residents to find out if homes are located on former dump sites.

The City of Ottawa has told Radio-Canada they're now in the process of updating their own interactive map to include the geographical location of the old landfills, in the hopes that the data will be more accessible to homeowners, homebuyers and real estate brokers.

With files from Stéphane Leclerc