Researchers used ground-penetrating radar to find unmarked graves at a residential school site

How ground penetrating radar works Allan Gunter, a GPR Technician, explains how ground penetrating radar works and why it’s useful for searching suspected burial sites.

toronto — The discovery of 215 First Nations children buried in unmarked graves near a former residential school in Kamloops, B.C., has sent shockwaves through Canada.

Researchers used ground-penetrating radar (GPR) to discover anomalies in the ground that preliminary findings identified as burial sites.

The discovery has led to calls for action from Indigenous leaders, politicians and survivors to use this technology at former sites of other residential schools to uncover any other unmarked graves.

But what is GPR and how does it work?

WHAT IS GPR?

GPR is a technology that has been around for decades with several uses in both archeology and infrastructure maintenance. Basically, it sends radio waves into the ground, which are then bounced back to the machine from different depths, which helps users detect differences in densities, and thus any objects that may be under the ground.

“It’s a lot like a fish finder: it takes energy signals and it sends it through the surface of the earth and rebounds off different densities and comes back up,” Craig Campbell, owner of G3Tech, a non-destructive testing company in Saskatoon, told CTV Saskatoon.

“That gives us virtually an image through the earth of what’s below us.”

It’s also a similar technology to that used in ultrasound machines.

A GPR device, which generally looks like an advanced lawn mower, is capable of determining depth, size and material underground, and allows researchers to make these discoveries before breaking ground on a project.

“In the case of looking for unmarked graves and burial locations, what this piece of equipment is able to show are areas that have been disturbed,” Kisha Supernant, an anthropology professor at the University of Alberta, told The Canadian Press last week.

“When you dig a grave, the soil changes -- the composition changes, the density can change -- and the ground-penetrating radar can actually pick up that change.”

WHERE IS IT USED?

In addition to archeology, GPR has several commercial uses, primarily to assess the structural integrity of infrastructure.

It’s sometimes used to examine a bridge for wear and tear, to test roads for any spots that could be vulnerable to sinkholes, or to uncover people trapped under fallen debris.

Construction workers can also use it determine what pipes or electrical wiring may be underground before digging in an area.

HOW CRUCIAL WILL IT BE AT OTHER RESIDENTIAL SCHOOL SITES?

As it’s believed there could be several other unmarked burial sites at other residential schools across Canada, GPR will be crucial in discovering them.

“(We’re) expecting to find graves, because there’s multiple stories of these sites already taking place where they are and -- non-destructively -- we can go in there and pinpoint them so they can go through ceremonies and put up headstones,” said Campbell.

GPR devices are already being used to scan former residential school sites in Nova Scotia and Manitoba, while officials at Algoma University in Sault Ste. Marie, Ont., are mulling over using GPR to locate any unmarked graves at the institution, which was once a residential school.

Additionally, last week the federal government announced $27 million in funding would be available to assist Indigenous communities in finding unmarked graves and memorializing the victims of residential schools.

Last week, Steve Sxwithul'txw started a GoFundMe to buy their own GPR unit to scan the sites of at least five residential schools on Vancouver Island.

“We can’t just sit around, we’ve done enough of that,” Sxwithul'txw told CTV News Vancouver Island. “It’s been confirmed. There’s bodies all across the country at all of these sites I’m sure and sitting around and not doing anything is the last thing we should be doing.”

With a goal of $25,000, the GoFundMe has raised more than $133,000 as of Monday afternoon and now the organizers plan to use the extra money to provide GPR machines and services to other First Nations across the country.

WHAT OTHER DISCOVERIES HAVE BEEN MADE USING GPR?

In June 2020, researchers at the University of Cambridge and Ghent University were able to map an ancient Roman city, known as Falerii Novi, using a GPR device attached to the back of an all-terrain vehicle.

“The astonishing level of detail which we have achieved at Falerii Novi, and the surprising features that [GPR] has revealed, suggest that this type of survey could transform the way archaeologists investigate urban sites, as total entities,” Martin Millett, an archaeologist at the University of Cambridge, said in a statement at the time.

Using GPR, the researchers were able to uncover “a bath complex, market, temple, a public monument unlike anything seen before, and even the city's sprawling network of water pipes,” according to a news release.

In 2012, researchers used GPR to discover the grave of Richard III, who was the King of England and Lord of Ireland between 1483 and 1485, under a parking lot in Leicester, England.

GPR was also used in the investigation into Toronto serial killer Bruce McArthur, which determined several points of interest in the backyard of a home where McArthur stored landscaping equipment, though excavation of these areas did not return any evidence.

With files from CTV News Ottawa News Bureau Online Producer Rachel Aiello and The Canadian Press

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If you are a former residential school student in distress, or have been affected by the residential school system and need help, you can contact the 24-hour Indian Residential Schools Crisis Line: 1-866-925-4419

Additional mental-health support and resources for Indigenous people are available here.